2. tech-talk
  3. 1291840175

Ceiling tiles using rigid fiberglass

So I'm in the process of finishing a basement to include a dedicated audio space, which will be 35' x 23' x 8'6". Walls framed and electrical mostly done. I am trying to determine the most effective method of creating an acoustically absorbent ceiling while maintaining a nice look.

I have looked into 'acoustical' ceiling tiles but the data is obviously not promising. The idea that I favor right now is to buy the rigid fiberglass, cut it into 2' x 2' squares, wrap them in an acoustically transparent cloth, exact type TBD, and drop them into a standard grid. In effect, I'd be creating my own ceiling tiles, the benefit being that they'd actually be of acoustic benefit, instead of the off-the-shelf tiles which don't work all that well.

The main questions I have are:

(1) Is this a reasonable approach? Has anyone here tried this?
(2) If so, what to do with the gap between the rigid fiberglass and the main level floor (joists are 2x10s)? Is it best to use 1" rigid and stuff the rest with fluffy, 2" and stuff, 4" and stuff, or will they yield similar acoustic results? If I use 4", will stuffing the gap even make a difference? I think the 1" rigid plus fluffy is the least expensive option, but performance is more important that cost here.

I'm also very open to ceiling tiles which are acoustically transparent enough to let the incident waves penetrate to fluffy fiberglass underneath. This would be a very attractive option, as it may yield great performance with less effort (I'm doing all the construction work myself, so anything that saves time is welcomed!).

Apologies if this has been posted elsewhere, but I searched for quite a while.....

Thoughts?
cathode
hessec's avatar
hessec
59 posts
 
So, you are looking for a whole ceiling of absorption? Or is the goal to "soundproof" the room from the upstairs? I am certainly no expert but I have been messing around with my own diy rigid fiberglass creations for a while and I think that the whole ceiling covered in 705 would sound awful. In this application, I don't know for sure, but these panels can be VERY effective at sucking the life out of your stereo..... I don't know how else to put it. If it were me, starting over, I would drywall it and then mess with placement for a while of panels on the ceiling, mark out the spots you think sound the best for the traps and then finish (i.e. paint, spackle) and finally permanently attach your panels.

There is a lot more proper acoustics than just absorption (diffusion) and you would be well served to do a lot of research before going off the deep end..... Just my opinion.
tonywinsc
583 posts
 
I agree with Hessec. Too much absorption will suck the life out of the music. I experienced that back in the early 90s using anechoic foam panels. (We had leftovers from our NVH chamber that we built at work). Drywall the ceiling. Use insulation to isolate the music from the upstairs area, if you want. Treat the corners and upper middle ceiling to wall interface with sound absorption. Just vary the amount of treatment to acheive what you want. Low frequency sound waves are very long and require deep insulation (>1 foot) to be absorbed. Thin panels will mostly absorb high frequencies. Corner treatment cuts down mid-low frequency reflections which makes the bass sound clearer. That is my experience.
azjake's avatar
azjake
284 posts
 
Tonywinsc has given you a wonderful and easy to follow tutorial!

may i add that the corner treatments [or traps] will also go above 100hz to deal with time smear on the mids... A bonus if you will...:-)

Good luck and look up MSR "clouds" for your ceiling!
palasr
516 posts
 
If you are indeed looking for better soundproofing between the two floors, I'd recommend using something like Quietrock 530 or Soundbreak XP. Standard drywall solutions leave quite a bit to be desired as far as STC ratings are concerned. I used both products in constructing my new sound room, and the differences are not subtle. Combined with an insulating product such as Roxul Safe N' Sound, you significantly decrease sound transmission without resorting to more expensive framing solutions (staggered stud, double walls, etc - although these add yet more isolation for excellent STC ratings). Have fun, and remember the work will be worth it in the end!
kijanki's avatar
kijanki
4,394 posts
 
Cathode, I'm making twelve 2'x4' 2" panels using Johns Manville 817 rigid fiberglass panels http://www.jm.com/insulation/performance_materials/products/ci9_800series_spin-glas.pdf

I considered Corning 705 but sound absorption coefficient at 125Hz is only 0.16 (almost not working) while Johns Manville 817 is 0.38 - much better. 125Hz absorption is important to me on the walls but I'm not sure if it applies to ceiling. I had an option to go to 4" panels (much better at low frequencies) but there is WAF.
More to discover