"Sill Seal" used in studio construction?

Has anyone used the product "Sill Seal" in the construction of any of their studio walls? I was thinking of running Sill Seal under the wall plates on the floor, and on the the top between the ceiling to increase insolation. Much like the neoprene or rubber idea on floating floors. Reason is, my ceiling is only 7'2" tall, so I am crammed, with not much for options. Thanks for replies or ideas, J

J, love to comment (can you tell?) if I knew WTF you were referring to - it always helps if you can post a link or pic when asking about trade name stuff - it's a big world out there, and things every Aussie knows about I have no clue - things I consider "standard" , people in Reykjavik (sp?) never HEARD of - Love to see a link or pic, or at least a thorough description... Steve

I think the Dr. is talking about this stuff.

Its used under the base plate in a wall (particularly on exterior walls) to eliminate any air gaps between the base plate and the concrete foundation. I actually used 2 layers of it. It might aid in isolation. I dunno. It "squashes" down pretty flat once the wall is loaded though. Its primary purpose is to eliminate any possible space for air to leak out, making your HVAC more efficient. Here, its required by code. You can just make out a thin pink line in the photo. (I intend to caulk that seam too.) :wink:

Cool Michael, thanks - all that type of thing is CLOSED cell foam, which is what's needed for sealing and probably helps in de-coupling walls from floors. It wouldn't be worth ANYTHING for acoustic treatment, same as the "rigid FOAM" sold by Home Depot and others... Steve

Steve - the stuff is only 5 1/2" wide. How could it possibly be used in any way for acoustic treatment? I mean, I know its no good for that, but, can you get closed cell foam wider than 5 1/2"? I guess that's what I'm asking.... Just curious. But, so.... you think it would aid in isolation? Thats cool if it does, 'cause, umm.... I put it under the interior walls too. :)

Michael, I was kinda half-joking about the acoustical treatment comment, just noting the similarity of materials more than anything. About the only place I could think of that a person might consider using the Sill Seal stuff that way, would be as surround inside a double wall/double window (around the window) and that would be a BAD idea. You'd want something a lot more absorbent, like either OPEN cell foam, homosote, 703/705, etc - And yeah, bedding your walls with a couple layers of the stuff should work pretty well... Steve

i though that stuff was there to create a vapour barrier between the concrete floor and the timber frame. We run similar stuff under window sills for water barrier and where timber joins concrete. cheers john

Yeah, John it's good for that too. Closed cell - heat insulation, acoustic SEAL, vibration damping, vapor barrier Open cell - acoustic absorption, dish washing sponges :=)

Thanks for the replies guys. I guess what I'm trying to acheive is a barrier between the bottom plate of my wall, and the concrete floor to decrease sound transmission. I guess like a poor man's floating floor- exept the walls would float on a doubled layer of sill seal (or something else?). The problem is, my ceiling is so low (7'2") that I can't float the floor or hang the ceiling, so I figure I'm left with trying to make the walls and the ceiling "float" on something absorbant. If anyone has suggestions I'm all ears. Thanks, J

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 ? I know 7 foot ceilings is a tough one, but there are things than can help - it's just hard to figure out on verbal descriptions... Steve

Hello Steve, Dr.J. Just some minor things. (little time to go in-depth next week). Decoupling in the studio world must be one of the most abused and misunderstood words and/or concepts in acoustics. Look at: http://www.earsc.com/pdfs/engineering/i ... epaper.pdf At the bottom I entered one of there pictures (credit not mine, but E;A.R.'s) What you see at the resonance frequency is that the decoupler acts as an amplifier rather than an attenuator. In orther words doing decoupling wrong can introduce a problem rather than solving one. I've seen numerous messages in groups, where I'm sure that the posters were introducing a problem, which wasn't one before. So, or you calculate decoupling, understanding what is happening, which is related to load versus spring properties of the material, or you don't. So it's not the question, which is the perfect material (which indeed is an important parameter) but how to apply it in your specific circumstances. Therefor the excat load and properties of the material must be known. For linear springs (as helical springs) it's rather easy to check since there a linear relation between the compression of the spring and the resonance frequency. the formula: fo = 15.8 / sqrt (imprint of spring in mm). However synthetic materials react non-linear and must be checked. Basically if you just want to isolate your wall from the floor, someting as vilt, or low density open foam is OK, even when it' gets pressed together. As such you use it as damping (meanly influence on high frequencies). and as edge absorber (as an attenuating ventilation splitter silencer). Once you try to do it better, by using higher thicknesses hoping it will really decouple than it just becomes dangerous if applied wrongly. If you look at the picture you'll notice that it is in fact a vertical flipped isolation curve of a cavity wall, which in principle works exactly similar (air is a spring as well). You can interpret the 1 horizontal line as the mass-law, and the deviation versus this neutral line (this 1 equals 100% is no decoupling, no amplication = 10 log (1) = 0 dB) as the effect a cavity wall brings compared to the mass law. Note: this is not an accidental similarity. It explains the main physical basics of a cavity wall. So when you reverse it, one notice the nonchalance often decoupling is handled (more like if it feels soft and/or elastic it should be good). This is not caused by the users but by the companies selling this material as a side product, I assume often even unaware about the physics behind it. Doing decoupling wrong can be compared with building a cavity wall with 1/2" boards on each site with a cavity of only few mm (fractional inches) creating a dip in insulation at the mass-spring-mass resonance. And this dip can be interpreted as an amplification of the sound transmission compared to the same wall, with the same mass, build as a single leaf system without cavity. Kind regards Eric

One more thing, The shown material is polyethyleen foam which is indeed used for cheap floating floor systems (and thermal purposes of couse which is mean target). This material gets it resistance by the enclosed air bubles (Is closed cell foam). The material itself has no resistance. So it acts as the tires of a car. Under dynamic load this air will escape, just as the air of bycicle tires does. This is no material to use for demanding applications. Eric

Hi Eric - great post :) On the chart - what is the frequency ratio? If I understand correctly - this means that at some frequencies the isolation is not isolation at all - the product amplifies movement with rubber & silicone being particulary prone to this. In my situation - the 2 walls both sit on a common concrete slab. The outside wall does not have any isolation or sill seal under the wood footer. It's just caulked along the edge. For the inside wall what would you recommend to put under the footer 2by4?

Hello Andrew, I checked the thread, couldn't find your name. So I don't know your construction (maybe I missed somewhat, somewhere in another thread) I can only get the feel for something if I have a clear picture of the exact build up of a construction. If it's a room in a room, the outer shell is also part of the construction (even when seemingly nowhere in direct contact). If it is drywall ......, if it is ?????.... I can't try to list all possible occurences. So limit myself for now to the principle part. The frequency ratio is the frequency versus the resonance frequency here noted as 1 (reference). This resonance frequency is defined by the the (dynamic) load versus the (dynamic) stiffness of the spring. So this depends on the specifics of the application. Don't mind the names silicone or rubber. Meant is materials with low internal damping. E.g. for a helical or other steel spring this amplification is even worse. E.A.R. sets those materials versus one of their own products in this picture. One can easily recognize materials with high or low internal damping. Let some silicone dry and drop it on the floor: it bounces back = low internal damping = the energy is stored in the material and given back. Take plumbers mastic or children's clay, drop it on the floor and it drops dead = high internal damping = the energy is disipated in the material itself. In principle: The lower the internal damping of a spring the better the decoupling in the isolation area, but the higher the amplification at the resonance frequency. And vice versa. Gas or oil dampers on a car are used to damp the resonance frequency of the spring system, or your car should jump of the road. So this is a perfect balanced system between damping and spring system. But however perfect the gas or oil damper diminishes the decoupling of the spring system in the isolation area. However perfect the system is a compromize. Best regards Eric

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?

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

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.

"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

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

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.

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

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

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

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