Sealing rigid foam on walls
We are finally starting to put 2″ XPS boards on the concrete walls of our basement. We are building a home and are DIYing this project to save a little bit of money. We plan to use PL300 to adhere the boards to the all and will be using tongue and groove boards. We plan to stud in the boards as well with 2×4’s (plate on concrete floor will be pressure treated and have foam sill plate under it). We are trying to avoid the use of spray foam if possible, but will use if it is much better. What do you recommend to seal the joints and the bottom of the board with (where it meets the concrete floor). We really want to use the least toxic products we can as our daughter is chemically sensitive. Specific product brands/names are helpful. We also have some PVC pipes running up the wall from the plumbing that has been done. Is there a way to insulate around these pipes (they are up against the wall unfortunately) or should we pay to move them? Thank you!!!! Your advice is greatly appreciated!!!!
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Carolyn,
If you are looking for a low-VOC caulk or sealant, you can choose from at least five such products listed in the GBA Product Guide. Here are some links:
Chem-Calk 2000
EcoGlue Extreme
Greenlink and ChemLink
Sherwin-Williams Caulks
Smart Zero-VOC 1408-1-61 Elastomeric Caulk
Carolyn,
If you prefer to use a tape, I would advise that you use a high-quality European tape like Siga Wigluv. I have never heard any odor complaints about Siga Wigluv.
My favorite caulk for that kind of application is Contega HF, imported by 475 building products. It's very low toxicity. It's does have VOCs, but those are entirely from the ethanol solvent used, so unless your daughter's chemical sensitivity includes needing to leave the room whenever alcoholic beverages are served, it is fine. (And I don't say that entirely in jest--I realize that being near alcoholic beverages is a problem for some people. But we have a good basis for confidence that the health risks from breathing a small amount of the vapor are very small.)
Thank you! Do you think it would be sufficient to caulk around the PVC pipe or will that compromise the insulation value and moisture barrier to much? Also is using caulk and tape together overkill?
With the pipe against the concrete, the easiest would be to use one-part spray foam to fill the space between the round pipe and the square edge of the insulation. If you buy thick pipe insulation, e.g. 1" thick wall, you can cut it down with a long-blade utility knife to get a square edge to go against the square edge of the foam and against the wall. Filling it with caulk would be a lot of caulk and kind of expensive. You could also leave open space there.
As far as the performance of those options, it depends at least on what's in the pipes and whether there is exterior insulation on the wall.