Quote:
Originally Posted by S-F
Any moisture will make the subfloor change shape. Usually this isn't a problem because people put it on regularly spaced joists and fasten them securely. When moisture levels change the joists and the subfloor both change shape. Just floating it over masonry provides not reliable means of fastening it. This is fine if you first fasten the bottom plates (pressure treated) to the masonry and then "float" the foam and subfloor between the walls leaving a 1/4" gap to account for expansion and contraction. My floor bowed and I used Advantech which is waxed in some way to resist moisture, so I can't imagine what regular subfloor would do. I ended up buzzing grooves in my floor to relieve the pressure. If I had to do this again I would fasten the walls to the slab with a powder nailer. I don't think it's a good idea to put the top plates on foam which is on something like DryCore or anything like that. It won't be able to support weight and the wall will sag eventually. Also you'd have to seal the foam to the foundation walls with something that won't dry up and crack when the foam moves (no product I know of. Maybe a Siga tape?) or else there's not point in the insulation board.
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The installation guide for DeltaFloors does say you can put no-load bearing walls on-top of it. I still plan on pining it to the floor (tapcon) and securing it to joists above. The wall itself won't weight a lot as its just 2' o/c 2x4s, fibreglass, and drywall.
I was planning on using a combination of PL300, expanding foam (great stuff), and tyvek tape to seal the floor to wall XPS boards.
The reason why I don't want the wall directly on the floor as it will defeat the purpose of the delta flooring by damming up any water seepage.
I plan on using the following detail for the floor on top of the delta floor. Things will be fastened. I'm hoping for very little moisture will the membrane and foam barriers.
