What is the best way to tape XPS seams in a basement installation? Also what is the best way to seal the bottom of the XPS to the concrete floor?
In Canada, Tuck tape is the standard. Tyvek is another popular sheathing tape. Sealing the bottom is not all that important if the concrete screws are holding it tight along the bottom. If you want, hand-held multi-purpose polyurethane spray foams do a good job.
Tuck Tape is one of several sheathing tapes
used to seal XPS boards.
I think the Tyvek is whats available here in the states. I caulked along the bottom with some sort of stuff..do not recall the name...the acoustical stuff they use on Holmes on Homes I was never able to find. I did half my basement in the xps. When my new heat pump died I had one register put in place (I need to get others added late). My basement used to get to 58 at its coldest. I did not see it get lower than 62 this past winter---and I still have nothing on the floor, nor have I drywalled everything. The XPS would appear to be a great investment.