"Sill Seal" used in studio construction?

AndrewMc · Post by **AndrewMc** » Fri Jun 20, 2003 6:03 am

Hi Eric - thanks for the response.

My wall construction isn't in this thread but I've detailed it below. I've had a lot of very valuable help from John on the construction.

This sill seal thread is timely for me because I will be constructing the internal wall soon & was wondering if I should put some kind of isolation under the 2nd wall.

The outside wall is OSB on 2x4 studs (with polystyrene foam on the outside - just for thermal benefit & then siding on that). The external wall studs are all caulked & then between the studs is 2 layers of heavy mineral loaded roofing felt stapled between the studs & then sealed all the way around. Then 2" of dense insulation. No drywall on the inside of the internal wall.

Then 4" air gap then 2nd internal wall - using Johns inside out design. Pink fiberglass glued to 3 layers of 5/8" drywall - leaving the exposed studs on the inside of the room to accept treatment.

Ceiling 2 layers of 5/8" drywall on Res-channel. The internal wall runs upto the ceiling & caulked.

The internal wall is not built yet - but will need to decide what isolation to put under it. I was wondering if it's really worth worrying about that - maybe just caulk under the wall & sit directly on the slab?

Eric_Desart · Post by **Eric_Desart** » Fri Jun 20, 2003 8:02 am

Hello Andrew,

You must excuse me. I'm Dutch and often have trouble understanding notions which are clear to others.

So I should like John or Steve to help out here.

I don't think I understand completely. The inside out design of John, I must still learn what this means.

I get the impression that:
a) your outside panel is rather stiff OSB-polystyrene- ?? sandwich.
b) Is the felt roofing free hanging between the studs?
c) The new wall creates this a triple leaf (double cavity) system?

Since John suggested the construction maybe he or Steve can pick in here??
Not that I don't want to help, just that I don't feel the construction (my limited English doesn't help). With feeling I really mean feeling. If I understand a construction with my brain, it goes to my belly (I feel the construction) and my automatic pilot takes over.

Best regards
Eric

AndrewMc · Post by **AndrewMc** » Fri Jun 20, 2003 8:19 am

Hi,

The outside is OSB with polystyrene on the outside - this has no acoustical value, it's just thermal & is under the siding. The roofing felt is stapled between the studs on the inside & sealed, so it's airtight - but it does have movement (ie it's not glued). I figured with this it would benefit because it's very heavy (2 layers is about the same as mass loaded vinyl).

There is only 1 cavity / 2 leaves. The external wall has no drywall on the inside face. The next wall is inside out. This is basically where the wall has 1 mass layer but the open studs face the inside of the room.

Here is a drawing of the final wall design I settled on. It shows Johns inside out wall.

Dr. J · Post by **Dr. J** » Fri Jun 20, 2003 8:50 am

"J, in which direction do you need the MOST Transmission Loss? And what's your ceiling like? Do you have any drawings posted that I've missed ? "

Well Steve, I haven't posted any pics yet - but I will tonight.

Basically my main concern is transmitting sound up
through my ceiling or vise versa. My walls are concrete on
3 sides of my live room, and the 4th wall (contol room)
will be double walled & stagger studded. I am framing all the
walls and then drywalling them all.

If you have any suggestion as to how to construct my ceiling
since its so low at 7', I'd appreciate it too.

Thanks for the info,
J

Post by **John Sayers** » Fri Jun 20, 2003 9:23 am

Yes - you've drawn it correctly Andrew. The three layer will be hard to put up as it will be heavy - Ask Luis.

Eric - the reversed wall system is a space saver system for small rooms. Basically the inner wall is reversed so the dywall is on the outside so the cavity can be used for internal treatment.

If you look at Left Bank at this site : http://johnlsayers.com/Studio/index.htm
you can see the construction in action.

cheers
john

knightfly · Post by **knightfly** » Fri Jun 20, 2003 10:41 am

J, looks like we've got a minor "thread hijack" going here, but it's all good - for your ceiling, go here

http://www.saecollege.de/reference_mate ... 0Chart.htm

and scroll down to the bottom - note that STC ratings change with upper floor treatment as well, but for minimum space that's what I'd suggest.

Deeper joists will help the STC, but the RC will improve things more than any other 1/2" layer I'm aware of (unless they make Sheet Blok in 1/2" thickness, and you could actually AFFORD it :=)

Kineticsnoise.com (and others, I'm sure) make a series of low/high frequency isolators that can be attached to the SIDES of floor joists and a T-Bar ceiling grid hung from them, but that would take 2-3 more precious inches from your already "vertically challenged" space and it's not a cheap way to go either.

For walls, your comment about "the 4th wall (contol room)
will be double walled & stagger studded" - isn't real clear without pictures. Were you referring to A. B. C. or possibly D, or something else entirely? You will note from the STC charts at the above link, that there are better walls to be built in the same space - you commented earlier that you were concerned with maximum sound proofing, if I remember correctly.

knightfly · Post by **knightfly** » Fri Jun 20, 2003 12:11 pm

J, I was just looking over your earlier drawings on the Design forum - are you still building in a garage? If so, what's ABOVE your studio, is this a free-standing garage or is there living space over it? (I'm hoping I'm wrong, and that the space above you is just attic, but somehow from your comments I doubt it...) Steve

Eric_Desart · Post by **Eric_Desart** » Sat Jun 21, 2003 10:23 pm

Hello Andrew,

Sorry I forgot to check this thread again.
Thanks for picture wall composition and John for explenation.

Still find it not clear. Not the picture. This is very clear.

Decoupling the wall is only sensible if the coupling is the weakest sound path.

So that's not only depending on the floor, but also edges, ceiling and whatever.
So I'm not that sure this is your weakest path.

In general:
The internal damping of a drywall system is rather good.
Problems of coupling you find mostly rizing towards higher frequencies.
That's why RC has so much impact on a wooden stut structure, since STC is strongly defined by mid and highs.
The impact in the low frequencies is much less defined by this coupling (for drywall systems). And it are the low frequencies defining music insulation.

So my answer: I'm not sure before having a complete picture and feel for the insulation you need and an overview of the flanking noise limiting this insulation. Improving the NOT-Weakest path has little of no influence.

Important is that if you decouple that you do it right, or you can have the reverse effect (introducing a problem which doesn't exist without).

Typical materials (but their are others) of foam (elastomer) and coarck agglomerates are:

E.A.R. products (elastomer foams)
SYLOMER (elastomer foams)
CDM (hybrids between coark and elastomer foam).

To be avoided as hell if you don't know how to calculate such materials in function of load and deflection (compensated by deformation).
Plain EPDM, PVC, MASS LOADED VYNIL, Rubber etc sheets.

Reason:
The first product series are compressable (dynamic styfness). So they can be used in large surfaces still acting as a spring)

The second series has a dynamic styfness high as hell, but work on deformation (sideways expansion) in order to act as a spring.
Rubber silencers are designed on deformation by compression. If you should prevent this sideways expansion they shouldn't work anymore.
So with unprofiled materials in larger surfaces this sideways expansion becomes insignificant, making them bad as decoupling however soft they feel when pressing your finger in them.

I saw John (in other message) using small pieces of rubber. That's OK if the deflection compensated by this sideways expansion is correct.

Best regards
Eric

Eric_Desart · Post by **Eric_Desart** » Sat Jun 21, 2003 10:32 pm

Just a comment to the STC chart on the SAE site.

STC is a bad parameter for music. Still think that SAE should now that and explain this on their site.

In my Acoustic Selector Excel file, almost ALL Boral drywalls are included with lots of different single number insulation ratings as STC, MTC, OITC, Speech, Music etc.

Is in fact meant as educational file in function of getting the feel for the importance of the TL spectra of a wall versus several weightings.
One can alter TL values in any spectrum and check the effect on the overal TL value in function of those weightings.

Kind regards
Eric

giles117 · Post by **giles117** » Sat Jun 28, 2003 4:29 pm

I am using the pick stuff as merely an isolator (poor mans float as well)

I am encouraged by what I have felt thus far. I will send new pics as things go along. Now that I figured out how to grab stills from by DV cam.

Bryan Giles