Oshman's Garden Studio Build!!!

Hi all, I have been reading this forum on and off for the last two years and while planning a build from scratch in my back garden. This forum has been a great inspiration and i wouldn't have a clue without it. I bought Rod's book last year and gave it a read and from that formed the basis of my design. I'm at the finalization stage of my design and am about to apply for planning permission Fortunately for me my brother is an Architect and has agreed to help me out with the plans,, he's also read the book and used a lot of Rod's guidelines. Also i have a friend in the UK who has built a similar sized studio in his back garden with a similar budget and he's supplied me with some great advice. Unfortunately the space i have to build in is not that large.. 16.07' x 25.26' And it's about 15' away from the neighbors kitchen. My plan is to have a two room build (live room/ control room) with a toilet and kitchenette area. I know it's a lot to squeeze in that space!! Due to the lack of space that i have, and to try and give both rooms some space to work with i've gone with parallel walls and intend to use acoustic panels to treat the rooms afterwards. I plan to be able to have the ability to record live drums and guitar amps without disturbing my neighbors 15' away!! This is the key issue. Although i don't plan to be recording drums all the time. I'm not that worried about monitoring as i monitor at pretty low levels. I intend to get builders to do the exterior building and i'll frame and do all the inside work. My budget is 50k euros. As Rod says in the book it's a big waste of money if you don't get it right. We're pretty happy with the design at the moment but just a bit unsure whether the soundproofing will be sufficient. I'd love to hear any thoughts or comments on this or any other issue. Two of our key issues at the moment are 1. Is there any real benefit of having an internal isolated floor? 2. We're trying to decide between two Hvac systems.(one for each room) External or internal. I like the idea of internal wall mounted units as this means theres no exterior fan noise that may disturb the neighbors if they want to sit in their garden during the summer. The unit we're looking at http://www.ehs-intl.co.uk/product/viewP ... hp?pid=231 This unit has two 3" or so diameter pipes that can run from it straight through the wall to the exterior. Now i know that this will compromise the soundproofing but which is better. Running the pipe straight out the wall to some kind of baffler box system (which is what my friend did) or running the pipes between the interior an exterior walls to an exit point further away in the building? Thanks I've attached Jpg's of all detailed plans with construction and materials below.

A couple of comments: 1) You seem to have three- and four-leaf walls in there. Is that by design, or are the outer leaves not really two-leaf walls already, for some construction reason? 2) The plan calls for two layers of "9 mm gypsum board" :shock: 9mm is REALLY thin. Is that a mis-print? You should be using 16 mm gypsum board. The resonant frequency, mass and other properties of 9mm drywall are way off from what you need. 3) The plan calls for the inner leaf frame to be "supported by resilient sound isolation clip supports off block wall". :shock: Why do you need resilient clips AND a decoupled frame? And even if yo do need both for some really strange reason, then why put the clips on the BACK of the studs, up against the outer leaf? That makes no sense... 4) same problem on the ceiling: You seem to be suspending your ceiling joists from iso-clips and hat channel, then hanging the drywall from the joists. Why do it backwards? In fact, why do both? Seems like a waste of time and money, for zero gain in isolation, and in fact possibly a LOSS in isolation.... 5) Two-leaf walls and two-leaf windows between rooms, but only single doors???? How are you planning to build those doors to get anywhere near the same isolation as the two-leaf walls and double glazing? Those were the things that caught my attention initially. - Stuart -

Hey Stuart, Thanks for the reply 1) You seem to have three- and four-leaf walls in there. Is that by design, or are the outer leaves not really two-leaf walls already, for some construction reason? AMA; There is an 300mm exterior structural wall (indicated brown on the drawings), constructed in two 100mm leaves of concrete blockwork with a 100mm cavity between with thermal insulation (indicated green on the drawings). The outer blockwork leaves are built as two leaves but are fully connected to each other with stainless steel wall ties throughout, at the foundation base, at wall plate level, and around all openings (this is a standard construction method in this country and fully complies with the local building regulations). Thus not ideal as two separate isolated walls. Our design looks at this wall as one, separate!- then we construct the inner isolated wall (indicated blue on the drawing) - this is made up as follows- Isolation hangers off the exterior block walls in approx 50mm air space, then 100x50mm timber studding to support 2 sheet green glue laminated plasterboard finish with 100mm rockwool insulation between the studs. 2) The plan calls for two layers of "9 mm gypsum board" 9mm is REALLY thin. Is that a mis-print? You should be using 16 mm gypsum board. The resonant frequency, mass and other properties of 9mm drywall are way off from what you need. AMA; 15mm is all Gypsum Industries supply, so it will have to be 15mm. Is the make up of the wall as follows? - 100x50mm timber studding @ 400mm ctrs with two 15mm layer green glue laminated plasterboard (30mm) and skim finish? 3) The plan calls for the inner leaf frame to be "supported by resilient sound isolation clip supports off block wall". Why do you need resilient clips AND a decoupled frame? And even if yo do need both for some really strange reason, then why put the clips on the BACK of the studs, up against the outer leaf? That makes no sense... AMA; I don't really understand this one! Lets try this! - The blockwork cavity wall (brown) is the exterior wall and structural enclosure of the building, the isolation clips are the main fixings to support the decoupled frame internally (blue) off the exterior wall. or Is there some problem with using the timber studding, are you suggesting fixing the plasterboard straight to the isolation clip system? If so what will hold up the acoustical rockwool insulation? or is the acoustical rockwool insulation required? 4) same problem on the ceiling: You seem to be suspending your ceiling joists from iso-clips and hat channel, then hanging the drywall from the joists. Why do it backwards? In fact, why do both? Seems like a waste of time and money, for zero gain in isolation, and in fact possibly a LOSS in isolation.... AMA; Same again- The roof rafters and joists are connected to the roof exterior finish and the exterior walls, thermal insulation is indicated (green) laid between the roof joists- (all would transmit noise to the interior). Then the iso-clips and hat channel are fixed to the roof structure to suspend the decoupled ceiling (blue) or Is there some problem with using the timber studding, are you suggesting fixing the plasterboard straight to the isolation clip system? If so what will hold up the acoustical rockwool insulation? or is the acoustical rockwool insulation required? 5) Two-leaf walls and two-leaf windows between rooms, but only single doors???? How are you planning to build those doors to get anywhere near the same isolation as the two-leaf walls and double glazing? AMA; I agree. The proposal called up for 3 sheet leaded doors and magnetic seals

15mm is all Gypsum Industries supply, so it will have to be 15mm.

15mm is fine.

There is an 300mm exterior structural wall (indicated brown on the drawings), constructed in two 100mm leaves of concrete blockwork with a 100mm cavity between with thermal insulation (indicated green on the drawings).

That's already pretty massive! that alone should be giving you fairly decent isolation.

I don't really understand this one! Lets try this! - The blockwork cavity wall (brown) is the exterior wall and structural enclosure of the building, the isolation clips are the main fixings to support the decoupled frame internally (blue) off the exterior wall.

The question is, why do you need to "support the decoupled frame"? Doing that couples it again, and there is no need to support it anyway. You seem to be missing the point of "room in a room" construction: It is exactly what it says it is. First you build the outer room (four walls plus roof), as a free-standing structure, then you build the inner room (four walls plus ceiling) as another free-standing structure. There is no mechanical link between them. Nothing touches. Not even a single nail. The only thing in common to the rooms is that they both rest on the same floor, but apart form that there is nothing that ties them together, not even iso clips. There is an air gap in between the two structures, on all five sides, and the air gap should be filled with insulation, such as fiberglass or mineral wool, but that's it. No other connection at all. Isolation clips and hat channel are normally used when you don't (or can't) build a true fully decoupled room in a room. You would use those when you already have a stud wall in place and need to isolate it better (not your case). In that case, you would take off the existing drywall from the studs, put the clips and hat channel on the studs, then put the drywall back again, on the hat channel, taking care that no screws contact the studs underneath. But this is not what you are doing. What you are showing in your plans is that you are hanging the studs and joists from the clips, then hanging the drywall from those studs / joists. I'm not even sure that the clips are rated to do that: The are meant to support just the channel and drywall, not the studs and joists as well.

Then the iso-clips and hat channel are fixed to the roof structure to suspend the decoupled ceiling (blue)

But that isn't what your plans show! Your plans show the JOISTS being suspended form the isol clips and hat channel, rather than the other way around! The clips should be attached to the joists then comes the hat channel, then the drywall is attached to the hat channel. In other words, you have the clips and hat channel on the wrong side of the joists. Look at the picture on page one here, to see how to do it right on your ceiling: http://www.rpginc.com/products/cdm/prod ... so-qrc.pdf And look at page five of this report to see how to do it on the walls: http://www.rpginc.com/whitepapers/Drywa ... 0Clips.pdf As you can see, in both cases the clips come AFTER the frame, not before it. The clips hold the channel, which holds the drywall. But since you are building a decoupled frame anyway, they you do NOT need the clips or channel at all! Your wall is already decoupled, since there is no contact between the studs and the outer structure (except at the floor). Using clips and hat channel on a decoupled wall is pointless: it will not gain you anything acoustically, and will just cost you money.

are you suggesting fixing the plasterboard straight to the isolation clip system?

Exactly. That's the correct way to do it, IF you don't have a decoupled wall. In your case you DO have a decoupled wall, so just forget the clips / channel, and save money.

If so what will hold up the acoustical rockwool insulation?

The drywall! For the ceiling, the layer of insulation (just use plain old ordinary 48 kg/m3 mineral wool or fiberglass: don't waste your money on anything "acoustical") will rest directly on the drywall. In the case of the walls, the entire air gap between outer leaf leaf (concrete) and inner leaf (drwyall) will be filled with the same mineral wool. It won't need any additional "holding up" if you install it correctly.

The proposal called up for 3 sheet leaded doors and magnetic seals

How many seals per door? At least three independent seals, I guess, and even then you might not get the same level of isolation. Wouldn't it be cheaper to use two back-to-back solid wood doors with double or triple seals? By the way, your link to the HVAC unit doesn't work. - Stuart -

Stuart Thanks for the very helpful comments, we are currently revising the drawings- Removing the isolation system to the walls n ceiling and constructing the 'inner room' off the floor slab in timber stud. The inner ceiling will be supported off the inner wall studding with no connections to outer structure Removing the Rockwool insulation and using standard insulation. Upgrading the doors to two solid core doors, with plasterboard sheeting, with 3 magnet seals to each, between Live Room and Control Room. Air handling site = http://www.citycool.ie The item is = PMINISW which is the first one on the 'Fixed Unit' page of the site http://www.citycool.ie/docs/PMINISW%202 ... n%202p.pdf Thanks again -AMA-