Exterior Drum Practice room build plan, Wales, UK

Hi I have a final draft of my studio build plan - I hope you guys dont mind that I've attached it as a document rather than writing in the message body - I tried to paste it in to here bit I lost all of the images and links. Here it is: Anyway, would very much appreciate any views from the experts. There are a couple of questions in red that I have included. Kind regards James

I hope you guys dont mind that I've attached it as a document rather than writing in the message body

Actually, I think you'll find that people do mind. That's one of the forum rules, actually: to post everything directly in your thread wherever possible, for a very good reason: to make it simple and easy for others to scroll through your entire thread in the future and see it all at a glance, without having to download text and photos from separate files. The idea is that it all makes sense and is easily visible and fully documented, in a logical sequence, with replies falling in the chronologically correct places in your thread. That's not to make it easy for you, but rather to make it easy for others who might want to follow your thread now, or in the future after your studio is fully completed and you have long-since moved on from the forum to other things... For example, right now if I reply to the second paragraph of page 2 in your PDF, by saying "You do realize that by doing it that way, you wont get the same results?", then that is basically meaningless to anyone else since there is no context. Even if I quoted the paragraph itself, it would still be meaningless without the rest of the context, and the accompanying image. And nobody is going to bother doing what I bet you just did: Opening your PDF document to page 2, to see what the hell I'm talking about! :) In short, by not posting the text and photos directly to your thread, you are saying: "I'm too lazy to make it easy for other people to follow my build, since I can't be bothered to post my text, photos and links on the forum like everyone else does, so you'll all have to do that work yourselves if you want to help me, by looking everything up in my PDF documents each time before you reply!".... I think you can imagine how well that will go down, and how many people will be willing to help you! :) I took the time to read through your document, and there are many things that I wanted to comment on, point out, suggest how you can fix the mistakes, or suggest ways you could things better/more safely/more cheaply. But I'm not going to take the extra time that I'd need to cut and paste each paragraph from your PDF to the forum, along with the photos, links and diagrams, nor am I going to quote page and paragraph number then add a comment afterwards that would be cryptic and meaningless to others. So I'd suggest that you post the text, photos and links here on the forum, exactly as you have them in the PDF. Yes, it might take several posts to do it, and yes it will take time to upload each image individually, and to add the off-site links in the right places. You might even need to go back and edit your posts several times until you get it all right.... But if you can't be bothered to do that to make it easy for the folks who are here to help you (for free!), then why should they be bothered to help you at all? - Stuart -

Sincerest apologies - I should have re-read the rules before posting. Please ignore this thread and I'll reconstruct it again later :oops:

Ok - take two. Apologies again for my previous post. Here is my plan - comments appreciated! The studio will be sited in the corner of a residential garden in a quiet rural village. Closest neighbour is approximately 70m from the studio. It will be used for drum practice and tuition, so a good level of sound reduction is required (STC of at least 60). Image 1: The building will be 1m from the fence and stone wall: I had a mound of what I thought was earth here; it turned out to be massive stones from a local castle! Image 2: The site as of today – with boards indicating approximate position of the build Image 3: birds eye view of the concrete pad footprint A 4.8m x 5.4m concrete slab is being laid to a depth of 5 inches. It has 4” of compacted hardcore underneath; and a damp proof membrane below the concrete which will lap over the side of the concrete slab and be secured under the 2x4 frame soleplate. The two additional rectangle areas on the diagram above will be used to site baffle boxes – discussed later. Summary of build plan I am hopefully not cutting corners; but certainly erring on the side of economy as I have a limited budget for this project. So – cheap and reclaimed materials where possible (for example, I picked up my two fire doors for a meagre £5 each). The construction will be a double wall assembly. I will make a final decision next week on whether the outer wall will be constructed of concrete block instead of double thickness chipboard. This is really a cost consideration – I think either approach will give the results I require. However the other benefit of using block will be at least a sense of it being more robust; particularly given that I’m using single beams to construct the ceiling and roof off the two independent room walls. If I use concrete blocks, I will still use the same materials for the roof as below though. For now though, I have specified the more likely timber / chipboard option in this plan. In general I am going to follow the below specification from the NRCC document (page 350). Some changes (ie, chipboard and OSB instead of plasterboard on external frame). Outer frame The framework will be constructed using 4 x 2 untreated timber. • Firstly, a treated 4x2 timber soleplate will be secured to the slab with the DPM folded over the top and then tacked onto the top of the soleplate. I will secure the soleplate with tapcon type frame anchors – 5 on each side of the frame, spaced evenly. • The outer frame will have uprights at 400mm centres, and staggered noggins. I will be using decking screws, not nails for all framing. • The frame will have a double top plate, which will intersect with the frames for the other walls to tie the structure together. • On the front facing wall there will be a door and window, which will have additional uprights and noggins in the frame to create / support the opening. • The outer frame height will be 240cm at one side; and 220cm at the opposite side (to create a very small roof gradient). There is an embarrassingly bad unfinished illustration below which may convey the idea here. The uprights and noggins are missing off the frame… sketchup has defeated me I’m afraid…but I managed to get the horizontal top place and slanting member on the edge matching where the joists run. • There will be noggins at intervals, to match it up to the header of the squared frame. Board will then be applied to cover all of the side all the way up to the roof boards. The roof boards will protrude over the edge of the frame by 10cm. • The outer frame will be covered by with 8x4 chipboard, with 8x4 OSB then going on top. I will paint the OSB with exterior contract paint to give some basic weatherproofing. • To further protect the OSB and to improve weatherproofing, featheredge boards (here) will be applied onto 1x2 uprights spaced roughly 1m apart that I will screw (to a shallow depth) and glue onto the exterior OSB. I don’t want to penetrate the OSB with screws, so just using glue would be preferable if it holds. Any thoughts on this? The roof • The outer frame will have a flat roof, with a gradient of 1:24. As discussed above, the frame on the higher side will be 20cm higher than the one on the lower side. • A raised edge trim will be used on 3 sides of the roof (as diagram below), and the 4th (lowest) edge will have a gutter. All of the roof boards will overlap the edge by 10cm. Image 7: Comparing to this diagram; my approach will look the same apart from the firing strip. I am raising one side of the frame by 20cm instead. I will secure the joists to the wall plates with truss clips (below) Image 8: exterior frame truss clips: • The roof will have 8x2 joists. They will be spanning a wide area (480cm) but from what I’ve read, it will be structurally ok for these to be supported by my 4x2 frame. However, the other option of concrete wall feels more appropriate, hence considering this. • The 8x2 joists will be spaced 40cm apart and will have noggins half way up. • The roof will be boarded with 8x2 chipboard, with 8x2 OSB then going on top. • The same screw pattern will be followed as for the boards on frames; and caulk applied liberally. • An EPDM membrane will be applied to the roof (the thicker grade http://www.rubba-seal.co.uk/order+form). The inner frame • The inner frame will be built of 4x2 timber, with the door and window openings married up with the external frame. There will be a gap of 10cm between the inner and outer frames. This reduces my inner frame area to 480cm x 420cm (that’s before I attach the boards). So – the final room size will be around 470cm x 410cm. • The inner frame will have the same construction approach as the outer one; but studwork will be centered ‘opposite’ to the outer frame. • The inner frame ceiling will also have 8x2 rafters spaced in the same way; but the joist hangers will be the type below, attached directly onto the double top plate of the framing. There will be no gradient on this one. The frame height will be 205cm (to under the double top plate); leaving a 5cm air gap between the lowest point of the outer frame. Cavity insulation • I will insulate each of the independent stud frames using 10cm low density fibreglass insulation. Each of the outer and inner faces (8 sides and 2 ceiling) are between 20 and 28 square metres. I will buy 250 square metres of low density rolls here. Doors • I have 2 x large heavy duty fire doors, sized 1980mm x 864mm. • On the outer frame, the door will open outwards. Once hung correctly, I will attach an additional layer of 12mm chipboard to the door. • I will use 3 x heavy duty hinges for each door. • There will be a full rubber seal around both doors: I will be using the kit here. • The same approach will be applied on the inner frame door, with that door opening inwards to the room. • I have a mortise lock on the outer frame door. Aside from caulking any non-moving parts I haven’t figured out what else to do to minimise flanking through door hardware at the moment. Thoughts appreciated. Window • I have 4 sheets of 6mm laminated glass, sized 1936mm x 676mm. These will be doubled up, and installed parallel / facing each other in the outer and inner frame. I will sit them on a strip of neoprene so the glass isn’t toughing the frame directly all the way around; and to allow caulk underneath the glass. Image 11 ..to illustrate one of the window frames • Each frame will be constructed from 6x2 hardwood, and fitted to give a narrow ledge on the outside and inside boarded walls. The frames will obviously be built to exactly fit the glass within 1-2mm. • The window frames in each wall frame will not touch each other, but I will tidy up the internal gap in between the frames by attaching a black neoprene strip all of the way around to effectively close the gap between the two sections of 6x2. I’ll put a few sachets of silica gel under the strip. • Caulk will be applied liberally prior to the 2x2 securing strips being screwed into place. A silicone sealant will also be applied along the window and 2x2 join post fixing. HVAC • I wont be recording in the room, and on all but a few occasions there will only be me in the room. I have therefore taken the view that a comprehensive HVAC system isn’t a priority. However I want to be able to move air in and out while I am in there / possibly overnight to freshen the room and remove moisture / avoid condensation. Two vents will be placed low down in my room (approx. 20cm upwards of the floor). They will be on opposite-ish sides of the room (as per the footprint diagram at the top of page 1). • I will build 2 x external baffle boxes, sited on the 120 x 35cm concrete pads shown on page 1); the vents sitting inside the frame where these boxes are located. • The baffle boxes will each house a 125mm vent axia Powerflow duct fan http://www.vent-axia.com/range/powerflow-line-duct-fans.html). One will push air in, and the other will push air out. • I couldn’t draw in the snaking duct, but the idea is that the duct snakes between the gaps in the board. All of the cavity is filled with rockwool. The box is constructed of 2 layers of chipboard. The lid (double board thickness) will be sealed on, and painted with bitumen paint; then covered in spare sections of the roof covering material. I’ll be able to take the lid off for maintaining the fan, but will need to reseal each time Image 12: Baffle box design: Size is H – 35cm; L – 120cm; W – 35cm • If I need heating I will use an oil filled radiator in the room. I also have a dehumidifier that I will use frequently to remove excess moisture. • If I find that only having external baffle boxes isn’t insulating well enough, I will construct baffle boxes in the interior of the room too. Or should I plan to do this at this stage anyway? Power supply • 40 Amp, 10mm cable will run to the studio to an external consumer unit which will be sited behind the building above one of the baffle boxes. One cable will run directly into the studio via a flexible pipe that will be inserted into the concrete slab when it is laid. I will then fill the remaining space in the pipe (with sand?) and seal / bury it. • Two additional cables will run directly to the inline fans in the baffle boxes; entering next to the ducts. • On the inside of the studio, cable will be run through self-adhesive cable trunking. Nothing will be attached to the inner side of the room with screws or nails. • Low voltage LED lighting, a computer, keyboard, 100w amplifier and speakers is all that I will be running in there so power demands are on the low domestic side. • I will be asking a local electrician to help me with the internal distribution of power; so haven’t gone into detail here. However as a rough idea I’m thinking of 3 x twin sockets and 8 x low voltage LEDs. • The basic principle is that one power cable will enter the inner room, and will be distributed from there internally using trunking / no screws or nails. Is this a decent plan? Flooring and sound control • The room will be carpeted with underlay followed by a heavy domestic carpet. • I have 150 Auralex foam panels that will be attached to the walls to improve the sound. I also have 2 x foam bass traps that I will place in room corners. I plan to experiment with placement of reflective and absorbent surfaces in the room once it is completed. Again, the principle I wanted to adhere to is that no punctures will be made in any internal walls for mounting things – I will use glue or additional freestanding internal timber framing for any interior mounting needs. • Over time I will work on improving the sound of the room. I don’t have the money (or space) available to modify by build to accommodate ant sound improvement features at this time.

Fantastic! Much better! :thu: :D

A 4.8m x 5.4m concrete slab is being laid to a depth of 5 inches

Have you considered embedding electrical conduit in your slab, to make it easy to run cables from here to there? NBot just for electrical nut also for signal: For example, cables from your console to the speakers, or to gear located elsewhere in the room, or even just electrical power to various "things". Some people do that. If you haven't poured the slab yet, it's worth considering. Just make sure to tie the conduit down really well, as it has a tendency to float in the concrete, as you pour....

a damp proof membrane below the concrete which will lap over the side of the concrete slab and be secured under the 2x4 frame soleplate.

Is that the normal accepted practice where you live? In some places it is more common to run the DPC a few inches up the outside of the studs, to ensure that water is directed outwards correctly.

The two additional rectangle areas on the diagram above will be used to site baffle boxes

Have you considered putting those inside the wall cavities, or in the ceiling space above the room, to save space and simplify things?

I will make a final decision next week on whether the outer wall will be constructed of concrete block instead of double thickness chipboard.

Both will work, but those are two very different scenarios, both acoustically and also construction-wise. If you go with concrete block then you should be looking at IR586 and BRN-217, instead of IR761. However, chipboard is no use for external wall surfaces, nor much use for interior walls either! It doesn't have the integrity to stay together or provide useful structural strength, nor does it have the mass to be useful for isolation. I'd strongly suggest that you reconsider, and switch to either OSB or marine grade plywood for your outer sheathing. OSB has a great track record here, and isn't too expensive. Marine plywood might be cheaper, or it might be more expensive, so consider that when you decide which to use. But don't use chipboard!

However the other benefit of using block will be at least a sense of it being more robust;

Stud framing is excellent, structurally. There's a few million stud-framed houses around the world that have been standing up just fine for many, many years! No problem at all, if designed and built properly. In either case (block or framed), as long as you build it well, there should be no issues with structural integrity.

given that I’m using single beams to construct the ceiling and roof off the two independent room walls.

I'm not sure what you mean by "single beams": Are you saying that your roof trusses won't have collar ties on them? They really should! Spanning 4.8m without ties is going to put a lot of outward pressure on the wall tops... I'd strongly suggest that you buy or site-build proper trusses with some form of cross bracing, no matter how you build the walls! If you choose not to do that, at the very least get a structural engineer to OK your roof truss design. There are some pretty major forces going on in roof trusses, trying to crush your walls and also to spread them apart. They need to be dealt with properly in the design. It's not just the dead load, either: the live load from environmental factors can impose huge additional stresses and tensions that need to be directed into the walls correctly, or dissipated within the structure of the truss itself.

Some changes (ie, chipboard and OSB instead of plasterboard on external frame).

You realize that if you do that then you will not get the same results? You can't substitute materials and hope to get something similar! It is a specific tuned system that was tested there. 16mmm chipboard does not behave like 16mm Type X drywall, and neither does it behave like 16mm OSB or 16mm plywood. Substituting materials changes the tuning, and therefore the isolation. That's why there are hundreds of combinations that were tested individually in IR761, and you can see in some cases that even minor changes can have major effects on the outcome. If the combination you choose is not in the paper, then you are on your own as to how it will perform! You can guesstimate or extrapolate from other tests, but you'll never know in advance what the performance will REALLY be like, until after you built it.

The framework will be constructed using 4 x 2 untreated timber.

I think you mean "2x"4, not "4x2"? Or maybe that's a British thing? Most places around the world refer to lumber by the shortest dimensions first (eg, "2x4", "2x6", "2x8", etc.) If you ask for 4x lumber in most building supply stores, they are thinking of larger things... Avoid confusion by using the same terminology as everyone else. Unless, of course, that really is the way they are referred to in the UK?

soleplate will be secured to the slab with the DPM folded over the top and then tacked onto the top of the soleplate.

Hang on a sec! Above you said it would go UNDER the sole plate, but now you say it is going OVER the sole plate? So which is it? Also, is that an approved method in the UK? Having your untreated studs rest directly on top of a waterproof membrane doesn't seem like a good idea to me: any water (eg, condensation) that happens to accumulate down there will puddle in the dimple created by the stud, and rot the stud! As I mentioned before, DPC (DPM) is usually run up the outside of the studs a few inches, underneath the moisture barrier (building wrap) and sheathing, in order to drain any water outwards, not keep it puddled inside...

I will secure the soleplate with tapcon type frame anchors – 5 on each side of the frame, spaced evenly.

That's only one ever meter. Not so good. Is that OK by UK code? Also, since you are pouring your own slab to start with, why not just embed proper framing anchor bolts directly into the concrete as you pour it? Personally, I like to have one anchor bolt in each stud bay, if possible, which means at least two per meter, but maybe that's just because I'm paranoid about earthquakes.... :)

I will be using decking screws, not nails for all framing.

Why? Is that permitted by UK building code? Screws are more brittle than nails, and the stress of inserting them can create fatigue, meaning that they are weakened and tend to fail more easily under tension than nails do. Screws are fine for decking and siding, but I think you'll find that they are not allowed for trusses or joists, or structural members in general. Nails or bolts are usually the only permitted fasteners. If screws are allowed, the schedule is probably denser, meaning that you need more of them... Screws are also more expensive, and take a lot more time to do. With a nail gun, I can finish framing an entire room in the same time it takes you to frame half of a single wall with screws...

• On the front facing wall there will be a door and window, which will have additional uprights and noggins in the frame to create / support the opening.

Right: The general rule here for studios is to have three studs on each side of the door, to handle the stresses and tensions that arise from the huge weight of the doors. Usually that consists of a jack and two kings, with a cripple above the header to continue the load-bearing path of the jack, plus other cripples to maintain the same spacing as the rest of the wall, for the sheathing.

• The outer frame height will be 240cm at one side; and 220cm at the opposite side (to create a very small roof gradient).

That's not the right way to do it. All of the walls should always be the same height, and the gradient of the roof is defined by your trusses, not by the walls. You don't want your top plates to be tilted! You'd never manage to tie them together safely at the corners! (One horizontal, the other angled downwards...) For the end walls, you'd also have to take the time to cut the top of each stud at the correct angle, and they'd all be different lengths so you'd need to measure and cut each one individually, instead of gang-cutting them all. You'd have to cut your sheathing at the same angles too: a nightmare! I think you'll also find that code does not allow that anyway: Have you submitted your framing plan for approval already?

sketchup has defeated me I’m afraid…

Google "sketchup tutorial"... :)

The roof boards will protrude over the edge of the frame by 10cm.

What are you going to use for your roof deck? Here too, I would definitely not use chipboard: it does not hold up well in that type of application. Once again, OSB and plywood are the preferred choices.

I will paint the OSB with exterior contract paint to give some basic weatherproofing.

I wouldn't do that. Rather, I would warp the building with Tyvek or something similar, then put the siding on.

featheredge boards (here) will be applied onto 1x2 uprights spaced roughly 1m apart that I will screw (to a shallow depth) and glue onto the exterior OSB.

That would create a third leaf, which is bad acoustically. That would damage your low frequency isolation. Also, I though Feather Edge was meant only for fences? I didn't know you could use it for siding. I guess you could, but is that done commonly in the UK?

I don’t want to penetrate the OSB with screws,

Why not??? That's what it is there for! As long as you make sure that your screws go all the way through and into the studs, you are fine. That's the correct way to do it.

so just using glue would be preferable if it holds. Any thoughts on this?

My thought is very simple here: NO!!! :) Gluing something to a painted surface is asking for disaster anyway, and gluing siding to a building is just asking for trouble. Things can be screwed and glued, or nailed and glued, or bolted and glued, or even glue laminated (if you have the equipment to do it), but just slopping some glue on a vertical surface than slapping a few planks on top, is not a good idea.

• The outer frame will have a flat roof, with a gradient of 1:24.

Huh! ? :shock: How can it be "flat" and also "have a gradient"??? One or the other, but not both. Your diagram shows a shed roof, not a flat roof, so I guess that's what you are talking about?

All of the roof boards will overlap the edge by 10cm.

What will you use over the roof deck to prevent water penetration? What will the final surface of the roof be? How will you attach it?

The roof will have 8x2 joists.

Roofs don't have joists: the have rafters, beams or trusses. Ceilings have joists, but roofs have trusses. I'd suggest just buying ready-made trusses that have the right angle on them, or site-building them in a jig, to keep them all the same.

They will be spanning a wide area (480cm) but from what I’ve read, it will be structurally ok

RED FLAG! BIG ONE! That roof is going to be above your head. It is going to weigh many hundreds of kilograms. Phrases like: "from what I've read" and "I think" and "feels appropriate" are NOT good omens for it being safe! Do yourself a BIG favor, and get your design checked and approved by a qualified structural engineer. You will likely find that your municipality requires the signature of a certified structural engineer in order to even accept your application for the building permits. You can't guess about things where your life is at stake....

• The inner frame will have the same construction approach as the outer one; but studwork will be centered ‘opposite’ to the outer frame.

It doesn't need to be, and in fact should not be: The first stud after the corner on any wall should be centered at 40cm from the corner, and the following studs should all be spaced 40cm OC, for a very good reason: so that you can put the drywall/OSB/plywood/whatever on! If you don't have the fist stud in the right place then you'll have to wast time and materials cutting your drywall/OSB/plywood/whatever to fit the studs. It's much better just to have the studs in the right place to start with... And since the inner-leaf will not be exactly 40cm offset from the outer leaf, the studs will not line up with each other. Nor do they need to.

• The inner frame ceiling will also have 8x2 rafters spaced in the same way;

The inner-leaf has a ceiling on it, not a roof, so it has joists, not rafters.... Terminology is important in construction! Also, did you check that 2x8 is the correct size here? Did your structural engineer OK that? Will it support the live and dead loads? What deflection did you use for calculating that?

leaving a 5cm air gap between the lowest point of the outer frame.

Have you considered gaining more ceiling height by interleaving your ceiling joists between the roof trusses?

The frame height will be 205cm (to under the double top plate)

Wall framing height is measured from the bottom surface of the sole plate to the top surface of the upper top plate, so your inner-leaf wall height will be 213cm. If you have joist hangers on a 213 cm wall, with 2x8 joists and 2 layers of 16mm drywall, then your final ceiling height will be only 192cm. That's pretty darn low! You can't even get a standard door under that, since they are normally 210 high! You'll have to chop at least 20cm off any standard door or frame to make it fit, and a studio with a 1.9m ceiling is going to be pretty bad acoustically. By the time you add the necessary acoustic treatment to your ceiling, and lighting, and maybe install some laminated flooring, your final height will be getting pretty darn close to 170 cm.... that's REALLLY low. Is there a reason why you cannot build this whole structure a lot higher, so you can end up with a room where you don't have to crouch down to get under the door header? Why not make the roof 70cm higher so you can end up with a final inner-leaf headroom of about 250cm? I honestly can't see a room with headroom of 1.7m as being usable for a studio, either acoustically or practically.

I will insulate each of the independent stud frames using 10cm low density fibreglass insulation.

Why low density? It might be cheaper, but that doesn't make it the right choice, acoustically. If you are going to use fiberglass insulation then the correct density is 30 kg/m3, give or take a couple. If you decide to switch to mineral wool, then the correct density would be about 50 kg/m3. There is a correct density for each type of insulation, and each application.

• I have 2 x large heavy duty fire doors, sized 1980mm x 864mm.

... which are very nice, but will have to be cut down considerably to fit under your very low ceiling....

• I will use 3 x heavy duty hinges for each door.

I'd suggest using four heavy-duty hinges on those doors. They will be HEAVY! And they need to be supported perfectly, so that they cannot ever sag or droop when they are opened or closed, as that would mess with the seals. Use oversize hinges and extra long screws, and work very carefully when you mount them.

Aside from caulking any non-moving parts I haven’t figured out what else to do to minimise flanking through door hardware at the moment. Thoughts appreciated.

The general recommendation is to not use any lock that requires drilling a large hole through the door! This is a self-contained external outbuilding in your garage, so you don't have a lot of options for the outer-leaf door, and you pretty much have to have some type of through.door hole. But the inner-leaf door does not need any type of lock at all. Just an automatic closer and a simple pull handle on the inside is plenty, maybe with a simple latch of some type, or even better, a magnetic catch.

• I have 4 sheets of 6mm laminated glass, sized 1936mm x 676mm. These will be doubled up, and installed parallel / facing each other in the outer and inner frame.

:shock: :? That sounds like a FOUR LEAF window to me! Pretty bad for low frequency isolation! Maybe I misunderstood, but it sounds like you are planning to put two of those panes in the outer-leaf with a gap, and the other two in the inner-leaf with a gap, which implies three air gaps and therefor four leaves. Not good... However, your diagram only seems to show one pane of lamented glass, even though the label says "2 x", so that's very confusing!

• The window frames in each wall frame will not touch each other, but I will tidy up the internal gap in between the frames by attaching a black neoprene strip all of the way around to effectively close the gap between the two sections of 6x2. I’ll put a few sachets of silica gel under the strip.

If you put the desiccant underneath a layer of rubber, then it is no use at all! Rubber is waterproof, so the desiccant would never be able to do its job, since it would never be exposed the the water it needs to adsorb...! The best way to do this is to make a tray from something soft like Homasote or thick cork, cut a shallow "pan" in it to hold the desiccant, put a thin layer of insulation (such as 1" of OC-703) over it, then wrap the entire thing in black cloth, and place it in the gap between the two frames. If you make it just the right size, and can stay in place with just pressure-fit.

I have therefore taken the view that a comprehensive HVAC system isn’t a priority.

Then you have taken the wrong view! :) You will be inside a hermetically sealed shell that is inside a second hermetically sealed shell, so no oxygen will be able to get in, and no CO2 will be able to get out. Humidity (exhaled by you) also has no place to go. No heat will be able to get in or out either, since there will be multiple layers of very efficient thermal insulation around you on all sides. So in essence you will be wrapped inside two plastic bags with thick blankets piled on top... And you will have lights in there (that generate heat) and equipment (that generates heat) and yourself (that generates heat).... I'm assuming that you like to breathe, and like to be at a comfortable temperature, and I also assume that you like your equipment to work well and not burn out when it overheats.... So I'd suggest that you need to re-think your plan here! You will need a small HVAC system that can cool the room and keep humidity under control, as well as a ventilation system that provides you with enough oxygen and fresh air to keep you alive, and removes the same amount of CO2 and stale air. You need to calculate all those, of course. You can't guess.

vents will be placed low down in my room (approx. 20cm upwards of the floor).

They won't remove the stale air then! Stale air is hot: it rises. It is up near the ceiling, not down at floor level. Your inlet vent could be low down, if you want, but the exhaust vent should be high up, preferably in the ceiling.

• I will build 2 x external baffle boxes, sited on the 120 x 35cm concrete pads shown on page

As I mentioned before, it's a lot easier to build them into the wall cavity, or the ceiling space, and save the expense and complication of those extra pads.

The baffle boxes will each house a 125mm vent axia Powerflow duct fan

Which one? There are several models on that page you linked to, ranging from 0.059 m³/s to 0.42 m³/s. What rate do you need for your room? And what will the static pressure be?

One will push air in, and the other will push air out.

You do not need two: your room is a sealed system, so you only need one fan. It can either push air into the room at the inlet, or suck it out at the outlet. It doesn't matter which, but you only need one. If you had two, then trying to balance them would be a huge pain as well, so one is much simpler. However, it does need to be sized correctly for your room! You can't just throw any old fan in: you have to do the math to determine what flow rate you need, and find a fan that can move that amount of air when running into the static pressure that your system will produce. Also, if you place your fan on the room side of the silencer box, then that's pretty pointless! It wont silence anything like that! You'll hear the fan running, loud and clear. The fan should be OUTSIDE, the box, not inside it, and should be right on the far end, at the exit port. And don't use an inline fan for that: that's not what the are meant for. Use a proper outdoor duct fan. Fantech makes some good ones.

• I couldn’t draw in the snaking duct, but the idea is that the duct snakes between the gaps in the board.

That would be very hard to build, and is not necessary at all! That's a very complicated way of doing something that is actually quite simple. Here is the correct way to build silencer boxes: viewtopic.php?f=2&t=15430&start=45 viewtopic.php?f=2&t=1929&start=74 viewtopic.php?t=8425&start=2 viewtopic.php?f=1&t=11542&start=5 viewtopic.php?f=2&t=9761&start=0 viewtopic.php?f=2&t=11485&start=98 viewtopic.php?f=2&t=11508&start=157 viewtopic.php?f=2&t=13821 viewtopic.php?f=1&t=15378&start=44 viewtopic.php?f=2&t=18202&start=16

All of the cavity is filled with rockwool.

For all of your ducting, you should NEVER use plain insulation. Not rockwool, and not fiberglass. Use ONLY proper duct liner. The airflow will ablate normal insulation, and the fibers will end up blowing all over you, and your equipment, and your room....

• If I need heating I will use an oil filled radiator in the room. I also have a dehumidifier that I will use frequently to remove excess moisture.

You won't need either of those, if you install a proper mini-split system. It will heat the room when it is cold, cool it when it is hot, and control the humidity as well. And it will do so very quietly, without needing to be emptied several times per day...

cable will run directly into the studio via a flexible pipe that will be inserted into the concrete slab when it is laid.

I doubt that electrical code will permit you to run flexible electrical conduit in a slab! As far as I know, code only allows proper rigid metal or PVC conduit embedded in concrete.

I will then fill the remaining space in the pipe (with sand?) and seal / bury it.

:shock: :?: Why? The entire purpose of conduit is to allow you to pull wiring through, and then take it out later, replace it, add more as needed. You can't do any of that if it is filled with sand!

• On the inside of the studio, cable will be run through self-adhesive cable trunking. Nothing will be attached to the inner side of the room with screws or nails.

How do plan to attach your outlets, switches and lighting boxes then? I've never seen any of those that can be attached only with adhesive. They all need screws, as far as I know. Does code even allow adhesive for attaching boxes? It does for duct, I'm sure, but for outlets and switches? I doubt it.

• The room will be carpeted with underlay followed by a heavy domestic carpet.

Bad idea. Very bad. Carpet does the exact opposite of what you need. Take a look at photos of world-class studios, such as Abbey Road or Galaxy, and see how much carpet you can find on the floors: The answer is; "Zilch!": There's a reason for that: it totally messes up both the acoustics and the psycho-acoustics of the room. Leave your floor hard, and put proper treatment on the ceiling, where it belongs. 10 to 15 cm of OC-703 would be a good choice. You are planning on having a very low ceiling, so you'll actually need more than that: probably 20cm would be a good start.

• I have 150 Auralex foam panels that will be attached to the walls to improve the sound

How will they improve the sound? ;) I have nothing against Auralex, and they do make some good products, but they have to be used correctly. You can't just throw around some foam on the walls any old place, and expect it to make the room sound good. The right type of treatment needs to go in the right place, if you hope to get a usable studio...

I also have 2 x foam bass traps that I will place in room corners.

That's a very small room! It will need a lot more than just a couple of foam bass traps. A HUGE lot more!!! Large superchunks in all the vertical corners, at the very least...

I plan to experiment with placement of reflective and absorbent surfaces in the room once it is completed.

There's no need to experiment: It's much better to just follow standard practices for initial placement of basic treatment, then do an acoustic test of the room to see which problems still remain, which of those can be treated or are worth treating, then place the necessary treatment. And you certainly won't need many reflective surfaces in a room that small, with a really low ceiling! You will need roughly 360 sabins of absorption for that room, to bring it within AES and ITU specs. You only have about 780 square feet of surface area inside the entire room, so about half of the total surface area will have to be perfect absorption. The floor is out, of course, leaving only 580 ft2. Doors and windows probably knock that back to around 500, and speakers, trim and other issues witll take it down to about 450. So about 80% of all the wall and ceiling surface will need absorption. That leaves practically no exposed reflective surfaces, and you certainly won't need to add any more!

Again, the principle I wanted to adhere to is that no punctures will be made in any internal walls for mounting things

I still don't understand why not. That's what the studs are there for! To nail things into. If you want to mount something, just nail through the wall surfaces into the stud, and you have no problems. You would only compromise your isolation by making a hole in the wall surfaces that REMAINS as a hole, allowing the passage of air from one sire to the other. Putting a nail into the stud does not do that, since the nail fills the hole and stays there, and is embedded in the stud anyway, so isolation is not compromised.

• Over time I will work on improving the sound of the room.

What would be your plan for doing that? There's a limit to what can be accomplished acoustically in any room, based on the dimensions. In a small room such as yours with a very low ceiling and poor modal ratio, you'll reach that limit fairly quickly, just with standard basic treatment. After you get to the limit (or close to it), there is nothing further you can do to improve the sound of the room. Simple laws of physics prevent that. The only way to improve the sound of the room, would be with a bulldozer! :) In other words, you would have to change the size of the room to make it better: you would have to make it bigger, in one, two or all three of the dimensions. There won't be much opportunity for improvement in a small room like that, once the basic treatment is in, and perhaps one or two rounds of "test-treat-test-treat" with REW. But with a room like that, you'd be into "diminishing returns" pretty fast, where the cost and complexity of each additional treatment device goes up exponentially, while the benefits only go up linearly. That's the price we pay for trying to fit studios into small spaces! There's only so much that can be done before hitting the wall imposed by physics.... - Stuart -

Many thanks for the comprehensive and well informed reply Stuart. There is lots of food for thought that you've given me. I've been working away all week and have returned home with the slab completed. The rest of the build isn't going to start until I've had a long hard think about a number of things you've pointed out.

Have you considered embedding electrical conduit in your slab, to make it easy to run cables from here to there? NBot just for electrical nut also for signal: For example, cables from your console to the speakers, or to gear located elsewhere in the room, or even just electrical power to various "things". Some people do that. If you haven't poured the slab yet, it's worth considering. Just make sure to tie the conduit down really well, as it has a tendency to float in the concrete, as you pour....

I did consider that, but I'm a few days too late as its laid. I thought that doing the conduit through the baffle box would give me a better chance of improving the performance of the conduit it it didn't work too well. Thats my first regret then - I'm sure it wont be my last! ....a damp proof membrane below the concrete which will lap over the side of the concrete slab and be secured under the 2x4 frame soleplate.

Is that the normal accepted practice where you live? In some places it is more common to run the DPC a few inches up the outside of the studs, to ensure that water is directed outwards correctly.

That makes sense. I'll do that instead. ....The two additional rectangle areas on the diagram above will be used to site baffle boxes[. quote]Have you considered putting those inside the wall cavities, or in the ceiling space above the room, to save space and simplify things? [/quote] Yes, I considered this, but as I'm really tight on space, I felt building some designated spaces attached would be easier to work with. Time will tell! Photo of one of these below. Shuttering wont be removed and tidied up for another week. ....I will make a final decision next week on whether the outer wall will be constructed of concrete block instead of double thickness chipboard.

Both will work, but those are two very different scenarios, both acoustically and also construction-wise. If you go with concrete block then you should be looking at IR586 and BRN-217, instead of IR761.

Thanks Stuart. Wooden frame it is. Block ended up feeling much more complex given my novice building skills. [/quote] However, chipboard is no use for external wall surfaces, nor much use for interior walls either! It doesn't have the integrity to stay together or provide useful structural strength, nor does it have the mass to be useful for isolation. I'd strongly suggest that you reconsider, and switch to either OSB or marine grade plywood for your outer sheathing. OSB has a great track record here, and isn't too expensive. Marine plywood might be cheaper, or it might be more expensive, so consider that when you decide which to use. But don't use chipboard! [/quote] Thanks Stuart - appreciated. I thought I may get away with it as the 'underlayer', and falsely assumed it would have sufficient mass to replicate plasterboard. I will look at marine ply and OSB options. I suspect 2 layers of OSB will be the cheapest option for me. ..... given that I’m using single beams to construct the ceiling and roof off the two independent room walls

I'm not sure what you mean by "single beams": Are you saying that your roof trusses won't have collar ties on them? They really should! Spanning 4.8m without ties is going to put a lot of outward pressure on the wall tops... I'd strongly suggest that you buy or site-build proper trusses with some form of cross bracing, no matter how you build the walls!

Advice taken - I'll look at cross-braced truss options. My main issue with this though is the extra height this will give my structure. I will have two frames to put independent a ceiling / roof on. Is there a way of combining a cross-braced roof design across my inner and outer frames, to save me having two layers of trusses? ....The framework will be constructed using 4 x 2 untreated timber.

I think you mean "2x"4, not "4x2"?

Quite right - I'll remember that in future.. .....soleplate will be secured to the slab with the DPM folded over the top and then tacked onto the top of the soleplate.

Hang on a sec! Above you said it would go UNDER the sole plate, but now you say it is going OVER the sole plate? So which is it? Also, is that an approved method in the UK? ........As I mentioned before, DPC (DPM) is usually run up the outside of the studs a few inches, underneath the moisture barrier (building wrap) and sheathing, in order to drain any water outwards, not keep it puddled inside.

I've been a bit muddled about how I do this - I'll follow your advice and run up the studs! ......I will secure the soleplate with tapcon type frame anchors – 5 on each side of the frame, spaced evenly.

That's only one ever meter. Not so good..... Personally, I like to have one anchor bolt in each stud bay, if possible, which means at least two per meter, but maybe that's just because I'm paranoid about earthquakes.... :)

Advice taken. We dont have earthquakes often, but 2 per metre it is .... I will be using decking screws, not nails for all framing.

Why? Is that permitted by UK building code? Screws are more brittle than nails, and the stress of inserting them can create fatigue, meaning that they are weakened and tend to fail more easily under tension than nails do....Screws are also more expensive, and take a lot more time to do. With a nail gun, I can finish framing an entire room in the same time it takes you to frame half of a single wall with screws...

Good points, nails it is. I may hire a nail gun for a day to get all framing done that way. ..... On the front facing wall there will be a door and window, which will have additional uprights and noggins in the frame to create / support the opening.

Right: The general rule here for studios is to have three studs on each side of the door, to handle the stresses and tensions that arise from the huge weight of the doors. Usually that consists of a jack and two kings, with a cripple above the header to continue the load-bearing path of the jack, plus other cripples to maintain the same spacing as the rest of the wall, for the sheathing.

Thanks - I'll revise my framing plan accordingly. ..... The outer frame height will be 240cm at one side; and 220cm at the opposite side (to create a very small roof gradient).

That's not the right way to do it. All of the walls should always be the same height, and the gradient of the roof is defined by your trusses, not by the walls. You don't want your top plates to be tilted! You'd never manage to tie them together safely at the corners! (One horizontal, the other angled downwards...). For the end walls, you'd also have to take the time to cut the top of each stud at the correct angle, and they'd all be different lengths so you'd need to measure and cut each one individually, instead of gang-cutting them all. You'd have to cut your sheathing at the same angles too: a nightmare! I think you'll also find that code does not allow that anyway: Have you submitted your framing plan for approval already?

I'll have to revisit this plan and find a more appropriate way to build the roof. Incidentally my build is out of scope of building regulations due to the size / the fact it is essentially an outhouse rather than a living space. I'm not a builder (by a long shot) and I want to avoid dangerous errors. Your advice therefore appreciated

What are you going to use for your roof deck? Here too, I would definitely not use chipboard: it does not hold up well in that type of application. Once again, OSB and plywood are the preferred choices.

OSB is the plan. .........I will paint the OSB with exterior contract paint to give some basic weatherproofing.

I wouldn't do that. Rather, I would warp the building with Tyvek or something similar, then put the siding on.

Thanks - I'll look at Tyvek options ....featheredge boards will be applied onto 1x2 uprights spaced roughly 1m apart that I will screw (to a shallow depth) and glue onto the exterior OSB.

That would create a third leaf, which is bad acoustically. That would damage your low frequency isolation. Also, I though Feather Edge was meant only for fences? I didn't know you could use it for siding. I guess you could, but is that done commonly in the UK?

My thinking here was that featheredge is sufficiently thin to 'not count' as a third leaf? I want the building to look decent, particularly as its a residential garden. It is commonly used for siding in the UK ..... I don’t want to penetrate the OSB with screws

Why not??? That's what it is there for! As long as you make sure that your screws go all the way through and into the studs, you are fine. That's the correct way to do it.

Understood. I got it into my head that additional screwing into the external panels would create vulnerabilities. I'll get a stud-finder and do as you suggest. .......... The outer frame will have a flat roof, with a gradient of 1:24.... They will be spanning a wide area (480cm) but from what I’ve read, it will be structurally ok

RED FLAG! BIG ONE! That roof is going to be above your head. It is going to weigh many hundreds of kilograms. Phrases like: "from what I've read" and "I think" and "feels appropriate" are NOT good omens for it being safe! Do yourself a BIG favor, and get your design checked and approved by a qualified structural engineer

Point taken - thanks. Yes, I need to do more work on my roof solution .......The inner frame will have the same construction approach as the outer one; but studwork will be centered ‘opposite’ to the outer frame.

It doesn't need to be, and in fact should not be: The first stud after the corner on any wall should be centered at 40cm from the corner, and the following studs should all be spaced 40cm OC, for a very good reason: so that you can put the drywall/OSB/plywood/whatever on! If you don't have the first stud in the right place then you'll have to wast time and materials cutting your drywall/OSB/plywood/whatever to fit the studs. It's much better just to have the studs in the right place to start with... And since the inner-leaf will not be exactly 40cm offset from the outer leaf, the studs will not line up with each other. Nor do they need to.

Thanks - that makes sense. .........The inner frame ceiling will also have 8x2 rafters spaced in the same way

The inner-leaf has a ceiling on it, not a roof, so it has joists, not rafters.... Terminology is important in construction! Also, did you check that 2x8 is the correct size here? Did your structural engineer OK that? Will it support the live and dead loads? What deflection did you use for calculating that?

Will revisit the roof in its entirety. 8x2 was suggested by the builder who laid my slab for me

Have you considered gaining more ceiling height by interleaving your ceiling joists between the roof trusses?

I haven't - but this sounds like an attractive option. I will do some research on this - thanks.

The frame height will be 205cm (to under the double top plate)

Wall framing height is measured from the bottom surface of the sole plate to the top surface of the upper top plate, so your inner-leaf wall height will be 213cm.

Is there a reason why you cannot build this whole structure a lot higher, so you can end up with a room where you don't have to crouch down to get under the door header? Why not make the roof 70cm higher so you can end up with a final inner-leaf headroom of about 250cm?

I am trying to avoid planning and building control regulations; primarily to reduce costs. We have permitted development rights in the UK. I can build an outbuilding of this size without needing any kind of permit. However the whole building must not exceed 2.5m in height. If I can find a way if integrating the roof trusses with the ceiling joists this might give me more head hight. ........I will insulate each of the independent stud frames using 10cm low density fibreglass insulation.

Why low density? It might be cheaper, but that doesn't make it the right choice, acoustically. If you are going to use fiberglass insulation then the correct density is 30 kg/m3, give or take a couple. If you decide to switch to mineral wool, then the correct density would be about 50 kg/m3. There is a correct density for each type of insulation, and each application.

Thanks - I will revise this. ..........I have 4 sheets of 6mm laminated glass, sized 1936mm x 676mm. These will be doubled up, and installed parallel / facing each other in the outer and inner frame

it sounds like you are planning to put two of those panes in the outer-leaf with a gap, and the other two in the inner-leaf with a gap, which implies three air gaps and therefore four leaves. Not good...

There will be only 1 air gap, and that would between the two masses of glass. Each mass of glass would be 2 sheets placed next to each other. Ideally these would be bonded together with another interlayer so its one thick pane of glass; but my thinking was that if they fit snugly into the frame next to each other, having them donded together wouldnt make too much difference anyway? An additional interlayer would help with further isolation, but its not a possibility to bond glass at home from what I can find out. ....... I have therefore taken the view that a comprehensive HVAC system isn’t a priority.

I'd suggest that you need to re-think your plan here! You will need a small HVAC system that can cool the room and keep humidity under control, as well as a ventilation system that provides you with enough oxygen and fresh air to keep you alive

Again, thanks for the good advice. I need to replan this from what you have said. I managed to pick up two lightly used fans I mentioned at a bargain price, hence planning to utilise them. ....... cable will run directly into the studio via a flexible pipe that will be inserted into the concrete slab when it is laid.

I doubt that electrical code will permit you to run flexible electrical conduit in a slab! As far as I know, code only allows proper rigid metal or PVC conduit embedded in concrete.

It was PVC conduit that I was referring to (in the wrong terms). I have had my slab laid and ended up not doing this though. ......the principle I wanted to adhere to is that no punctures will be made in any internal walls for mounting things

I still don't understand why not. That's what the studs are there for! To nail things into. If you want to mount something, just nail through the wall surfaces into the stud, and you have no problems.

Thanks - I'd clearly misunderstood - thanks for clarifying Thanks again for all of the great advice - very much appreciated.

Here's a quick thought: If you are limited to a total height of 2.5m, then why not do a flat roof? That will allow you to have plenty of height inside for all you need. Also, if you do concrete block walls, you could do a "beam and block" flat roof (google it), which entirely obviates the need for trusses, decks, framing, etc., and maximizes your internal space. All that you loose is the thickness of the beams. You could then do your inner-leaf as normal framing, and do the ceiling inside-out to maximize headroom. It's a pity you poured your slab already: there's another simple way you could have gained much more headroom: the 2.5m limitation refers to "height above grade" not "height above slab", so by digging down 20cm then pouring your slab below grade, you could have gained another 20cm in ceiling height inside. But it's too late for that now... (It's no big deal about the conduit not being in the slab: that can all go in the inner-leaf framing.)

I may hire a nail gun for a day to get all framing done that way.

You'll probably need it for more than a day, and definitely keep the compressor for more than that, even without the nail gun: compressors have numerous uses on a construction site... Even if it is just blowing out the dust before you seal, or before you paint, or just to keep things looking clean! But there's lots of pneumatic tools and accessories that you could use. Take a look around the pneumatics area of your local hardware store...

My thinking here was that featheredge is sufficiently thin to 'not count' as a third leaf?

Mass is mass, and air gap is air gap. The lower the mass, the higher the resonant frequency (which is bad). The smaller the air gap, then higher the resonant frequency (which is bad too). So thin wood over a small air gap is bad on two counts! The idea is to get the MSM resonant frequency down as low as possible, ideally one octave below the lowest frequency that you need to isolate. Anything that raises the frequency is a bad idea.

I want the building to look decent, particularly as its a residential garden.

with concrete block outer leaf, you could just render (plaster) the outside, then paint it. You could even shot-crete it with your trusty compressor, then spray paint it with your trusty compressor... Lots of options! :)

Each mass of glass would be 2 sheets placed next to each other.

Then how will you prevent them from vibrating against each other at the coincidence dip frequencies, and making a hell of a racket, as well as trashing your isolation? :)

my thinking was that if they fit snugly into the frame next to each other, having them donded together wouldnt make too much difference anyway

? Just because they are held together around the edges does not mean that the rest of the panes is also held together! The middle can easily vibrate. There's plenty of scope for one or both of those panes to vibrate in sympathy in any number of resonant modes, out of sync with its neighbor, and since they are in direct contact, that would create a "chattering" sound at those frequencies. HUMMMMMM.... BZZZZZZZ.... DGEEEEEEE!!!!!

Ideally these would be bonded together with another interlayer so its one thick pane of glass;

Right, but I'm not aware of any system that allows the home DIY'er to do that all by himself. Laminating large sheets of glass requires high pressures, high temperatures, and a clean environment. It's not something you can do in your kitchen.

but its not a possibility to bond glass at home from what I can find out.

Right. This might be one area where you don't have much choice but to "bight the bullet", and purchase proper thick laminated glass. If you can't afford laminated, then even non-laminated glass is a good option, provided it is thick enough. Hint: Some modern furniture is made using very thick glass: you might be able to find second hand tables that you could salvage the glass from. You could adjust the size of your windows to fit whatever glass you find. Hopefully you can find two identical tables, cupboards, or whatever with very thick glass, so you can do both leaves the same. You might even get really lucky, and find an old bank that is being demolished, so you can pick up the bullet-proof glass from the teller cubicles at a cheap price. Nothing better than that! How thick does it need to be? Simple rule here: it needs to be thick enough that the surface density of the wall is maintained. Or at the very least, thick enough such that the MSM resonant frequency does not rise high enough to be an issue (remains at least one octave down from the lowest frequency you need to isolate).

I managed to pick up two lightly used fans I mentioned at a bargain price, hence planning to utilise them.

Once again, it's not just "any old fan" that you can use. You need to do the math to make sure that you are getting the correct number of room changes per hour for your sized studio in your area with your occupancy, with the fan moving the correct volume (flow rate) at the correct speed (slow velocity). Fans are designed to move a certain amount of air at a certain speed, when facing a certain amount of resistance. Your duct system, silencer boxes, registers, and the room itself all provide a certain amount of static pressure and friction resistance to the flow of air. Your fan MUST be able to work with that exact amount of resistance. If there is too much air flow resistance ("back pressure" then the fan will be overloaded, run too slow, move too little air too slowly, make a lot of noise, suffer blade stall, overheat, and burn out. If there is not enough resistance, then the fan will over-speed, move too much air too fast, overheat, make a lot of noise, and burn out. Find out what flow rate your fans are designed to produce at what static pressure, then check what static pressure your system will create. If the flow rate, flow velocity and static pressure are not within the range that your fan is designed for, then you'll have to ditch the fan and get the right one for the job. Saving money by getting second hand materials is laudable... Provided that they are the right materials for the job!

The rest of the build isn't going to start until I've had a long hard think about a number of things you've pointed out.

:thu: Very smart move! I'd REALLY encourage you to have another go at SketchUp: work through some of the tutorials that are on YouTube until you get the hang of it, then do the entire design in Sketchup, including all the details, complete. That's the ONLY smarte way of making sure that everything is in place, that it all fits and works together, that it all makes sense, and that it will sound good and also isolate to the level you want. A very smart acoustician here on the forum has said that building a home studio is 90% design and 10% construction. Very true! If you do it in SketchUp, then you are basically building it twice: once using electrons and bytes in your computer, which are dirt cheap and dead easy to change as often as necessary until you get it right. And the second time with real building materials that are damn expensive, and a whole lot harder to change! If you build it right the first time, then the second time is a piece of cake. Yeah, it make take you weeks, or even months to get it right in SketchUp, and it's really sad to see that nice slab sitting out there in the back yards, just begging to have something built on top, but that's a small price to pay in order to get the best possible studio you can, and the lowest cost... :) If you really can't (or don't want to) do the design yourself, then consider paying someone else to do it for you: That's money well spent, considering the cost of having to knock something down after you built it, then re-build it right the second time... - Stuart -

Hi all I'm still finalising my redesign, but wondering about the external wall. Would it be a really bad idea to use plasterboard as the base layer, followed by OSB3 as the second layer? Next will be tyvek, followed by cedar cladding. All of the plasterboard will be well covered and sealed up, so I'm thinking that it would survive outside? My rationale for this is insulation effectiveness and cost. I realise that wet plasterboard degrades, but I'm thinking that under all of the other layers, environmental impact to the plasterboard would be negligible. Any views? Cheers James

Just have a couple of questions about HVAC design: 1: I am using 125mm ducting. In designing my baffle boxes, is there a formula I can follow for this to ensure that the sizes are correct? 2: Would there be any benefit to me placing two inline fans on the same inlet duct? I will have around 4m of ducting that will be running vertically up and down more than horizontally, with a baffle box inside the studio before the inlet vent, and outside before the exhaust vent. I'm thinking that using two fans (which I have already) may help to keep the air moving?

1: I am using 125mm ducting. In designing my baffle boxes, is there a formula I can follow for this to ensure that the sizes are correct?

The internal cross sectional area of your boxes must be about double the cross sectional area of the inlet duct and exit ducts. The change in cross section must be sudden. So since you are using 5" duct, the internal cross sectional area of your boxes must be at least 40 square inches. So make it at least 6" x 7" internally (not including the duct liner!) To allow for the 1" duct liner, your boxes would need to be at least 8" by 9" inside, in order to leave 6" x 7" free area once the duct liner is in place. However, that doesn't sound correct. It sounds too small for a typical studio. To check that you have the correct exchange rate, flow rate, flow velocity, duct size, static pressure, cooling capacity, de-humidification capacity, etc. you might find these links useful: http://www.engineeringtoolbox.com/air-c ... d_867.html http://www.engineeringtoolbox.com/air-d ... d_669.html http://www.engineeringtoolbox.com/air-d ... _1736.html http://www.engineeringtoolbox.com/equiv ... d_443.html http://www.engineeringtoolbox.com/laten ... d_245.html http://www.engineeringtoolbox.com/dehum ... d_141.html http://www.engineeringtoolbox.com/stati ... d_658.html http://www.engineeringtoolbox.com/ductw ... _1122.html All of those are very useful, and all of them are also critical.

2: Would there be any benefit to me placing two inline fans on the same inlet duct?

No. You need the correct size fan for the static pressure and flow rate of your entire system.

I will have around 4m of ducting that will be running vertically up and down more than horizontally, with a baffle box inside the studio before the inlet vent, and outside before the exhaust vent. I'm thinking that using two fans (which I have already) may help to keep the air moving?

If you use two fans, you will have to carefully balance the flow rate so they are both moving the exact same identical volume of air, at the exact same velocity. Not easy to do. Since you already know your duct size, that implies that you already know what flow rate and flow speed you need. So all you need to do now is to find a fan that produces the correct flow rate, at the static pressure that your system produces. Fans are rated just like that: There is a nominal rating, that shows how much air the fan moves (CFM) with no load, in free space, and then how much air it moves at various static pressures. You need to find a fan that moves the right amount of air at the static pressure imposed by your system. That's the fan that you need. And you only need one such fan: it can go either in the supply duct (the duct that brings fresh air into your room from outside), or it can go on the exhaust duct (the duct that removes stale air from your room). - Stuart -

Here's a question ... If the fan is use in the EXHAUST portion [rather than the INTAKE] ... might the overall system be quieter in principle ? This is just a generic question of sorts, as many things play a part of all this. Reading through this portion of the thread cause me to wonder out loud about this. I know I'll be also dealing with this aspect for my new build ... but I already know that I've much research ahead to get this done proper and most effective. Keeping room noise to an absolute minimum is essential. My Mr. SLIM duckless AC is around 21-23dB [A-weighting]. The computer fan is the noisiest compnent in the whole room, and that is destinied to be placed outside the room with connection lines running in. Can these needed fresh air supply/exchange [with silencers] achieve these low noise levels ? While still maintaining the high TL [in and out] of the room [+60dB TL]? Excuse my posting on 'Your' thread ... but I hope you see it complimenting what you too are needing to do. Thanks !

If the fan is use in the EXHAUST portion [rather than the INTAKE] ... might the overall system be quieter in principle ?

That's the way I prefer to do it, actually! :) I usually try to put the fan on the far end of the exhaust duct, right where it ends. And since that is usually outside, I normally use an exterior extraction. That places it as far away as possible from the room. Theoretically, there is a small advantage from having the fan downstream, rather than upstream, since the airflow itself is "taking the sound of the fan away", to a certain extent. I'm not sure exactly how much that helps, in terms of dB reduction in fan noise, but hey, I'll take anything I can get!

Can these needed fresh air supply/exchange [with silencers] achieve these low noise levels ? While still maintaining the high TL [in and out] of the room [+60dB TL]?

Yup! If you design the system right, and build it right. The boxes / ducts / registers / fans / filters all need to be sized correctly to move the right volume of air at low speed, so all of the cross sections need to be as large as you can make them, within reason. The transitions into and out of the silencers need to be sudden, to enhance the impedance mismatch, the boxes need to be made from heavy materials (mass), have several baffles, be lined with proper duct liner, and the ducts connecting the silencer boxes need to be as long as you can make them (also within reason). Also, the last part of the duct in the room needs to be as smooth and featured as possible for a fairly long distance just before it reaches the register, and the register itself needs to be of the low-noise type, with a large percentage of open area, in order to minimize turbulence and air movement noise. Etc. Lots of stuff to take into account, but yes, it can be done. - Stuart -

thanks again Stuart I'm wondering about attaching my tyvek. The staple gun I have only fires 10mm staples or larger. The board I'm using on the exterior is 11mm OSB; 2 layers. I'm wondering though if firing 10mm staples all over the 11mm OSB may risk compromising the integrity of the outer layer of OSB? Also, a power cable question. I'm thinking of running my power cable inside a tube into my studio. As there will be air gaps inside the tube, should the tube exit via a baffle box? Could the HVAC baffle box be used for this? Cheers James

Loving this thread so far and learning a lot through it. One question.

Soundman2020 wrote:

Why low density? It might be cheaper, but that doesn't make it the right choice, acoustically. If you are going to use fiberglass insulation then the correct density is 30 kg/m3, give or take a couple. If you decide to switch to mineral wool, then the correct density would be about 50 kg/m3. There is a correct density for each type of insulation, and each application.

This surprised me and has exposed yet another one of my preconceived notions regarding correct practice for studio builds. I'm aware that 50 kg/m3 fiberglass is often used for creating acoustic panels, but I thought that "typical" low density domestic wall cavity batts would be suitable for use inside studio walls. Many of the photos I've seen of studio builds "seem" to use a much lighter grade than 30-50 kg/m3. In my own forthcoming studio build (viewtopic.php?f=2&t=19992) I'll have close to 100 square metres of walls and ceiling to insulate, or should I say, double insulate (as double walls will be built). A heavier grade of insulation like Bradford Supertel (http://bradfordinsulation.com.au/~/medi ... sheet.ashx) would be significantly more expensive than most standard batts, so I just want to confirm this before I get my wallet out. If anyone can link to an appropriate thread in this forum or chime in with some further info, that would be wonderful. Good luck with your build James!

Door locks / closures: Does anyone have any interesting approaches to the door lock issue? I'm trying to avoid any lock cavities / lock related drilling in my doors. Maglocks may be the way forward, but keen to hear of experiences of others Cheers

Probably to late for you as iv not been on the forum for a long while but I was in the same situation as you being in the UK not being able to go higher than 2.5m in height, so I went down around 800mm down in fact :D

sorry I seem to have manage to double post :D

Roguejackal wrote:

Probably to late for you as iv not been on the forum for a long while but I was in the same situation as you being in the UK not being able to go higher than 2.5m in height, so I went down around 800mm down in fact :D

Yes - I would have done that myself too - but going down further was not possible due to that area of my garden comprising very large rocks - went down as far as I could...

.... Just wanted to check my baffle box design too... I'm using 125mm duct and will have 4 of these boxes; two on either end of inlet, and two in either end of exhaust. Any thoughts?

I just have a minute or so for a quick answer, so no time to check your math. But two questions: 1) Is the cross sectional area at all points inside the box at least twice the cross sectional area of the entry and exit ducts? 2) Did you allow for the thickness of the duct liner on all interior surfaces? That isn't show on your diagram, but its important that your calculations of cross sectional area are done from the surface of the duct liner, and not the surface of the box itself. (You do know that you have to line all of the interior surfaces of the box with 1" duct liner, right?) - Stuart -

Soundman2020 wrote:

1) Is the cross sectional area at all points inside the box at least twice the cross sectional area of the entry and exit ducts?

Yes - If the 'baffles' are not included in this calculation. The question slightly confuses me :oops: The baffles divide the box into 3 compartments for air to run through, and each compartment I 'think' would be less than twice the cross sectional areas of the exit and entry

Soundman2020 wrote:

2) Did you allow for the thickness of the duct liner on all interior surfaces? That isn't show on your diagram, but its important that your calculations of cross sectional area are done from the surface of the duct liner, and not the surface of the box itself. (You do know that you have to line all of the interior surfaces of the box with 1" duct liner, right?) - Stuart -

Yes, all interior areas will be lined with duct liner. The adhesive neoprene liner I have is approx 7mm thick.

The question slightly confuses me ... The baffles divide the box into 3 compartments for air to run through, and each compartment I 'think' would be less than twice the cross sectional areas of the exit and entry

That's what I was trying to say: the cross sectional are in each of those "compartments" must be about two (or more) times the cross section of the duct. Think of it this way: the silencer works on may principles at once. One of those is "acoustic impedance mismatch", meaning that due to the sudden change in cross-section where the duct comes into the box, any sound waves coming down the duct will be partly reflected back up the duct by that impedance change, and only partly passed through. In order to be effective, the change in cross section needs to be about a factor of two. (the same applies at the exit: once again, there's an impedance mismatch). OK, that's the acoustic part, but there's also the plain old air flow issue: Because the cross section changes to twice the area, the speed drops to half what it was in the duct (because the flow rate stays the same throughout: we are not compressing any air here!). So now you want to keep that air flowing at roughly the same rate as it moves through the box: If you force it into a "tighter" section (less cross section area) then it has to speed up again. Air that moves faster makes more self-noise than air that moves slower. So you don't want it going faster and slower, faster and slower, faster and slower as it moves through the box. Fast moving air also generates more turbulence than slow moving air, and turbulence also causes noises. Etc. So the ideal is to keep the cross section roughly constant. If the cross section at the entry is 200% the cross section in the duct, then that's what you want to keep all along. Or if it is 150% (not ideal, but sometimes you have no choice), then keep it at 150% all the way.. Or if you manged to get 300% change at entry and exit, then 300% is what you want all the way through. Of course, you don't have to be crazily perfect here: there are variations in area as the flow moves around each baffle anyway, so there's no point in trying to refine things down to tiny percentages. But do try to keep in the ball-park.

Yes, all interior areas will be lined with duct liner. The adhesive neoprene liner I have is approx 7mm thick

Then it isn't duct liner!!! :shock: :!: Duct liner is a very specific product, that is porous (fiberous) with some type of surface treatment to keep the fibers in place, and it is made specifically for lining the inside of HVAC ducts. It is usually 1" thick (25mm) or 2" thick (50mm). You can sometimes find 1/2" liner (13mm), but it isn't very common, and isn't a lot of use. But 7mm? And neoprene? Never heard of that for duct liner!!! This is what duct liner is: https://www.google.cl/search?q=duct+lin ... 40&bih=470 http://www.industrialnoisecontrol.com/m ... -liner.htm http://www.certainteed.com/products/ins ... ial/317383 http://www.armacell.com/www/armacell/AC ... .12.09.pdf If that's not what you have, then return it: it isn't what you need for this application. I almost never use anything less than 25mm for silencer boxes, and certainly not just 7mm. - Stuart -

Soundman2020 wrote:

If that's not what you have, then return it: it isn't what you need for this application. I almost never use anything less than 25mm for silencer boxes, and certainly not just 7mm. - Stuart -

Thanks Stuart - another error from me in ending up with the wrong product. :oops: Have found the right thing now and will get some ordered

Thanks Stuart - another error from me in ending up with the wrong product

:thu: Aren't you glad you found the form, and are posting regular updates? Imagine where you'd be right now without that! It's actually a GOOD thing when you find mistakes in your studio build: It means your studio will be a much better place when it is done, because all the mistakes won't be there! - Stuart -

The framework will be constructed using 4 x 2 untreated timber.

That's just a UK thing. We like to be difficult. :D