Subfloor adhesive VOC concerns
Hello.
I’ve been putting a lot of effort into using low Voc/no Voc products into my build. Today, there was some miscommunication and my builder used DAP subfloor and Deck adhesive instead of the adhesive I provided.
Here is the link to the product: https://www.grainger.com/product/DAP-Tan-28-oz-Subfloor-And-Deck-2KVJ8?functionCode=P2IDP2PCP
After looking at this product further, i realize it’s not sold in several states, and all sorts of toxic claims. Absolute disaster for me.
My question is, how long does this stuff take to offgas and is this something to be concerned about because it is under my plywood subfloor? My builder used two large 24 oz tubes on the ~200 sq foot space.
Thank you!
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Replies
Grey,
Unless you have a special medical condition, I wouldn't worry.
Your plywood subfloor is an air barrier. Most of this adhesive is on the exterior side of your air barrier. Moreover, you probably plan to install finish flooring on top of the subfloor. Many types of finish flooring are also air barriers.
Time is your friend. Let it cure. I have never heard a case of a homeowner complaining of odors or emissions from subfloor adhesive.
Grey Wolf,
For practical reasons subfloor adhesive is formulated to cure quickly and the off-gassing that occurs after that is minimal. If you are sensitive to VOCs and mold your best strategy is to ensure your finished home has good ventilation that can diminish the concentration of any contaminants to a level that is so small it doesn't affect you, and will keep moisture levels low.
Hi malcolm,
Doesn't it need air flow to off gas? With the adhesive sandwiched between the joists and subfloor, there is next to no air. I was concerned with this dap product because it's quite higher than most.
Jon, what would 60 extra days do? I'm not going to be moving in for five months already?
Grey Wolf,
Please be reassured that I am not dismissing the seriousness of your concerns. If you asked a similar question about flexible sealants or some solvent based finishes I would be suggesting a different solution.
It's important to distinguish between products that contain high levels of VOCs that off-gas quickly and pose a problem during installation (like most adhesives and many finishes), and those that have ingredients that will off-gass over time and can then affect the occupant.
Subfloor adhesives complete their hardening quite quickly and are then fairly inert. Like most glues they are designed to work between two materials and are not dependant on significant air flow to harden. They don't leave behind a reservoir of VOCs that is trapped must somehow dissipate over time.
Makes sense. What would you say is considered quickly? Are caulking and sealants finished off gassing after they harden? Also, can gas molecules/vocs permeate through plywood?
I will go ahead and contact the manufacturer as well, to see if they have more specific information on the product.
If you are worried about formaldehyde and aldehyde contaminates, consider using a product like Certainteed AirRenew. That's what I did.
Do they have any products for flooring?
Steve, how much difference did the AirRenew make? Night and day or subtle? Does it eat up all the new construction smells?
Also, how much price premium per sheet? I might go down this route too if it's not too expensive.
Anon3. My whole construction strategy was geared to creating a healthy and energy-efficient home. So I can't really say how much the specialty drywall contributed to those goals. I bought the product as a fail safe in case any VOCs slipped through and made it into the build process. As for cost, I never asked the contractor for comparative numbers. No doubt it was more than standard drywall.
> what would 60 extra days do? I'm not going to be moving in for five months already?
Then most of the floor adhesive vocs will be long gone. But other, later things might make it still worth it.
Hi Jon, how do you know this? Is this proven that sealants off gas in that time? Do you happen to have any sources (I believe you I'm just interested in looking into it further)
You can google "voc indoor decay" to find typical exponential decays on the order of 10x over a few months. But for proof in any specific case, I see no alternative to measuring it.
Some generic things to consider:
measuring voc level
running high ventilation rates for the first year
delaying move in by 60 days
Most of the new houses I've been to still smells after about a year. They generally lose that smell at year 2 or 3. Hardwood floors are the worst.
Steve, that's not encouraging... I guess I'll have to get my own quotes when the time comes.
Does anyone know how that 420 g/l VOC content compares to other products used in construction? It's an arbitrary number to me unless I can compare it to something.
Hi Martin. I am rather sensitive.
Do air barriers block voc emissions completely? Do you happen to know how long subfloor adhesives take to off gas in general?
I'm more just concerned that a mistake like this will become a problem once I move in. Being a very sensitive individual, I decided to build this to stay away from vocs and mold.
.
A low-VOC product often means it has less than 50 g/L VOC.
Here's a quick summary of paint VOC levels from Consumer Reports in 2008:
From looking at the safety data sheet for the adhesive you have, the VOC appear to be highly volatile solvents, such as toluene, that are quite bad to breath, but also evaporate very quickly. So I would expect that these would be completely gone within a few weeks. To be sure, you might want to ventilate the space under the subfloor, to help the vapors get out sooner. I'm not sure of enough details of the structure to know what in particular to recommend, but it might mean drilling some 1" holes somewhere, and sealing them back up with tape after a month or however long it takes for the smell to be gone.
Hi Charlie,
I was told the VOC's disappear as soon as the product hardens. Is this correct? I do not notice any smell anymore, but it is completely outside.
The subfloor is actually on a a trailer (it's a tiny house on wheels).
From bottom up
1) Metal bottom plate flashing (seams and corners not sealed for any drainage/moisture escape)
2) Roxul batts in between steel joists
3) Intello plus vapor retarder
4) Plywood subfloor (dap adhesive in between intello plus and subfloor)
So there really is no where to poke holes unless I directly in the plywood (and then I would risk puncturing the vapor retarder/air barrier).