GARAGE DESIGN USING A MIXTURE OF PLANS

thedeadzeds · Post by **thedeadzeds** » Fri Jan 03, 2014 2:29 am

I should really pay more attention. As much of a hassle it is, I think I will disconnect the 2x4 stud walls from the ceiling and start again. I suppose at least the stud walls are all measured to fit, all I need to do is take a few inches off the height. On the bright side, better that this was discovered before I put any insulation or drywall in hey?

So, what I need to do then is:

1. Take a few inches off the stud walls so none of the timber touches the existing ceiling beams?
2. Attach new ceiling joists to the stud walls. Joists will be interleaved between the current joists but not touching them.
3. Is there a specific joist I should be using for the ceiling i.e 2x6, 2x8 etc? and do they need to be 16 on center, 8 on centre etc
4. As the old joists will be completely filled with rockwool rwa45. How do you prevent the new joists touching the insulation between the exisiting joists or does this not matter?

I'll put a sketchup soon so to ensure I have got this correct

Thanks again Stuart

Soundman2020 · Post by **Soundman2020** » Fri Jan 03, 2014 4:36 am

I should really pay more attention. As much of a hassle it is, I think I will disconnect the 2x4 stud walls from the ceiling and start again. I suppose at least the stud walls are all measured to fit, all I need to do is take a few inches off the height.

Right. But the question is "how much?". You need to figure backwards from the size joists you will need (once again, your structural engineer will tell you what size and what spacing you need), and the size of the gap you want to leave between the existing joists and the new drywall, plus the thickness of your top top plates: That tells you how far you need to cut the studs down.

On the bright side, better that this was discovered before I put any insulation or drywall in hey?

Right! You got lucky: you'd be surprised the number of folks who come here after their build is pretty much finished, only to find out that they need to take most of it down and re-do it correctly... Some do, and up with great results, others don't, and we never hear from them again: I wonder why...

If you have a few minutes, it would be VERY instructive to read over the thread of one of the guys who did it right! http://www.johnlsayers.com/phpBB2/viewt ... =2&t=17363 You can avoid some of the pitfalls that caught him out initially, and that he spent so much time and money to fix.

1. Take a few inches off the stud walls so none of the timber touches the existing ceiling beams?

Right!

2. Attach new ceiling joists to the stud walls. Joists will be interleaved between the current joists but not touching them.

Right! The common issue here is that there already might be things up there that interfere with that plan, such as piping, HVAC ducts, electrical work, cross-bracing, etc. As long as your joist bays are totally free from all of that, then it is dead easy to do the "interleave". Now, before you do the interleave, you also should consider if you have enough mass on the floor above you: If not, you might need to beef that up with more mass, first.

3. Is there a specific joist I should be using for the ceiling i.e 2x6, 2x8 etc? and do they need to be 16 on center, 8 on centre etc

Yep ! The exact joist size you need is the one that your structural engineer prescribes in his report!

You can get a rough idea by looking at span tables, but those are only useful if you understand the concepts of dead load, live load, deflection, and the load carrying ability of the different types of wood that joist are available in, in your area...

4. As the old joists will be completely filled with rockwool rwa45. How do you prevent the new joists touching the insulation between the exisiting joists or does this not matter?

There's no problem with the insulation, as long as it is not jammed in place. Provided that you just place it in normally, so if just fits the gaps without being forced in, then you are fine. Insulation will not flank unless it is compressed a fair amount.

I'll put a sketchup soon so to ensure I have got this correct

Perfect!

- Stuart -

thedeadzeds · Post by **thedeadzeds** » Fri Jan 03, 2014 5:35 am

Thanks Stuart

so am I correct in saying this is what yo mean by interleave the new joists. Apologies for the rubbish sketch

ceiling mine.png

I've found this but it looks as if the insulation is weaved between the both joists so not sure if this is correct?

indi ceiling.png

Would it be ok to use 50mm insulation between the existing joists and 100mm between the new ones?

thanks

Soundman2020 · Post by **Soundman2020** » Fri Jan 03, 2014 5:48 am

so am I correct in saying this is what yo mean by interleave the new joists.

Perfect!

I've found this but it looks as if the insulation is weaved between the both joists so not sure if this is correct?

Your suspicions are well founded: not so correct. You COULD do it that way: it will still work but your way is better.

- Stuart -

thedeadzeds · Post by **thedeadzeds** » Fri Jan 03, 2014 6:01 am

awesome.

Last question hopefully. Would it be ok to use 50mm of RWA45 between the existing joists and 100mm between the new ones? Or do i need to use the same mil for both

Soundman2020 · Post by **Soundman2020** » Fri Jan 03, 2014 6:57 am

Put in as much as you can, on both sides. More is better here. You could even consider putting additional insulation in the vertical spaces between the existing joist and the new ones, to fill as much of the gap as possible. The only thing to watch out for is to not compress it much. Compressing it by 10% or so won't do any harm, but compressing it 50% probably will!

But do try to fill as much of the gap as you can, and as much as your local building code allows. The purpose of the insulation is to damp the internal resonances going on inside the cavity, and also to change the way the air behaves as sound moves through it. In effect, by filling the cavity entirely, to sound waves it appears to be 1.4 times BIGGER than it was empty... yup... this whole acoustics thing is not intuitive! Who would have thought that by filling up a gap you make it bigger, not smaller? Sort of like Dr. Who's Tardis (if you happen to be a fan of that series): "It's bigger on the inside!". Yup.

- Stuart -

thedeadzeds · Post by **thedeadzeds** » Thu Jan 16, 2014 6:06 am

Sorry about another email but I just want to check everything before i go any further. I have now taken the stud walls down, ready to be cut in so i can place a separate ceiling on the studs as discussed earlier. The inner frame will not touch anything. My engineer has advised on 2x7's for the new ceiling 16 oc which he said will hold 2 layers of 15mm plasterboard no problem. Ive added a few more sketchups to address some more issues.
Oh, the joys of ventilation. Like most people, Im struggling with this. I believe I need two baffle boxes with fans. One to bring fresh air in and one to take the air out. Please see diagram baffle boxes. If I'm correct, the air will be taken directly from outside into the internal room, and air taken from the internal room to the outside. I understand that this will ventilate the inner room.
Questions:
1. Do I need to ventilate the void (air gap) between the inner and outerleaf? I'm not sure if i need to drill holes into the brick and cover with normal vents in order for air to circulate this area. Please see diagrams outerleaf ventilation 1 and 2. It seems important to have some sort of air moving around this void (air gap) but it also seems silly to have holes or gaps in the brick work which sound could easily pass though. Or do I just completely seal the outerleaf and hope it will vent itself with the air available to it. This is really confusing me.
2. If I do need to ventilate the air gap (void), can the baffle boxes be placed as per diagram – see diagram “BAFFLE PLACEMENT 1” so there air is taken from inside the garage. Or do I need to just go with “BAFFLE PLACEMENT 2”
You will also see from previous sketches that there is a current vocal booth already build within the garage. This does not touch any of the walls or ceiling but will be attached to the new frame. You can see from the diagram that there is a area all the way around the vocal booth which I intend to use for small storage. I can walk around this section so its about 2 feet gap all the way around.
3. For access to this area, do i need to build 2 doors as per diagram “doors” or will one suffice. Not sure if building 2 doors will then create a tripple leaf.
4. Can you have a look at my baffle boxes? I’ve seen many on this site which are in the ceiling but I will need to have mine in the walls as there is no room above. I have yet to find any that go through a brick wall so I need to check:
• The placement of the baffle – do I place this directly through both walls and attached it to the brick wall? See Baffle 1. This way seems to re-couple the inner and outerleaf which is obviously bad. Or is Baffle 2 better? Or are both of these rubbish?
• Is any of these fans the correct sort of thing? Please see links

http://www.amazon.co.uk/Manrose-100mm-S ... roduct_top

http://www.ebay.co.uk/itm/HYDROPONICS-6 ... 4173ea876b

http://www.charlieshydro.co.uk/store/Ve ... n-396.html

http://www.justfans.co.uk/silent-acoust ... p-197.html

and is the placement of the fan correct and can this be used for both intake and out take? I’m assuming I can just turn the fan to suit the air direction?
• I intend to use this ducting. Is this correct?

http://www.ebay.co.uk/itm/FLEXIBLE-ACOU ... 3cd1e96ce6

• Lastly, the vocal booth will is currently ventilated so I do not need to run any air in there (using a very basic design, but does the job very well).
Many thanks
Craig

doors.jpg

BAFFLE 1.png

BAFFLE 2.png

BAFFLE PLACEMENT 1.png

BAFFLE PLACEMENT 2.png

Soundman2020 · Post by **Soundman2020** » Fri Jan 17, 2014 8:44 am

My eyes are aching from all those neon-bright colors!!!

Can I suggest that you download SketchUp and use that for your studio design? It's free, is fairly easy to use, and is a very powerful, useful tool for designing studios. (And the colors don't zap your eyes!

)

My engineer has advised on 2x7's for the new ceiling 16 oc which he said will hold 2 layers of 15mm plasterboard no problem. Ive added a few more sketchups to address some more issues.

2x7's? That's an unusual size: I didn't even know you could get such a dimension. Joists normally come in 2x6, 2x8, 2x10, 2x12 etc. Is that a special order, or can you get that anywhere in the UK? I wish I could get that here: it would save on waste from trimming down larger sizes...

Oh, the joys of ventilation. Like most people, Im struggling with this.

Here's some encouragement for you: the more you learn about HVAC, the WORSE it gets! Each tom you think you are finally getting somewhere, and you can see light at the end of the duct... errr .. I mean tunnel, you look up one more minor little reference and find yourself blown all the way back at square one, with a whole new bunch of stuff that you have to learn and never even knew existed!

I believe I need two baffle boxes with fans. One to bring fresh air in and one to take the air out.

You can probably get by with just one fan: When the door is closed, the room basically becomes an air-tight sealed system except for the HVAC ducts, so placing one fan at any point will force air through the entire system. I usually put the fan on the exhaust box, outside the outer leaf, so it is sucking air through the system. But you could also put it on the supply box, outside the outer leaf, blowing air in. The most important point is to size the ducts and silencers correctly for the volume and speed of air that you need to move, estimate the static pressure of the system, then find a fan that is able to move the right amount of air for that static pressure.

Also, for high levels of isolation, you probably need a silencer on EACH leaf for EACH vent: In other words, one box on the outer leaf and another on the inner leaf for the supply vent, and ditto for the exhaust vent.

the air will be taken directly from outside into the internal room, and air taken from the internal room to the outside.

Right.

1. Do I need to ventilate the void (air gap) between the inner and outerleaf?

No. That is a "dead" space between the two leaves. Since both of the leaves are sealed absolutely airtight, there's no need to ventilate it. That said, there still might be a need to install a vapor barrier: consult your local building code on that.

I'm not sure if i need to drill holes into the brick and cover with normal vents in order for air to circulate this area.

That would destroy your air-tight seal on the outer leaf, and therefore would destroy your isolation.

It seems important to have some sort of air moving around this void (air gap)

Why? It's an empty space, sealed off from both the outside world and from the studio interior. It is no (conceptually) from a typical stud wall with drywall on each side. You don't need to drill holes in that to ventilate it, so why would you need to drill holes in an MSM wall?

Or do I just completely seal the outerleaf and hope it will vent itself with the air available to it.

You seal BOTH leaves hermetically, not just the outer leaf. Airtight seals are critical to isolation, and both leaves must be absolutely air-tight, not even a tiny crack or pinhole anywhere.

2. If I do need to ventilate the air gap (void), can the baffle boxes be placed as per diagram – see diagram “BAFFLE PLACEMENT 1” so there air is taken from inside the garage. Or do I need to just go with “BAFFLE PLACEMENT 2”

You don't and cannot ventilate the air gap, so neither of those diagrams is correct. Assuming you need high levels of isolation, you would put one silencer box inside the inner-leaf, another silencer box outside the outer-leaf, cut the holes for the ducts, and couple them across the gap with a flexible coupler, NOT a solid coupler: There can be no solid connections across that gap at all: not a single nail, screw, wire or duct. Everything must be resilient, flexible, and calculated carefully to not cause any flanking between the two leaves. If you do not need such a high level of isolation then you can probably get by with just one silencer box per duct, in which case it can go either inside the inner-leaf or outside the outer-leaf, whichever works out better, but you still need the flexible coupling across the gap.

there is a current vocal booth already build within the garage. This does not touch any of the walls or ceiling but will be attached to the new frame. You can see from the diagram that there is a area all the way around the vocal booth which I intend to use for small storage.

So that booth is not going to be decoupled from the inner leaf? That's fine, as long as it is not connected to the outer leaf anywhere, provided that you understand that it will not have much isolation from the room. If it is just for storage, that's fine, but it would not be very useful as an isolation booth.

I can walk around this section so its about 2 feet gap all the way around.

Seems like a lot of wasted space! There must be some way you could put that to better use?

3. For access to this area, do i need to build 2 doors as per diagram “doors” or will one suffice.

One door is fine, since it is part of the inner-leaf and therefore not isolated from the room. The only real purpose of that door is aesthetics: to hide the stuff you are storing.

4. Can you have a look at my baffle boxes? I’ve seen many on this site which are in the ceiling but I will need to have mine in the walls as there is no room above. I have yet to find any that go through a brick wall so I need to check:

Is the fan I am using the correct sort of thing? Please see link

Hard to say, since it doesn't even give the most basic data that you need to know!!!! Such as how much air it can move (normally measured in cubic feet per minute), and what static pressure it can operate at (measured in inches of water) while moving that much air.

You can't guess here: you need to do the math. You need to figure out your room volume, how many room changes per hour you need, what that works out to in air volume (how many cubic feet per minute do you need to move through the room), what size duct you need to move that amount of air at the correct speed (slower than 300 feet per minute), how long your total duct length will be (including silencer boxes), what static pressure that length of duct will present to the fan, and based on all of that you can then find the right fan that can move the amount of air you need against the static pressure you will have. It is REALLY important to get this math right!

and is the placement of the fan correct and can this be used for both intake and out take? I’m assuming I can just turn the fan to suit the air direction?

What you show is an in-line fan, that is placed in the middle of a duct someplace. That's fine, but don't forget that you will need access to that fan, in case it needs cleaning, repairing or replacing, so you cannot have it inside your wall! Also, if it is inside the wall, or placed in line BEFORE the silencer, then you will hear fan noise coming back down the duct. It might be better to use a fan on the far end of the exhaust duct, on the other side of the silencer.

• I intend to use this ducting. Is this correct?

Perhaps, perhaps not. You HAVE to do the math to figure it out. And flex duct will NEVER give you the nominal flow in the real-world, since it is practically impossible to install it such that the full interior diameter is maintained throughout the entire length: You normally need to go up at least one size, and often two sizes, to get it right. So if you calculations say that you need 6" duct, for example, then you should use at least 8" duct, and even better would be 10" duct. Flex duct is not to be trusted, unlike rigid duct.

Lastly, the vocal booth will is currently ventilated so I do not need to run any air in there (using a very basic design, but does the job very well).

How is it ventilated? That is very likely an issue here. Whatever you are using to ventilate it right now must, by definition, cross over the air gap between your new inner-leaf and the outer leaf. So that will need to be fixed too: if it is rigid, it will need to be decoupled, and if it does not already have silencers on it, then it will need silencers, just like the ventilation for the new room.

- Stuart -

thedeadzeds · Post by **thedeadzeds** » Sat Jan 18, 2014 10:52 pm

Thanks again Stuart

2x7's? That's an unusual size: I didn't even know you could get such a dimension. Joists normally come in 2x6, 2x8, 2x10, 2x12 etc. Is that a special order, or can you get that anywhere in the UK? I wish I could get that here: it would save on waste from trimming down larger sizes...

Yes, 2x5, 2x7 and 2x9 are standard in the UK as well as 2x4, 2x6, 2x8

Seems like a lot of wasted space! There must be some way you could put that to better use?

Its mainly due to cost, i simply cannot afford to soundproof the whole garage and as its only for personal use, I dont really need it any bigger

Thanks for the links to the baffles, awesome

I've just noticed an issues with the current vocal booth. I presumed it was only touching the concrete slab and nothing else. However, the roof of this is pitched and one section of it is slightly touching the existing garage joists.

1. Is this a major concern? If yes, would It be better for me to Essentially, use the vocal booth as a stand alone stud wall as per new sketchups?

2. So the vocal booth and stud walls attached to them become the outer leaf and the inner leaf remains completely decoupled from it?

3. If this is the way to do it, how would the stud walls walls attached to the vocal booth need to be constructed? would it be as per diagram "walls" and

4. Is the vapor barrier in the correct place?

5. Also, does the joists section above the vocal booth need to be filled with rock wool? See diagram new walls 2 the area highlighted in red?

thanks

thedeadzeds · Post by **thedeadzeds** » Wed Jan 22, 2014 7:45 pm

Really sorry to bump so early but I was hoping to order my timber for the weekend?
Apoligies

thedeadzeds · Post by **thedeadzeds** » Tue Jan 28, 2014 6:23 am

Soundman2020 · Post by **Soundman2020** » Thu Jan 30, 2014 1:08 pm

There seems to be problem with many of your images: they are not showing up properly. Maybe you could edit your post to fix that, as it's hard to see what you are explaining in the text.

The roof of this is pitched and one section of it is slightly touching the existing garage joists.

1. Is this a major concern? If yes, would It be better for me to Essentially, use the vocal booth as a stand alone stud wall as per new sketchups?

Yes, that is a problem! Even one single nail or screw bridging across the gap is plenty good enough to destroy your isolation.

2. So the vocal booth and stud walls attached to them become the outer leaf and the inner leaf remains completely decoupled from it?

Right. That makes sense.

3. If this is the way to do it, how would the stud walls walls attached to the vocal booth need to be constructed? would it be as per diagram "walls" and

You would just build a frame across there that does NOT touch the booth at all, and then you'd need two doors: one on the new frame, and one on the vocal booth.

4. Is the vapor barrier in the correct place?

Not sure: you'd have to check your local building code to find out. It depends on the climate, and should usually go on the side of the wall cavity that is warmer in winter.

5. Also, does the joists section above the vocal booth need to be filled with rock wool? See diagram new walls 2 the area highlighted in red?

I can't see which part is "highlighted in red", since your images are not showing up, but yes you do need insulation in all the cavities between leaves.

- Stuart -

thedeadzeds · Post by **thedeadzeds** » Thu Jan 30, 2014 7:06 pm

Hi Stuart,

That's really strange as I can see them fine on my laptop. I've amended them now so hopefully you can view the diagrams

thanks
Craig

thedeadzeds · Post by **thedeadzeds** » Wed Apr 23, 2014 9:50 pm

Hi Guys,

Just a quick question regarding the vapour barrier. To save you looking through the old posts, this should give you an update.

Single detached brick garage 16 foot by 8 foot. Only ¾ of the garage will form the studio. Stud walls are now up which are 2 inches form the walls, new ceiling joists are inter leaved between the existing joists so the frame is completely decoupled from the existing structure (which the exception of the concrete floor). Stud walls have now been filled with 100mm Rockwool. Baffle boxes not yet installed but they will be once the plasterboard is up. The insulation has been up now for about 2 weeks as I have not yet had chance to put the vapour barrier up. The Rockwool on the ceiling has started to gather condensation. I have had the door open as much as possible to get some air moving in there but its not doing much.

Question 1 – can I continue to install the vapour barrier over the Rockwool whilst the condensation is still there or do I need to figure out how to completely dry it first?

Question 2 – building regs have not actually specified a specific vapour barrier, they said I just need one. Can anyone recommend one. I’m based in the UK.

Thanks

Soundman2020 · Post by **Soundman2020** » Mon May 12, 2014 9:26 am

Question 1 – can I continue to install the vapour barrier over the Rockwool whilst the condensation is still there or do I need to figure out how to completely dry it first?

Get rid of the condensation first, for sure! Yes, in theory it could leave through the walls over time, but it's impossible to say how long that "time" would be, and you certainly do not want to trap high humidity inside your walls. So get a good dehumidifier going in there full-time and keep the door closed until the humidity is under control, the condensation is gone, and the insulation is totally dry: Then put up your vapor barrier.

Question 2 – building regs have not actually specified a specific vapour barrier, they said I just need one. Can anyone recommend one. I’m based in the UK.

Check with local builders in your area to find out what they use, and how they install it. Normally, 6 mil polyethylene stabled to the studs just before you put the drywall on is fine, but check to make sure that is OK and legally acceptable where you live.

One other thing: try to figure out for sure if it really is only condensation that you are dealing, and not something worse... Hopefully you don't have water infiltrating through the walls... You need to be 100% certain of that before you seal it up.

- Stuart -

John Sayers' Recording Studio Design Forum Archive

GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS

Re: GARAGE DESIGN USING A MIXTURE OF PLANS