John Sayers' Recording Studio Design Forum Archive

I just bought Rod's book and he states that you shouldn't use resilient channel on the walls in a double wall build. Do you guys have any comments on this? I want to finish my basement. Three of the walls will have poured concrete as the outer wall, so I was thinking of 2 by 4 framing using rcis on the inner wall, placed about an inch from the concrete wall.


I also had a question about the bottom and top plates of a wall construction.

Do you put anything under the bottom plate such as sill seal, caulk, rubber gasket or anything or just nail or bolt it to the concrete floor. What about the top plate? Does this just get nailed into the ceiling joists? Will there be any flanking if this framed wall is in contact with slab and joists?

Welcome Peteys:

I can't answeer your second question directly, but the first is almost too easy to answer:

I just bought Rod's book and he states that you shouldn't use resilient channel on the walls in a double wall build. Do you guys have any comments on this? I

Rod is right. If you want ot get acoustically picky, there is no acousitcal reason that you can not use RC in that application it will just empty your bank account.

Andre

peteys - the reason for RC is to limit the transfer of the sound through the stud wall timber to the second layer of drywall by lifting it off the stud. If there is no drywall on the other side there is no advantage in using it.

With regard you bottom/top plates, just make sure there is a good seal. remember -

a sound proof room is an airtight room.

cheers
john

Using a "Sill Seal" type product gives you a capilary break as well as a draft stop.

--Keith

I agree 100% with Andre. It's not that you shouldn't, it's that there's no need to.

Also, IMO, I don't use RC in any situation unless I'm forced to. While it does an OK job of isolation, it's way too easy to mess up and it's very unpredictable as to how the room inside will react. To me, RSIC-1 and hat channel is a far superior solution - but you don't need that on a double wall either

Bryan

petey as to your second question it depends on what you want to achive and budget try www.fabreeka.com they specialise in this

"To me, RSIC-1 and hat channel is a far superior solution"

This is what I was thinking I would use for the ceiling. Now I can save some money and extra work by not using it for the walls. Thanks guys, this forum rocks.

Just remember if you're doing ISO walls and RSIC-1 on the ceiling, you don't want to tie the walls to the ceiling and defeat the whole purpose - use DC-04 clips to decouple the wall from the joists above.

Bryan

Aren't those garage door silencers? I was thinking that I would attach the concrete wall to the framed wall with some special clips I was reading about(every 8 feet)in some way and then install the ceiling with rsic-1/ hat channel to the ceiling joists a 1/4" away from the framed and sheetrocked wall. Would there be a better way that you were describing?

In other words, my top plate for the wall would never be attached to the ceiling joists; they would be attached to the poured concrete wall.

I'm also wondering how, if practicle, it is to have recessed lighting in the ceiling without losing isolation. What i've read is framing a box in the ceiling for them. That seems like a lot of work. Does anyone have any experience with this or is it just easier to use track lighting?

pete

Remember that sound travels in 2 ways - through the air and through the structure. You need to fix both to get real isolation.

The mounting of walls to concrete with clips and not tying to ceiling helps with the structure. Turning around and cutting holes in the envelope for lights is defeating the purpose as you just lost all of your air isolation.

If you must use cans or other recessed fixtures, definitely build boxes up in the ceiling to keep the isolation. Yes - it's a lot of work but worth it to get the iso.

If you're not going to build the boxes, don't bother with the cost for the rest.

Bryan

If you're not going to build the boxes, don't bother with the cost for the rest.

Hey bpage, about these light can enclosures. Do they "rest" on the drywall so to kinda float with it, or are they "decoupled" and sealed? I've never seen this done so I don't understand the geometry/construction. Are these lined with drywall? I was under the impression cans needed ventilation above them, like an attic space. I would seem if you enclosed a can in a small airproof sealed box, that it would get very hot in them. How does one reconcile this potential fire problem? Some cans can't be closer than 3" even from fiberglass insulation they get so hot.
fitZ

peteys wrote: I also had a question about the bottom and top plates of a wall construction.

Do you put anything under the bottom plate such as sill seal, caulk, rubber gasket or anything or just nail or bolt it to the concrete floor. What about the top plate? Does this just get nailed into the ceiling joists? Will there be any flanking if this framed wall is in contact with slab and joists?

Peteys,

I also cover this in the book -

If you properly seal the drywall at the perimiter of the wall - then you don't need to seal under the bottom plate.

If you seal under the bottom plate and don'tproperly seal the drywall - then you haven't gained anything -

So either way - a seal under the bottom plate is ust throwing your money away.

As to the ceiling - I give quite a few details in there on how to isolate walls from ceilings.......... they work.

Sincerely,

Rod

cadesignr wrote:

I was under the impression cans needed ventilation above them, like an attic space. I would seem if you enclosed a can in a small airproof sealed box, that it would get very hot in them. How does one reconcile this potential fire problem? Some cans can't be closer than 3" even from fiberglass insulation they get so hot.
fitZ

fitZ,

they make zero clearance cans - ones that you can insulate tightly around - you have to use these cans if you are placing them inside of a box.

And no - the lights do NOT float over the ceiling - they are installed mechanically attached with their own hangers.

Sincerely,

Rod

[quote="bpape"]I agree 100% with Andre. It's not that you shouldn't, it's that there's no need to.

Bryan,

Actually - it's that you shouldn't.

You get a low frequency penalty for using RC versus wood stds alone once you begin isolating walls from one another.

It is ever so slightly noticable if you check IRC-761 and look at staggered stud walls - 2x4 construction - layers of 5/8" each face - with fiberglass insulation - and then add RC to one side - and then to both sides.

The effect is in the lowest numbers - namely 50 and 63Hz.......... but remember that it our lower frequencies where stiffness comes into play - so it's more important that it might seem if you are tryiing to acheive increased isolation levels at very low frequencies.........

Here's the 3 staggered conditions measured in IRC 761 for this:

5/8 - 2x4 – 16” centers – staggered – fiberglass insulation 5/8

TestID TL-93-248
STC 49

50 Hz 14.8
63 Hz 18.9
80 Hz 21.0
100 Hz 22.2
125 Hz 24.9
160 Hz 29.3
200 Hz 35.1
250 Hz 44.0
315 Hz 45.6
400 Hz 48.3
500 Hz 49.5
630 Hz 51.4
800 Hz 54.1
1000 Hz 56.3
1250 Hz 57.6
1600 Hz 55.8
2000 Hz 48.3
2500 Hz 47.6
3150 Hz 53.2
4000 Hz 58.6
5000 Hz 63.4
6300 Hz 69.4


Add RC one side

TestID TL-93-214
STC 51

50 Hz 14.5
63 Hz 15.7
80 Hz 21.9
100 Hz 22.5
125 Hz 26.8
160 Hz 33.0
200 Hz 39.9
250 Hz 46.4
315 Hz 50.8
400 Hz 55.1
500 Hz 59.1
630 Hz 61.4
800 Hz 65.0
1000 Hz 66.8
1250 Hz 69.1
1600 Hz 67.3
2000 Hz 59.1
2500 Hz 55.5
3150 Hz 60.8
4000 Hz 66.0
5000 Hz 69.9
6300 Hz 75.8

Add RC 2 sides

TestID TL-93-223
STC 54

50 Hz 13.7
63 Hz 15.2
80 Hz 22.4
100 Hz 23.2
125 Hz 30.3
160 Hz 36.6
200 Hz 42.1
250 Hz 48.3
315 Hz 52.6
400 Hz 57.0
500 Hz 61.8
630 Hz 66.1
800 Hz 70.8
1000 Hz 74.2
1250 Hz 77.3
1600 Hz 76.7
2000 Hz 63.0
2500 Hz 57.6
3150 Hz 62.5
4000 Hz 69.0
5000 Hz 74.2
6300 Hz 79.4


I hope this clarifies things.

Sincerely,

Rod

they make zero clearance cans - ones that you can insulate tightly around - you have to use these can't if you are placing them inside of a box.

Hello Rod, thanks for the reply. Although I don't understand this...
"you have to use these can't ..."

Are you saying you HAVE to use "zero clearance" cans, but you CAN'T use them in a box??? And if you HAVE to use these in a studio, are these cans SEALED, and since they penetrate the cieling envelope, to what extent do they alter the TL rating of the ceiling leaf? Just curious how recessed cans are addressed by serious studio designers. Hmmm, maybe they DO NOT address them at all. Maybe they DON'T penetrate the ceiling period, huh???? Thats what I would have guessed. But of course, I'm not a serious studio designer. So what do I know. Ha!
fitZ

ps. If cans ARE used in pro studios, do you have a link to a detail showing this condition Rod? Thanks again