one pane is 3/8" and one pane is 1/2". if each one is laminated from thinner glass that is ok. the mass of the glass should be close or more than the wall. a typically drywall is about 2.2lb/ft2 so 2 layers is about 4.4lb/ft2. 3/8" glass is about 5.1lb/ft2. so the 3/8" glass would work on the 2x drywall and 1/2" would be a good fit for 3x drywall. one thing is to use a mix of glass thickness to reduce coincident resonances between the glass panes.Do you mean to laminate the 3/8ths to the 1/2" or laminate the 3/8's to the 3/8ths until the required thickness is reached, then the same for the 1/2" 2nd pane? Is there a way to calculate how thick the glass panes should be to match the wall stc?
Exterior wall concept
Originally posted at johnlsayers.com, topic 15096.
not, absorption. the slats on the super chunk keep some life up there and the hangers take some away. the actual numbers positions and sizes depends. if the drywall sits on the inside of the truss, you would just lower and adjust things to fit. this drawing is really about the concepts.Do the hangers function as low end diffusion?
I figured that you were on thatyou would just lower and adjust things to fit. this drawing is really about the concepts.Do the hangers function as low end diffusion?
I'm trying to figure the best way to do the ceiling in the main rec room.
Is there a way to calculate what kind of performance i would get from this set up...
-2 layers of 5/8ths DW on the inner side of the trusses.
-this style of iso clips
http://www.kineticsnoise.com/arch/isomax/index.aspx
on top, then 2 more layers of 5/8s DW.
My concern about this approach is lack of an adequate air space.
There is this one as well http://www.kineticsnoise.com/arch/ksch.aspx but i don't think it can used on an angle, it would put the wrong pressure on the springs.
I was looking at using hangers( http://www.kineticsnoise.com/arch/icw/index.aspx ) to support a grid but given that the inner roof is sloped(4-12) i don't think i can use those(for the same reason as above) and i don't want to make it flat and lose cubic feet.
Initially i thought i could use the air space inside the trusses but there needs to be airflow in there.
Am i missing an obvious solution?
add the additional 2x mass on the exterior roof then use the clips + channel + 2x mass on the inside of the trusses. that should leave plenty of air space. R30 (or more) on the inner ceiling to dampen.
Like i said, i can't. There is a required airspace on the sides of the trusses where the soffit goes, all the sound just goes out there, it's too big to make it a hot roof.add the additional 2x mass on the exterior roof then use the clips + channel + 2x mass on the inside of the trusses. that should leave plenty of air space. R30 (or more) on the inner ceiling to dampen.
This is what i have so far as a best option
http://www.kineticsnoise.com/arch/tests/pdf/E2-c.pdf
The 2 layers 5/8ths dw go on the trusses, then wood blocks on top of the drywall through to the trusses where clips will attach to create the air space, then a steel stud grid on the clips, insulate and drywall again.
then go with the option you've shown. maybe you can use 1 more layer of drywall and green glue on the inner face to get some additional isolation.
I kind of can make the air space as large as i want to a certain degree. Do you think 3.5 inches is sufficient?then go with the option you've shown. maybe you can use 1 more layer of drywall and green glue on the inner face to get some additional isolation.
The other concern is to have some holding power under that 2nd ceiling layer to hold the diffusion etc up there. Will the steel stud grid be ok for that?
you could consider some isolation hangers attached to the truss specifically to support the diffusers and other treatments. or reduce the distance o.c. between members on the grid to accommodate the loading.
any thoughts on the air space?
it sounds like you have a limit on the air space available so it's going to be one of those compromises.
Does this work, or could it be done better?
I want to avoid putting drywall on the outside of the outer wall obviously but am i in danger of a 3 leaf system here with the osb sheeting out there? It's not sealed in fact there are 1/8" gaps between sheets.
(that should be 4-6" not feet on the air gap obviously)
it will be a third leaf to a certain degree but the exterior wall density is lower than the two inner drywall layers so you might have some respite there. if you use those 2 drywall layers on the outside of the inner wall to beef up the exterior wall (layers of drywall between the studs you will likely be better off.
Right, pardon the clarity of the pic, but the drywall in between the studs should be attached to the inside of the outer wall, not the outside of the inner wall. Is that what you mean?it will be a third leaf to a certain degree but the exterior wall density is lower than the two inner drywall layers so you might have some respite there. if you use those 2 drywall layers on the outside of the inner wall to beef up the exterior wall (layers of drywall between the studs you will likely be better off.
yes, inside of the inner wall or outside of the outer wall... sorry for the confusion
No you lost me again. The outer wall is the shell of the building, the inner wall is the secondary steel stud wall for sound purposes only. Does the middle layer of drywall(between the walls) work better on the inside of the shell(building) wall or the outside of the inner(steel stud sound wall) wall? Or are you suggesting i put drywall on the outside of the building?yes, inside of the inner wall or outside of the outer wall... sorry for the confusion
Put the drywall on the inside of the outer wall sheathing to build up the mass. Then then inside of thumper wall. This will give you the proper mass-air-mass you need.
Doesn't the sheer membrane need to be attached directly to wall studs as a matter of code? Putting on 2 layers of drywall first will put some serious weight on the structure before the osb goes on won't it?Put the drywall on the inside of the outer wall sheathing to build up the mass. Then then inside of thumper wall. This will give you the proper mass-air-mass you need.
ok, let's re-start...
outer wall sheathing attached to outer wall studs per code. BETWEEN the outer wall studs are 2-3x layers of drywall held in place with cleats. use backer rod and caulk to seal. pink insulation to fill. inner wall is studs and between them is pink insulation then 2-3x drywall layers. this way you have mass-air-mass. ensure the inner walls respect code by proper fire stopping and stabilizing. all decoupled. do not over pack the insulation, air is your friend.
if you have no purchased Rod Gervais's excellent book on home studio construction i recommend you get it ordered today. http://www.amazon.com/Home-Recording-St ... 43545717X/
Glen, i really appreciate your help. But this just is not making sense to me. Is there a picture you could point me to? I have several books on the subject and have been reading them. I have also researched wall design a fair bit. This outer building wall never seems to get addressed though and i want to be sure i understand how to do it right. The line above is not clear to me, it could mean cutting little strips of drywall and putting it in between the studs for all i know?? If it is as simple as using resilient channel and adding 2-3 layers of drywall to the inside of the outer wall then fine, but i am not getting a clear description of that from your posts. Please post a pic if you can find time. Again, i appreciate your input very much, thanks for taking the time.BETWEEN the outer wall studs are 2-3x layers of drywall held in place with cleats. use backer rod and caulk to seal. pink insulation to fill.
Bingo! Yup, that's exactly what Glenn is talking about. You sometimes see it referred to as "beefing up" the outer leaf from inside the wall. You do exactly what you are saying: cut pieces of drywall so that they fit in the areas between the studs, pressed up tight against the drywall that is already on the studs, and you hold them in place with cleats, then seal around the edges with caulk. If you need even more mass, then add another layer. - Stuart -The line above is not clear to me, it could mean cutting little strips of drywall and putting it in between the studs for all i know??
Ok i get it. New concept to me, but it makes sense. I ordered the book tonight. Thanks for the tip Glen. Although, are we not stopping the needed airflow from the outside to the vapor barrier on the inner side by sealing the outer membrane off? The original wall would be, outside to inside: -1/2" osb -studs filled with pink insulation -vapor barrier Sealing off the outer shear membrane with acoustic sealant on the inside along with drywall as you suggest would also seal off the pink insulation and cause a condensation problem wouldn't it?Bingo! Yup, that's exactly what Glenn is talking about. You sometimes see it referred to as "beefing up" the outer leaf from inside the wall. You do exactly what you are saying: cut pieces of drywall so that they fit in the areas between the studs, pressed up tight against the drywall that is already on the studs, and you hold them in place with cleats, then seal around the edges with caulk. If you need even more mass, then add another layer. - Stuart -The line above is not clear to me, it could mean cutting little strips of drywall and putting it in between the studs for all i know??
why would there be condensation in that space because you add drywall? you don't have air flow through there now? most construction uses an exterior vapor retarder to seal the building. then again, if you need to ventilate that space you'll have to consider some form of baffled air flow to ensure isolation.