Acoustic sealant: Best types to try?
My builder is recommending we seal between the sill plate and concrete with a silicon sealant on the outside of the sill plate, however I know most people here recommend acoustic sealant for that job.
I want to test a few tubes of acoustic sealant to see what’s worth paying the extra $. It would be nice if I could find something in my local Home Depot but alas it seems I have to order it. I’m hoping to find one solution I can use on the outside of the sill plate and on the inside on my sheet rock. What ones should I try?
Brands I’ve found online:
Green Glue $0.61 per oz
Liquid Nails $0.21 per oz
OSI SC-175 $.036 per oz
Big Stretch Sashco Caulk $0.51 per oz
Anything else I should be considering?
Steve
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Well, everyone likes tremco and its great but messy.
I have used a couple hundred tubes of USG Acoustical and USG firecode acoustical recently and i like them. Im somewhat allergic to many caulks and the usg is wonderful, no reaction.
The usg stuff has the unique property of "sucking into" joints after it sits 24 hours or so.
Price point is great too. Less than $5/29oz
Just read the USG label, and it says not to use it in moist environments. I wonder if you have any experience with it working well (or poorly) in places like sealing a poly sill-sealer to the mud sill and to the foundation? Any mold development over time, or issues in cold weather?
The OSI SC175 dries like regular painters caulk, it doesn't stay tacky like Tremco does. Price point its good but not something I'd use on my House.
While some people recommend acoustic caulk for such air sealing, the ones who really understand the product (the manufacturers) often don't. Would be interesting to ask someone like Tremco (they make all types) about this. My guess: no rated movement capability means it may get pushed out, leaving a leak.
Be careful even with a more general purpose caulk like Big Stretch Sashco Caulk. It claims 500% stretch, but then gets a low 25% in the ASTM C719 test. And doesn't even list D412 performance. Compare to Tremco Dymonic 100 or Spectrem 1 (+100/-50% on C719).
I contacted my Tremco rep to ask what he'd recommend for sealing plates etc. Dymonic 100 or Tremsil 400 were his recommendations because of their high resistance to compression and expansion per ASTM C719, along with their adhesion to substrates. He went on to check with the technical department. They said Tremco acoustical would only be preferred for connections to poly because being bituminous in nature meant better adhesion to poly (poly being oil based).
I can get Dymonic 100 for CAD$15 per 20oz, plus it has low VOC content. Seems like a good, budget friendlier version of Contega HF.
The reason for using acoustical sealant often seems to be that it is non hardening, therefore tolerant to movement. But I've seen nothing to support non hardening being better than high tolerance to compression/expansion, and the manufacturer recommendation seems to support this.
Alex,
I've never understood the non-hardening vs flexible argument either. Anything that successfully replaces acoustical sealant has my vote. I hate working with it.
Edit: Thinking about it again, the benefit of something like acoustical sealant between poly and framing is you can run a bead, staple up the poly, and leave things until the boarders show up. With a flexible caulk you would have to roll it flat to make sure it didn't harden as a bead leaving bumps under the poly.
Steve,
Acoustical sealant is widely used to seal poly to framing - and it works great - but you only want to use it in situations like that where you are sandwiching it between two materials, not as a general air-sealant. It is designed never to harden and remains sticky, meaning it picks up debris during construction, and if you touch it it gets everywhere ruining finished materials.
For the same reasons don't consider Green glue. Big Stretch works very well. Builders on GBA also often recommend Pro Clima Contega HF.
Malcolm, I'm not sure if you are aware, but Green Glue makes a Noiseproofing Sealant in addition to the regular Compound for between drywall sheets. The Sealant is nice stuff as far as I can tell; it dries to the touch, remains flexible, and has little odor compared to Tremco.
Unless I stumble across better products, or better value products, my personal approach will be to use Tremco for everything outside of my vapor retarder (ie everywhere outside of the indoor air) and Green Glue Sealant inside. Tremco seems to do an incredible job at sealing between materials and is very affordable, it's just messy as heck and stinks for a long time after installation. GG Sealant is advertised as "Low VOC", doesn't stink, and is much more like traditional caulk to use. It's 3X the cost of Tremco, though, so it will only be used inside.
https://www.greengluecompany.com/products/noiseproofing-sealant
Should most of these products be used on the inside or can they be used on the outside too? I have the usual applications for an air tight home such as sealing between the sill plate and the concrete foundation wall, sealing between the sill plates, sealing the bottom edge of the sheathing to the sill plate, sealing dry wall to the inside floor.
The Pro Clima Contega HF is an expensive solution at $15.00 for 10 oz but if that's what it takes then that's what I should use. I'm having trouble locating the USG Acoustical Sealant locally.
I'm surprised there is not a universal solution that people agree on. I'm sure my builder just wants to use a 50 year latex caulk.
Steve
Everyone has products that they like or dislike based on their own preferences and experiences. There is almost never a single, universal solution that everyone likes for a particular problem.
I would not use green glue as a sealant. Green glue is a specialized sound deadening product, it’s not even really an “acoustical sealant” the way the others are. Green glue isn’t intended for sealing, its intended to make a viscous layer between sheets of drywall to reduce sound transmission.
I’ve never tried using acoustical caulk on the exterior. My concern has always been that freeze/thaw thermal cycling may be a problem for the product. If you can find an acoustic caulk that is rated down to below freezing temperatures than you may be ok though.
Bill
Bill, GG makes a Noiseproofing Sealant as well as their regular Compound:
https://www.greengluecompany.com/products/noiseproofing-sealant
From their sire:
"Green Glue Noiseproofing Sealant is used to fill gaps and joints where the wall meets the floor or ceiling, and where two walls meet. It can also be used around outlet and switch boxes. Easy to install and paintable once it dries completely (48 hours)..."
I'm big on polyurethane sealants. They're inherently a glue and the hybrid tube stuff stretches very well.
I really like Tremco's dymonic 100. I used it for all my frame sealing including sill plates and backdammed my windows with it. I also have a polyurethane roof membrane so I used it for sealing transitions and roof penetrations, including a few flexible electrical conduits, the sealant just moves around with the conduit when I move it around. All my Hardie panel siding I caulked the top with this stuff too, so full exposure to UV, rain and freeze/thaw cycles, after a couple years its still adhered and looking well. We'll see how it goes in a few years.
In my own personal testing, I made a long thick bead on a bit of polysheet and let it cure, after pulling it off it feels quite like a bungee cord.
However, I don't know what you guys have down there in the states, up here in Toronto it's $1.2 per ounce from the local hardware store and so is big stretch. I wish I had bought cases of dymonic from the factory at the start of the build.
Jamie, what was the polyurethane roof membrane that you've used?
Hi Vlad,
I was looking at Tremco's Alphaguard MT & PUMA at the time. In the end, I went with a smaller company with a similar product called kemforte.
https://www.kemforte.com/
Thanks Jamie, I'll check them out.
When taking apart walls due to issues from past builders, I've seen newer homes with treated wall plates at foundation with silicone that has shrunk? peeled away so something is going on that I don't like to see. I really like Contega HF but will have to see my own work in years to come to check in on it.
> ... polyurethane sealants. They're inherently a glue ...
Where you have plenty of contact area, this is a good way to prevent a crack from cycling between 0" and 1/16" (which would otherwise need a filet+bond-breaker) .
> silicone that has shrunk? peeled away
Good gaskets (like EPDM) don't suffer from this problem.
In our industry it is not uncommon for each of these materials to get mixed together, by terminology and function/use:
1. liquid sealant
2. mastic
3. liquid adhesive
In general, liquid sealant is installed as a bead ("hourglass" shape in a horizontal joint with backer rod or "quarter-round shape with a bond break tape); mastic is applied as a coating left exposed to the air; and adhesive is applied as a bead that gets compressed between materials.
And yet, we use "caulk" (liquid sealants) compressed as an adhesive as we installed flanged windows, we smear sealants left exposed like a mastic; and we move from acrylic to silicone to polyurethane liquid sealants based on price rather than properties.
Sometimes these substitutions work (anecdotally, time and again, I hear of long-term success with Tremco acoustical sealant used as a mastic to seal for air and water) and sometimes movement of one or both substrates is too much for the sticky stuff to span over time.
Bottom line: take a look at this series of blogs I wrote (www.buildinggreen.com/stickybusiness) and don't use sticky stuff in ways NOT supported by manufacturer installation directions, or you do so at your own risk. Some companies have done their own longterm testing of sticky stuff (Walsh Construction of Seattle, for example) to combine manufacturer directions/uses with real-world testing.
Peter
Green Glue comes in two flavors. Green Glue Compound is the stuff you put between two layers of drywall for soundproofing. Green Glue Sealant is used to seal edges and gaps. It feels like acrylic painters caulk while being installed. It shrinks somewhat while drying, and when dry to the touch remains soft. I had to remove a wood member sealed with the sealant and the bead stretched like cheese on a pizza. It had well over 1000% stretch.
I got mine at Menards at a cost of 29¢/oz. They also sell the Green Glue Compound at the bargain price of 52¢/oz.
Douglas Higden
We used a bead of Contega HF combined with an EPDM gasket under our mudsills. I then went back and ran a bead of sealant on the outside edge connecting the sill plate, gasket, and the top of the foundation. In effect, it gave us three chances to air seal this gap between the mudsill and the concrete.
I have photos and details here: https://kimchiandkraut.net/2017/01/25/framing/
You would think the EPDM gasket would be enough on its own, but there's usually enough imperfections in the concrete to allow some gaps to show up. Having said that, I would definitely use the EPDM gaskets again --- they were easy to use and install, they act as a capillary break, and they did most of the air sealing for us.
I've also had luck with various products ordered from http://www.greenbuildingsupply.com
I used their ChemLink M-1 sealant in various spots on the interior and exterior and it's holding up well. It's low VOC and cleans up with rubbing alcohol.
Has anyone used DAP Mono Acoustic Sealant? Thoughts as to being better or worse than Tremco?
I’m not sure if it’s bituminous (claims synthetic butyl rubber)? The SDS says it contains Trimethylbenzene and Stoddard Solvent, but I’m no chemist:
https://canada.dap.com/media/188616/00042435604english.pdf
I picked up a few cases on clearance for about $2.50/29oz tube, but I’ve never tried it before. Just couldn’t pass up the deal. Here’s the product page:
https://canada.dap.com/dap-products-ph/mono-acoustical-sealant/
“Provides an effective adhesive seal for air and vapour barriers. MONO® Acoustical Sealant meets CAN/CGSB 19.21 M87 specifications.”
What products would work best for filling/sealing a fairly decently large gap under the drywall where it meets the plate between two bedrooms? My house has not so level floors, and when I re-drywalled, the drywallers put up the drywall level, which leaves a decent gap between the subfloor and plate. I was thinking of filling it with an acoustical caulking of some sort that would limit air/sound migration between the two rooms the best that I can.
Caveat, I might add an additional 7/16" OSB underlayment on top of the subfloor to even things out throughout the house before adding LVP flooring, so I'm not sure if I should seal before or after that underlayment goes down.