Studio build in Wales, UK...again!

Gregwor wrote:

Let me know the next step and info you need in order to help you help me!

I think you've nailed everything on the head with your plan. Go into SketchUp and draw up some silencers with the correct interior cross sectional areas and you're off to the races! Greg

Ok great, so I assume I can just input some new numbers in to the equations you gave me in your previous reply? If so then I have some questions: What is the X dimension? The depth? Why do I need to minus 7 before dividing it by the width? Then why do I need to add 11.5 to the length? Probably obvious, but I don't understand it yet. Thanks, Paul

What is the X dimension? The depth? Why do I need to minus 7 before dividing it by the width? Then why do I need to add 11.5 to the length?

Sorry, I thought I had posted this picture on your thread already: The equations I used are just based off of this picture. I figured out the simple equations just to speed up the design process. I hope it all makes sense now! Greg

Gregwor wrote:

What is the X dimension? The depth? Why do I need to minus 7 before dividing it by the width? Then why do I need to add 11.5 to the length?

Sorry, I thought I had posted this picture on your thread already:

Not preserved: Gregwor's Silencer Box.png

The equations I used are just based off of this picture. I figured out the simple equations just to speed up the design process. I hope it all makes sense now! Greg

Hi Greg, Okay now that I see your diagram that makes a lot more sense, that's brilliant! So, focusing on just the inlet silencer for now, I've input some figures in to the formulas you gave me and here's what I've come up with: Width = 24” X = 8.5” Length = 45.5” Outer Depth = 24” Inner Depth = 20” CSA = 1.1805 sq. ft Velocity = 130.859 ft/min Radius = 85 sq. in Duct size = 10.4” Does that sound right? This would mean my boxes would be roughly L4' x W2' x D2', which means I could utilise the standard 4'x4' MDF sheets very easily. The boxes will be supported on top of my rear wall treatment framing, which will be more or less free standing, so providing I make it beefy it should easily be able to accommodate such a box on top. Regarding the duct size of 10.4", this is the size of the hole I need going into the box from the flex duct joining to the corresponding box on the other leaf correct? Is it also the size of the hole which would usually lead to the register? (I will just cut a hole for the air to come out of which will pour out over my mini split) Now I need to repeat this process for my outlet silencer box which I would like to be a Y configuration; if I keep the volume of the box the same but re-juggle the dimensions so that I can make it fit where I want it, will that work for a Y configuration? There would be two holes leading to the exit hole, which would feed into the corresponding box for the outer leaf, which would be connected to the fan. Would the hole size of 10.4" be the same for all 3 holes? Paul

Radius = 85 sq. in Duct size = 10.4” Does that sound right?

Everything up to here makes sense and looks good to me! For your duct work feeding your boxes (from out size your room of course) can be estimated using this chart:

If I worked out using the 30% minium fresh for my room volume with 6 air changes per hour then it would be: 23.92 x 19.57 x 11 x 6 = 30,895.55 30,895.55 / 60 = 514.93 30% of 514.93 = 154.48cfm

Using this info along with the sizing picture above, we can see that a 7" round duct would be great. We can see that the CSA of the 7" round duct is 38.38 sq inches. If the CSA of the silencer box is 170 sq inches, that means we have a CSA ratio of 4.43! That is great!

This would mean my boxes would be roughly L4' x W2' x D2', which means I could utilise the standard 4'x4' MDF sheets very easily.

:thu:

The boxes will be supported on top of my rear wall treatment framing, which will be more or less free standing, so providing I make it beefy it should easily be able to accommodate such a box on top.

Something to investigate is how much weight you're able to put on the floor itself. These boxes and your framing are not going to be light!

Regarding the duct size of 10.4", this is the size of the hole I need going into the box from the flex duct joining to the corresponding box on the other leaf correct?

You can see above that you could drive the box with a 7" round feed. This can also be the size of duct going between the inner and outer leaf silencer boxes. If you want to use flex duct to join the two that might be hard to find 7" flex duct in your area. If so, you can use a flexible membrane to join the 2 steel ducts (or if your boxes are very close together you could just frame square sleeves (ex: 10"x4" or 8"x6") and use the membrane to join the two. If you can't find 7" anywhere, you could always use 8". You just won't have as great of CSA ratio.

Is it also the size of the hole which would usually lead to the register? (I will just cut a hole for the air to come out of which will pour out over my mini split)

The size of hole that is inside of your room is where your air velocity determines the size. You must keep it under 300 ft per min. It looks like you're at 130.859 ft/min so as long as your hole is the same size as your box CSA you are going to have a very nice slow air velocity!

Now I need to repeat this process for my outlet silencer box which I would like to be a Y configuration; if I keep the volume of the box the same but re-juggle the dimensions so that I can make it fit where I want it, will that work for a Y configuration?

If you don't get the exact CSA that's fine. I recommend just making it as big as you can (within reason of course). Keeping a friendly 4' for material reasons is awesome but not always possible. The Y configuration uses the same principles.

There would be two holes leading to the exit hole, which would feed into the corresponding box for the outer leaf, which would be connected to the fan. Would the hole size of 10.4" be the same for all 3 holes?

Without seeing a rough sketch I'm not understanding what you mean when you say that 2 holes will feed an outer leaf box? If your inner leaf box has to Y, I would make it so that the two holes of the box feed your room, not be used to connect to your outer leaf box. Maybe I'm just not understanding your design here. Greg

Gregwor wrote:

Radius = 85 sq. in Duct size = 10.4” Does that sound right?

Everything up to here makes sense and looks good to me! For your duct work feeding your boxes (from out size your room of course) can be estimated using this chart:

Not preserved: Feed Duct Size.png

Greg

Hey that's great Greg, so I will get on and design some boxes now, thanks for all your help so far. Here's a quick sketch of how I'm thinking to design the inlet box. I have some questions about the location of the in and out holes for each silencer: Is there a best practice when it comes to positioning these holes? e.g. should they be offset from each other? Is it okay if they are opposite each other (one on each end) with the baffles in between or should one be on the side and one on the front? Paul

Here's a quick sketch of how I'm thinking to design the inlet box.

Tip from experience: design it such that the lid just sits on top to close up the box. Trying to get a nice perfectly rectangular lid to slip into the box is difficult.

Is there a best practice when it comes to positioning these holes? e.g. should they be offset from each other? Is it okay if they are opposite each other (one on each end) with the baffles in between or should one be on the side and one on the front?

I've read that it is recommended to have the inlet and outlet be on a different axis than one another. Like everything in the studio design world, there will be limitations to what you can do so if you have to have it the way you drew this one up, so be it. Just make sure that the inlet and outlet are far enough over that the baffle blocks any sound from blowing through the duct liner and out the hole without having to make the extra few turns. Greg

Gregwor wrote:

Here's a quick sketch of how I'm thinking to design the inlet box.

Tip from experience: design it such that the lid just sits on top to close up the box. Trying to get a nice perfectly rectangular lid to slip into the box is difficult.

Is there a best practice when it comes to positioning these holes? e.g. should they be offset from each other? Is it okay if they are opposite each other (one on each end) with the baffles in between or should one be on the side and one on the front?

I've read that it is recommended to have the inlet and outlet be on a different axis than one another. Like everything in the studio design world, there will be limitations to what you can do so if you have to have it the way you drew this one up, so be it. Just make sure that the inlet and outlet are far enough over that the baffle blocks any sound from blowing through the duct liner and out the hole without having to make the extra few turns. Greg

Thanks Greg. So that is actually how I've designed it, the lid will sit on top, the lip you can see is just so the duct liner on the lid slots in place. I realise now that the baffles should also extend to the top - doh! I'll try to come up with a way to have the holes on different axis, the box could even be an L shape if needs be I suppose? Paul

I'll try to come up with a way to have the holes on different axis, the box could even be an L shape if needs be I suppose?

For sure! Check out this weird shaped one I designed for my studio: Note: There are two pictures on this post so you'll have to scroll down to the second picture. Snail Style Silencer Box Design Greg

Hi guys, I finally got round to attempting to upload some older pictures from a few months ago to fill in the gaps in my build diary, hopefully this time they'll upload although it seems I have uploaded them in reverse order, so start from the bottom and work your way to the top if you'd like to see them in chronological order. Let me know if you have any questions or spot anything concerning! Since these pictures quite a lot has been done, I've built some ceiling soffit bass traps, all the walls and ceiling have been insulated as part of the first stage of treatment, and I've finished all the ceiling acoustic hangers, I'll upload the pics asap. Paul

Another picture update, this one is all about ceiling hangers. I still need to upload the pics for the ceiling soffits, windows and insulating, I'll probably get round to that a little later today.

That looks awesome!!!!! Greg

Here's some pics of the ceiling soffits I built. They're full of light fluffy for bass trapping and will be covered with fabric and some down lights will be installed. They're about 2' wide and 1' 6 high at the front and about 1' at the back.

Gregwor wrote:

That looks awesome!!!!! Greg

Thank-you Greg, it's nice to hear!

And here's the pics of the rough framing for the windows. Theres 3 windows at the front of the control room. The frames here are for the cutouts while the glass itself will be in the speaker soffit and side wing framing, forming my RFZ. The main central window will look into the large tracking room, the front left window will look into a smaller booth and the the front right will look out into nature.

Hi guys, Has anyone got any tips for ray tracing 2 angles at once? I'm trying to use sketch up to ray trace reflections from monitors to some windows on side walls which are angled both horizontally and vertically, not only is it time consuming but also very confusing... Any help appreciated! Paul

I've found this useful: Create the surface upright (not angled) and save it as a component, then rotate it with the rotation tool. Then when you edit the component the axes are set to the local space instead of world space. So exit your component, draw a line from your monitors to the face of your window. Now edit the window component and draw a short line from the intersection point on the surface straight forwards (the surface normal), it will be one of the local axes. Now exit the component. Using the protractor tool, click on the intersection point on the surface, set it to measure from the surface normal line, measure the angle to the monitor line but don't click, just look at the angle at the bottom of the window and remember it, then measure the opposite direction and type the figure you remembered, click to set a guide. Now draw your reflection along the guide. I've written this from bed, without a pc, so I may have missed some steps, but have a go! :D Dan

Waka wrote:

I've found this useful: Create the surface upright (not angled) and save it as a component, then rotate it with the rotation tool. Then when you edit the component the axes are set to the local space instead of world space. So exit your component, draw a line from your monitors to the face of your window. Now edit the window component and draw a short line from the intersection point on the surface straight forwards (the surface normal), it will be one of the local axes. Now exit the component. Using the protractor tool, click on the intersection point on the surface, set it to measure from the surface normal line, measure the angle to the monitor line but don't click, just look at the angle at the bottom of the window and remember it, then measure the opposite direction and type the figure you remembered, click to set a guide. Now draw your reflection along the guide. I've written this from bed, without a pc, so I may have missed some steps, but have a go! :D Dan

Thanks Dan, I'll try that out! Paul

If I get time, I'll try to make a quick video of how I do it. It is fast and pretty easy if I remember correctly! Greg

Gregwor wrote:

If I get time, I'll try to make a quick video of how I do it. It is fast and pretty easy if I remember correctly! Greg

Thanks Greg, that would be amazingly helpful

Guys, I am having a bit of a stressful time right now after discovering what I thought was a leak in the roof! :cry: Sorry for the long read, but please read it all if you dare so that you can offer me some advice. The white residue in the photos is actually where the water has mixed with the caulk and dripped all over the place. But, the plot thickens... 1. Where this supposed leak was found the framing and roof deck behind the insulation is wet and there is black mould on the surface. The insulation is obviously wet as well. 2. Now, in other places all the way along the ceiling there is what looks to be condensation on the inner face of the insulation, but behind it both the insulation and roof deck is bone dry. So... what is happening here? Have a look at the diagram I've attached of my roof/ceiling construction. Remember, this is the INNER INSIDE OUT leaf of the control room and I am building the outer leaf around this at a later stage. Therefore there are NO VENTS in the ridge or the soffits as this is my inner leaf. Now, the leak if there was one I am not too worried about as I can easily fix it. I am more concerned with the presence of condensation... If all of this damage was caused by condensation and there actually in fact was never a leak from the outside, then where the hell is all of that moisture coming from??? It cannot be from my breath/sweat as I am not in there enough to warrant this happening, and even if it was the door is always wide open while I am working in there. My theory is either it must be coming from the outside air, or the concrete slab that is still drying out??? It was really cold up until recently, it's only been the last week or so where we've had fairly hot weather.... Perhaps the moisture is rising up to the ceiling during the colder nights, and then in the day time when the sun is on the roof it's heating it up and then the moisture is trying to fall down into the room again??? One thing I know for sure is that there was no condensation or moisture anywhere before I installed all of the insulation and the hangers. I triple checked it and left it for a good few weeks of rain before installing insulation just to be sure. Now with all of that insulation butted up against the roof deck and the hangers beneath it is just acting like a sponge on the inner surface. It is mainly condensing on the face of the insulation which is directly BEHIND the hangers (in the peak of the ceiling). Of course, if I had already built the outer leaf with my roof on top of it then either I would have a vented "third" leaf, or I would just make it a warm roof which does away with the need to have vents. As I cannot currently do that what do you think I should do??? Right now I have just opened both doors and will get a fan in there to dry it all out the best I can, but I do not think it will be a permanent fix... If I had my silencer boxes and ventilation system installed in there do you think this will irradicate the problem??? What I am trying to understand is how other people who have inside out ceilings (presumably sealed airtight like mine) with insulation in the bays do not also have this problem? Is it because they have an insulated cavity behind their ceiling with an outer leaf and roof etc? And because I only have the one leaf which is dividing the inner room with the outside world it is causing a problem? Thanks for taking the time to read and any advice would be much appreciated

Hi Paulus, it most definitely looks like a condensation problem. When you added all that insulation you significantly increased the thermal performance in your roof. The problem you have is the air stays warm up until it meets the OSB roof deck, then it rests against it (if there is a vapour barrier) or begins to absorb. As it does this the cold roof deck cools the vapour, and it condenses... All over the roof. The confusing thing is you say the roof deck is dry. That is probably just gravity drawing the water through the insulation and leaving it on the lower surface of the insulation. Having a completely sealed room like this allows a surprising amount of water vapour to remain in the room. I would think a ventilation system would help it, but really you need your AC in there as soon as you can. If you add silencer boxes and just have passive ventilation it will help alot. I don't think the concrete drying is the problem. How long has it been laid? When you get your second (outer) leaf on and a vapour barrier between the two, against your inner osb3, it will significantly help. How did you water proof your roof deck, on the other hand though? Dan

Waka wrote:

Hi Paulus, it most definitely looks like a condensation problem. When you added all that insulation you significantly increased the thermal performance in your roof. The problem you have is the air stays warm up until it meets the OSB roof deck, then it rests against it (if there is a vapour barrier) or begins to absorb. As it does this the cold roof deck cools the vapour, and it condenses... All over the roof. The confusing thing is you say the roof deck is dry. That is probably just gravity drawing the water through the insulation and leaving it on the lower surface of the insulation. Having a completely sealed room like this allows a surprising amount of water vapour to remain in the room. I would think a ventilation system would help it, but really you need your AC in there as soon as you can. If you add silencer boxes and just have passive ventilation it will help alot. I don't think the concrete drying is the problem. How long has it been laid? When you get your second (outer) leaf on and a vapour barrier between the two, against your inner osb3, it will significantly help. How did you water proof your roof deck, on the other hand though? Dan

Thanks Dan... The weird thing is where I thought I found a leak it is soaking wet behind and in front of the insulation, that is only one section in the middle of the ceiling. The rest of it is bone dry behind the insulation. I left the door open last night and when I came back this morning the condensation on the face of the insulation had got better since yesterday, so it seems like having at least the door open is helping it to dry out. I water proofed the roof deck with roofing felt, that's it. There is no vapour barrier. The slab has been laid about 6 months and I've just finished putting the laminate floor down over underlay on top of it. If I have AC in there then yes, it will keep the air cooler, and if I have ventilation it will pull some of the moisture out via the inline fan, however without the outer leaf, will that be enough to stop the condensation? Paul

The

Paulus87 wrote:

The weird thing is where I thought I found a leak it is soaking wet behind and in front of the insulation, that is only one section in the middle of the ceiling. The rest of it is bone dry behind the insulation.

It's very possible you had a leak. But is that area right at the apex though? If so, it might be the condensation just "pooling" there.

Paulus87 wrote:

I water proofed the roof deck with roofing felt, that's it. There is no vapour barrier.

I assume you have some seams? It might be worth getting up there to check them all.

Paulus87 wrote:

If I have AC in there then yes, it will keep the air cooler, and if I have ventilation it will pull some of the moisture out via the inline fan, however without the outer leaf, will that be enough to stop the condensation?

I would think so, because it will always be on when you're in the room, and when you're not in the room the vents will add passive ventilation. I can't say for sure though. As you may know, cavity walls were designed to prevent condensation. So a single skin (leaf) wall is always on the back foot really. Dan

As an alternative temporary measure, you could add exterior thermal insulation to your roof deck (celotex or something similar) and put felt on top of that. So you would have a warm roof then. As your roof is almost always the biggest problem, this might be good enough in the mean time. Then when you build your outer leaf, just move the celotex to the outer roof deck. If you do this, follow the correct warm-roof design for your area (not sure about wales building regs). You will probably need to replace your felt with a vapour control layer. Dan

Paul, Hopefully you do not have a roof leak. :shock: In my studio build back in 07 it was very airtight. By the time I had put new lumber (wet), drywall and mud and paint. I ran a dehumidifier for a couple weeks and took out 20 gallons of water. If I would have known this before hand I would have stated drying out earlier. I ran into a problem with moisture building up between the panes of glass. That is when I knew I had a problem. Typical construction usually does a dry out period before and after drywall. Like you have found out, just by leaving the doors open, it is helping. If you can, run heat/propane and fans to help remove the moisture. Hopefully it is that simple and like I said hopefully not a roofing problem. Best T