Absorbent Open Ceiling

Hello - I asked this question in another thread I'd started but It was a bit off of the original topic, so creating a new thread - hope that's ok. Planning to redo my basement into a better mix environment. The basics: Room will be small, 91.25"H x 145"W x 168"L. 3 Walls are concrete: Insulation/Frame: 5/8" Drywall - 4th wall is drywall on both sides of insulated frame. Floor will be concrete. I'm not so concerned about isolation or soundproofing; I just want a better sounding listening/mix room. Treatment plans so far are for a bare minimum of 4" corner traps (3 of 4 corners) and 2" panels at mirror points and back wall. Part of the plan is to create an absorbent open ceiling with a fabric covering rather than drywall. So have a couple of questions about that. First off, what type of insulation should I use for the exposed / fabric covered absorbent ceiling? I'm assuming I want the fluffy stuff that will fit between the 8" joists but what rating would be acceptable - R-19, R-21, etc? Also would i install the insulation with the paperside facing the room or with the paper side backed up against the underside of the floorboards above? Or should I alternate paperside up, paperside down across the ceiling? Theoretically I can see a pro and con to each scenario, but what would you guys recommend? I will be removing all carpet so I'll be left with a concrete floor which I plan on painting. Secondly, I'm wondering if the fiberglass panels I currently have as my drop ceiling can be used as mid/high absorbers once I start treatment inside the room. They're the typical 2'x4' fiberglass panels you would buy at home depot with the white plastic/vinyl facing on one side. They're only 1/2" thick but I'd imagine there would be no harm in gluing multiple panels together. The plastic facing tears off easily and I could easily glue enough together for 4 or 5 2'x4'x2" panels that I could use for treatment later. The only thing I don't know is the density of this type of panel. Would these suffice or should I just trash them and buy new 2" panels of the OC 703 variety as planned? Thanks for all the help - This forum is great :)

Haha.. i just posted my answer on the other thread. -- John

jhbrandt wrote:

These will work fine in absorption panels or whatever. If you got it.. use it.

Well that's a nice and welcome surprise. I wasn't sure if the density of these type of panels would be appropriate. If they'll work, I'll make my side and behind speaker absorbers out of these. Then I'll just have to buy enough new fiberglass for corner bass traps. Is 703 still the best material for building corner absorbers? I know there's some alternatives out there now that may be easier to work with and/or better at absorbing low frequencies. Would you recommend any of them over the 703? Planning to go at least 4" thick, Possibly 6" if I can afford to on as many corners as possible.

jhbrandt wrote:

Paper side UP. Make the ceiling fully absorbent. R-19 is 6.25" thick, R-21 is 5.5", R-30 is 9.5" thick. Get the thickness that you need to fill the joist space.

Ok - looks like r19 is the one for me then as I have 8" joists. How is the quality of alternative insulation materials - The cotton batts or the safetouch / fiberglass free type stuff? I like the idea of not itching for three days after getting dirty with the fluffy stuff. So my building buddy was over here today to have a good look and when I mentioned stapling the insulation to the underside of the floor boards (My ceiling), he advised me against that and said I should leave some air space between the paper and the flooring to create a vapor barrier (or something to that effect). I explained that I wasn't sure what acoustic effect that would have, and how some of the construction methods we'll be employing through the build will be different than what he's used to. He's on board with that and willing to do whatever's necessary. I just have to be specific with him. This ultimately means I'll be asking a lot more specific questions around here over the next couple of weeks - so I really do appreciate the help you've offered :D But for now, should there be an air gap between paper facing and overhead floor (stapled to joists)? Or paper facing stapled directly to the underside of floor boards? Thanks again.

An air gap won't hurt it... We usually place the batts between the joists so they are held in place with string until the fabric is installed. I usually do not use the frk type for stuffing floor joists from a basement that is otherwise occupied/heated, etc. Using the frk may make installation easier by stapling it to the joists to hold it in place until the fabric is installed. Whatever is easier - it's not rocket science. ;) As for alternatives to O/C 703, -- the specs are not the same, Bob Golds Absorption coefficients page has a listing. http://www.bobgolds.com/AbsorptionCoefficients.htm Cheers, John

jhbrandt wrote:

it's not rocket science

It is science though :) And it sure seems like rocket science when you're first learning. The more I research the more questions I'm left with :-| Thanks for the Bob Gold link. Hard to predict how much absorption I'll need at specific frequencies though so I'm not sure the ratings mean much to me at this point. I figured I would just go with the 703 since it has a proven track record but having trouble finding in Philadelphia PA. The big guys around me carry Johns Manville, Certainteed, and Armstrong. Haven't seen Roxul or Owens Corning yet though. And so far the "help" there hasn't been able to provide me with a similar density alternative. I need to save where I can - I'd like shipping to be one of those places. Could anybody recommend a product from one of these companies for building 6" low end / broadband absorbers - preferably a product that they've actually worked with?

Wait!!! Do NOT buy OC 703 for the ceiling joist cavity! NOT cost effective. :cop: Simply fill the space between the joists with standard building insulation - the pink stuff - Attic blanket. This is available at Lowes and Home Depot - very cheap. :wink: Get 703 for wall panels that you will need to build. Cheers, John

Certain Teed: OEM 300 Johns Manville: Incombustible Hullboard try those for your acoustic panels. - John

jhbrandt wrote:

Do NOT buy OC 703 for the ceiling joist cavity! NOT cost effective.

No - wasn't considering that. 703 (or more likely one of your alternative recommendations) would be for reflection points and corner absorbers. Thanks for heads up though. :wink: So when you do a ceiling that this with the joints exposed and no hard ceiling, I'm assuming you need to use clips to attach the new wall frame header to the joist bottoms in order to decouple the 2 leafs. Which specific type of clip do I need for this purpose? Economical is good if you can recommend a specific model or retailer to purchase from. Still trying to figure out how to close off the area between the joists and above the wall frame. The joists obviously extend to the outer stone/cement wall. But without a hard ceiling to close off the top of the new wall, the area between the joists / above the new wall / to edge of outer wall would remain open. If I attach 2x4's to joists to mount drywall in the gaps between the joists, then the the joists would actually be coupling the inner and outer walls. Any ideas how I can close that area off without a hard ceiling? Hope this makes sense. Heres a pic of the joist space in question.

you can use anchors (like the floor) to attach inner wall top plate to the joists or resilient braces like WIC or the Kinetics equiv. for the ceiling, you can use hat channel on resilient clips (Kinetics, RISC etc) and attach the inner ceiling drywall there. fill that space with pink insulation. you can then use the ceiling tile tracks to hide any ducting and wiring and flush mount lighting etc. plus some absorption from the tiles.

??? Glenn - Forgive me if I'm misreading your reply, but It sounds like you think I'm doing a drywall ceiling. I'm not on account of the already low height and pipes that extend well below the joists. I was planning to go with a fabric covered ceiling with insulation between the joists. So there would be no inner ceiling drywall nor a ceiling grid for tiles like you see in the current picture. Sorry if I wasn't clear about that.

gullfo wrote:

for the ceiling, you can use hat channel on resilient clips (Kinetics, RISC etc) and attach the inner ceiling drywall there.

Are you referring to the space between joists? Hat channel and clips mounted between each joist? I think this is where I lost ya.

Gotcha. You should look at fire blocks to both be safe and partially seal off the space. By compress rigid insulation and then a layer of drywall (not directly contacting) and caulked, you will probably be as close as you'll get. Check out Rod's book for details on properly constructing the fire stops.

Modini wrote:

gullfo wrote:

for the ceiling, you can use hat channel on resilient clips (Kinetics, RISC etc) and attach the inner ceiling drywall there.

Are you referring to the space between joists? Hat channel and clips mounted between each joist? I think this is where I lost ya.

My fault. Didn't see the open ceiling design.

gullfo wrote:

Gotcha. You should look at fire blocks to both be safe and partially seal off the space. By compress rigid insulation and then a layer of drywall (not directly contacting) and caulked, you will probably be as close as you'll get. Check out Rod's book for details on properly constructing the fire stops.

Rigid insulation and a layer of drywall where? Vertically along the inside of the joists (flush with the new inner wall)? So there would be 16" by 8"ish drywall panels mounted between each joist? Am I following?

between the inner wall and outer wall and gwb on top. updated pic

Oh- You're still talking about the firestop. Ok - Thanks for the diagram. Will def plan for firestops within the build. In the meantime though... I still need to figure out how to close off the area between the joists though without coupling the inner and outer walls. New wall will be attached to joists via some type of iso clips. OK so far. But that would all be pretty pointless without sealing off the area above the wall where sound could travel right over the new wall. Was thinking I could cut 16" panels of drywall to fit between joists and mount to joists. But then if i seal / mud / tape the bottom of these panels to the top of new wall, I'd be effectively coupling the walls since the panels would now be bridging new wall with existing joists. UGH! I'm so confused and I'm starting to get pretty frustrated. The learning / research is literally taking up all of my free time and not being a builder doesn't help any. I really need to get started with my build here or I'm going to run out of time to build before I need to start another music project. I'm seriously close to giving up. Is there like a studio builders hotline that I can call for quick answers or something? I love the help I'm getting here but I really need to pick up the pace and it would really help to actually talk to someone about my questions. Forums are great and this one especially has been super helpful and informative. But there's nothing quick about the forum platform when you're the one asking questions. I've been pondering this one question for over a week now and still have no answer. I feel like 3 minutes of actually talking to someone would have answered this question and more. Somebody seriously should set up a studio construction hotline - They'd def get my business right about now :)

put in something like plywood cut out from the joists to fit up into the joist space and layer the drywall on it and using backer rod and caulk to seal.

hmm...interesting. I would not of thought of that. I would've assumed that the plywood would act as a direct connection between inner / outer leaves. So is the backer rod and caulk enough to decouple the inner wall frame from the ceiling joists? would you screw the plywood directly to the frame and joist? Also what's the reason for plywood instead of sheetrock for this task? Appreciate the sketchup :thu:

the plywood is only attached to the inner wall and extends into the joists but does not touch anything. this is the backing for the drywall which extend up there as well. not sure what you're trying to achieve from isolation and this might not be useful anyways since there open ceiling means you have little or no isolation anyways.

Well it's true that total isolation was never a goal - a better sounding room is the main priority. But I figured I may as well get whatever isolation improvements I can during the build - I really don't like the wood paneling look in here so wanted to get rid of that anyway. And I have about zero isolation from neighbors right now (I'm in the basement of a row home). So I figured anything more than the 1/4" paneling/no insulation/ wood frame touching outer cement/stone walls that I have now would be a welcome improvement to my neighbors. They say they don't mind the noise (I've asked), but i figured if I could help the situation I would. But am I wasting builders time / my money by trying to decouple the walls with an open ceiling? I was planning on attaching 5/8 drywall to the underside of the floorboards before laying insulation and covering with fabric to help with the noise from above - The family room TV is right above me and without the ceiling tiles now I can pretty much hear it clearly. So here is where isolation would actually benefit me the most. Unfortunately I can't do a hard ceiling in here as I would lose at least 13" height in clearing the joists and pipes running beneath them. I had a tiled ceiling grid at this height and it wasn't comfortable. Though I'm surprised how much my rinky-dink 1/2" fiberglass panel ceiling helped with the TV noise from above.

fiberglass isn't isolation. you don't need the entire ceiling to hang below the pipes. you could potentially put the drywall on the isolation clips and hat channel so it sits between the pipes and joists. or box out around the pipes if needed. then the wall-ceiling seal is much better.

I realize what you're suggesting is a better way of doing it from an isolation point of view. But it also opens up another can of worms that I'm not eager to take on; Ceiling cloud on an already low ceiling, More expensive, difficult build/ installation,etc. So I'm looking at a hard ceiling as a last resort option. The drywall on the underside of the floorboards should help enough with the TV noise above I would think. So assuming I go along with my plan of the open ceiling, is it even worth the added expense / trouble to decouple my walls from the ceiling joists?

i'd say no decoupling won't do much. but i'd also consider decoupling them just in case later you decide to add the drywall ceiling.

I was afraid you would say that. Really starting to feel like I'm chasing my tail here. Is it safe to assume then that folks who have open fabric covered ceilings have little to no isolation on any side of them? Wish I knew before that one was not possible without the other. Another weeks prep/planning down the tubes :( So even the plan/diagram with the frame notches and plywood backing you had suggested would be a waste then?

The secret is that the "open" ceilings may be inside-out ceilings or there's another isolation layer. So, you could try to beef up the ceiling with multiple layers of drywall to increase the mass but understand that the impact noise etc will likely not be resolved. But you would still have the option to add another ceiling and then achieve a pretty high level of isolation.