John Sayers' Recording Studio Design Forum Archive

In theory, both leaves should be sealed.

- Stuart -

One point I noticed: It looks like you didn't see my previous post on how to stagger the drywall joint between wall and ceiling.

You have it wrong, like this: It should be like this: Minor but important point...

Also, you must leave gaps in there, for the backer rod and caulk.


- Stuart -

OK, looking at your photos, I'd say that you don't have a lot of choice here: your roof will have to be 3-leaf. There's no easy way you can seal that corrugated zinc nor add mass to it, so if that were my roof, I'd just accept that it has to be 3-leaf, and put some extra mass and distance between the other two leaves to compensate.

Did you architect say how much weight the EXISTING truss can support? For example, can you go with 3 layers of 5/8 up there, plus some thick insulation above it? To me, it doesn't look like that is feasible, but the structural guy can tell you for sure. Hopefully, you can get at least two layers of 5/8" up there, plus insulation!

If you can't get 3 layers on that "middle" leaf, then plan to increase your air gap between the middle and inner leaf, and put an extra layer of drywall on the inner leaf (might require beefing up that 4x8 beam a bit more... check with your engineer). And don't forget that if you put 3 layers on the inner-leaf ceiling, you also need it on the walls if you want to retain good isolation.

Same for the middle leaf: if you put 2 or 3 layers on that, then you also need the equivalent surface density on the walls, so you'll need to beef those up from the inside (between the studs) to the same level. The concept is that each complete leaf has the same surface density all around.

Which leads us to doors and windows: Same rule applies: you have to keep the surface density of the walls for the windows and doors too, and you need multiple seals on them, for the same reason. So for example, if you have 3 layers of 5/8 on a leaf, then you need at least 3/4" laminate glass on that layer, and theoretically it should be 9/10" If the wall is 2 x 5/8" drywall, then you need at least 1/2" laminate glass (theoretically 5/8). In both cases, make the air gap BIGGER than for the wall, since you won't have the benefit of insulation in between! In other words, the frame should stick out of the wall by an inch or two on each side, to allow more depth between the two layers of glass. Theoretically, the path should be about 1.4 times longer if there is no insulation, so if you have 6" air gap on your walls, then you should aim for 8 1/2" air gap for the windows.

Same rule for doors: must be at least the same surface density as the wall, and increase air gap if you can't put insulation in there.

I noticed on your images that you have a window from the studio into the BATHROOM??? Uuuuuhhh Is that necessary?

Also: Don't see your HVAC plan yet! That's a biggie....



- Stuart -

ok that helped a lot things are becoming clearer thank you much!!!!!!
Stuart that post has established a clearer conversation and a baseline for me to finalize this plan
thank you and xSpace for your support & input it is greatly appreciated!!!!!!!!!!!!!!!!!!!!

Problem is life is eating into my budget, I'm going to have to cut corners and hope for best.

I'm pretty bummed I took the existing layer of drywall I had up on the ceiling down cause it seems at this point, I got middle leaf and 3rd leaf effect no matter what and that I wasted a little bit of money (oh well) cause the drywall that was up there was already serving a purpose as my better than nothing middle leaf. So I guess I got to put a layer back up on the ceiling that I took down great....


I can only afford one layer of 5/8ths drywall (for middle leaf) up on ceiling above joist (or below the joist where it was is easier and at this point I don’t see how it could make a big difference if I put it above or below joist.

I can’t afford to beef up any outer walls.

It looks like I got to go with 3 layers of drywall on inner leafs and one layer of green glue to compensate (hopefully) a little for all the compromises.
If my calculations are correct my ceiling height finished with treatment installed is going to be around 7’9” anything smaller is going to get claustrophobic real quick, so I can’t spare any more than 2” air-gap anywhere, as my room is getting too small to accommodate the vibe I need, so it looks like I’m going to have to live with some compromises (unless I can be convinced otherwise).

I am going to butyl caulk the hell out of everything though for sure (outer leaf/shell and inner leafs of course) unless someone tells me how buytl caulk is not as good as acoustic caulk for sealing.

I hope the following does not come out disrespectful in anyway as that is not my intention, this is just me kinda thinking out loud so bare with me.
In my mind I’m kinda going above and beyond already cause I have personally built a studio where the outer leaf was not sealed, we put up 3 layers of drywall for the inner leafs. No green glue anywhere, no backer rod and we used buytl to seal the inner leafs (yes there are plenty more details than that) and the isolation came out great (4 am full blast live rock band sounded like a faint TV on in next room from 10 feet away and never a single complaint). I'm not saying I'm right or I know what I'm talking about, just saying 3 years later after recent inspection the buytl seals are still solid, flexible, no cracks or holes and the seals do not seem compromised at all + the studio still has same great isolation as it did on day one. So this is my personal experience with Butyl for alternative to acoustic caulk and no backer rod.

At this point I’m already going over the budget and I’m looking at all any additional cost and asking myself are some of these things absolutely necessary etc…

I am going with green glue between on one layer of drywall for sure though (I need all the extra help I can get)!

I mean no disrespect at all its just I'm broke and I'm trying to be practical based on my personal experience, also trying to mix that with your guys expertise as I really appreciate you guys trying to help me do things right and get the best long lasting results. I may have to accept fact that I can’t afford to build a 60 + stc rated studio and be happy with hopefully 50 stc (or close) and deal with the kick drum and bass by not recording those two things past 9pm (as a work around). I'm pretty sure all others sounds will be a none issue and I could mix at 85db at anytime and not disturb anyone. Daytime sounds will drown out the kick and bass and shouldn’t be a problem until after 9pm when people are trying to sleep.

I truly appreciate all the input from you guys and I do need much more help to pull this all off as good as we can do it withing my dwindling budget.

I’m really trying to get to point where I have sorted out all the compromises and I except the plan and commit and build this thing. Any last feedback on the above info?

speech over sorry

AC plan coming soon you’re not going to like it lol

P.S yes I need vocal booth in bathroom this is not commercial studio just for my band (private) and we can live with blinds in vocal booth lol

I know this build has certain issues that make my last build kinda irrelevant, so I am trying to do somethings to insure success while balancing a dwindling
budget.

So I'm thinking about beefing up the outer leaf with a layer of 5/8th's drywall (with the money I was going to spend on the 3rd layer of drywall on the inner leaf).
This would make it actually possible to seal the outer leaf with caulk, as right now the vapor barrier is a major problem to properly seal the outer leaf (vapor barrier is breathable making a airtight seal impractical).
I have attached a pic with notes to see what I'm talking about. Would anyone like to address this issue?

Here is my main question though

If I can only go with 1 layer of 5/8ths drywall on ceiling below joist for my middle leaf, is it even worth beefing up the outer leaf walls?

wheres the beef

It isn't a vapor barrier. It is house wrap that is supposed to breath. This materials ability to allow the passage of air and diffuse condensation doesn't have anything to do with the assemblies ability to become airtight.

The only real question from where I sit is why am I seeing the house wrap when the proper installation for this material is on the exterior/outside face of the buildings sheathing?

back to this question though

If I can only go with 1 layer of 5/8ths drywall on ceiling (below joist for my middle leaf),
is it even worth beefing up the outer leaf walls?
Also I got a question about caulking the beefed up layer, is it ok to just caulk/seal that layer only
or is sealing the existing outer layer recommended too (double seal)?

If I can only go with 1 layer of 5/8ths drywall on ceiling (below joist for my middle leaf),
is it even worth beefing up the outer leaf walls?

50/50. Meaning it can't hurt, and would be good in case you ever do mange to do the ceiling / redo the roof. For example, if at some point in the future you replace the roof with a plywood deck and asphalt shingles... Doing it now costs a little more, but will help slightly, and is a whole lot easier than trying to do it later! Taking off the tin and putting on a plywood/shingle roof is "easy". Taking down all your walls to do them again is not so easy....

So, yeah, if it were my build, I probably would do it, even knowing that it won't have a huge effect right now.

Question: is there any way you can beef up that roof structure to get TWO layers of 5/8" on it? Now THAT is worth doing... The worst case for a three-leaf is when the middle layer is low mass. The best case is when it is the heaviest of the three, with the most mass on it.

Also I got a question about caulking the beefed up layer, is it ok to just caulk/seal that layer only or is sealing the existing outer layer recommended too (double seal)?

I'd do both, if you can. One seal is enough, but you never know when a small part of it might fail. Two seals takes care of that.

- Stuart -

update

took down all tyvek and got to caulking.
Over the past week I did a test between green glue caulk, butyl and cheap 40 year caulk
after a week the cheap stuff is a little harder than the others but not rock solid still pretty flexible, has not shrank and pretty acceptable IMHO.
I took a chance and used 40 year caulk as this seems good enough for me so I did half the room today.

"Over the past week I did a test between green glue caulk, butyl and cheap 40 year caulk"

Your test data is hardly of any value to you. In order to really understand the long term, you should give it six months THEN let us know how hard the 40 year caulk is.

Acoustic caulk should have been in your test sample, it's what you should be using.

Your test data is hardly of any value to you.

I'm also wondering how you go about testing the acoustic properties of something, without having an acoustic test laboratory...


- Stuart -

Sorry guys had to try to save money where I could
and cut corner on outer leaf caulking.
my friend reported ok seals with this stuff a year later.
I will buy the good stuff acoustic caulk
for my inner leafs!

How about beefing up outer leaf and
doing 2 layers on my middle leaf ceiling.
Is beefing up my outer leaf worth it
if I get 2 layers of drywall on middle leaf ceiling?

The owner of house is not ok with me
taking corrugated roof down n putting mass up
there so got to live with middle leaf.

Also if I stay with my 2" air gap everywhere
does this mess up my isolation plans?

ok its official my stubborn broke butt just got enough extra funds to beef up outer leaf with 5/8ths drywall and add 2 layers of 5/8ths to my middle leaf ceiling.

I got the outer leaf layer 1 all caulked and I'm starting to put up the 2nd (beef) layer on the outer leaf (cutting up
drywall into little slats to go between the studs).

On the inner leaf I will be going with 3 layers of drywall, one layer of green glue and acoustic caulk on all seams.

Just hoping I can live with the 2" air gap everywhere?

going over budget and behind schedule

Is 2" airgap going to kill me based on above?