Like many others here I am going to be finishing my basement and have everything determined except for the ceiling design.
The basement will be used for recording and I will also have a home theater room as well as an exercise room down there. The point is that I am will probably employ different ceiling construction techniques depending on the sound attenuation required, cost, and labor for the install.
The ceiling is 3/4" hardwood on top (floor), then 3/4" OSB subfloor, 2x10 joists, cavities filled with insulation, then one of the following to finish it up:
1. RC (probably RC6) and 1/2" drywall
2. RC (as above) and two layers of 1/2" drywall
3. Isomax clips, hat channel, and 1/2" drywall
4. Isomax clips, hat channel, and two layers of 1/2" drywall
Can somebody tell me how these 4 designs would compare in terms of STC, assuming proper construction, no short circuits, proper sealing...?
Or at least can you tell me in a relative way which would provide the best sound isolation to the worst?
I would assume that #4 would be best and #1 worst, but I'm not sure about #2 and #3. I'm also not sure how they would difference in terms of relative STC. i.e. #4 is xdB better than #1.
All "gut check" estimates appreciated!
Great forum!
- Mark
Please rank the effectiveness of these 4 ceiling designs
Originally posted at johnlsayers.com, topic 7784.
Well I guess I'm being punished for not posting all of the information "required" in the "don't post until you read this" sticky.
My question is more of a theoretical one in nature than one of "what should I do?" As a mechanical engineer I am quite familiar with analying various possible construction methods and determining the optimal solution. In this case all I needed was a few opinions on the ceiling designs indicated.
Anyway, the worst design would be the RC and one layer of drywall. Next better I think would be the RC with two layers of drywall and I would estimate the second layer of drywall's mass and therefore increased damping properties would yield 3 or 4dB increased noise attenuation.
After that probably the IsoMax clip solution, most likely providing 3dB more attenuation over the previous setup. Finally the IsoMax clips and two layers of drywall would probably provide an additional 3dB of attenuation.
Of course this assumes no short circuits in the constuction of either assembly.
There that should do it. Now I do know what to do. Thanks for making me figure this out myself. I should have just taken the 20 seconds of thought this required and done this in the first place instead of wasting everyone's time posting.
Rock on fellas!
Greetings and Welcome to the site Mark.
It's the holidays, so probably everyone has been away from their computers that last few days...???
If you could also include what part of the world your located in, would be helpful.
In terms of drywall...use 5/8" not 1/2". The basic rule of thumb is "Mass, Air, Mass".
Depending on your isolation requirements, will depend on how you construct your walls and ceiling. Keeping in mind that isolation isn't just a one part construction, but rather an assembly of everything together.
Other things to consider, your dead weight load on the joists, and the spans. Be sure it will support the extra thousand pounds or so of drywall.
You are correct in option #4, just change it to 5/8" drywall instead 1/2". You also may consider the Green Glue product to sandwich between the 2 layers. And the other is to be sure you stagger your joints between the 2 layers as well as seal the corners w/ acoustical sealant.
I am located in Columbus, NJ.
Since I'm finishing a basement I'm using pressure treated 2x6's to provide fireblocking. This wood will be firestop caulked against the foundation walls so flanking noise behind the wall and up through the ceiling should be effectively blocked. Transmission through the wall studs and through the fireblocking should also be substantially reduced due to the "inertness" of the foundation walls and slab floor. The connection point of the top plate to the joists is one transmission path but as I said since the top plate will be anchored to the foundation wall I don't think there will be much vibration potential there.
I had all joists doubled upon construction of the house as it was a pretty inexpensive upgrade. I knew I'd be doing this. They are all double 2x10, 16' span. Minimum deflection is L/537. The additional dead load won't be a problem.
One other question. I was planning on using some recessed lights and now I'm thinking no matter how well I seal them they'll seriously compromise my ceiling.
Thanks for the tips!
You are correct. Any holes, especially lights will compromise your isolation. You can hang clouds w/ recessed lighting though...(below your hard ceiling)One other question. I was planning on using some recessed lights and now I'm thinking no matter how well I seal them they'll seriously compromise my ceiling.