Q&A: A Forum for Green Building Experts and Beginners

I previously had asked about the potential of constructing a rudimentary geothermal basement by purposefully NOT insulating the masonry walls of a basement. Martin pointed out that the ground temps in NY/NJ/CT in winter at the surface are freezing and not until something like 48 inches are they above freezing, say around 40 to 45 degrees? Thus making it clear the walls should be insulated. But what about the the floor slab? Assuming a depth of say 9 feet at the slab's underside, would this not be a constant 55 degrees or so? Thus be warming in winter and cooling in summer?

Is there a product that is safe to use on ceramic tile on the walls in the shower on a daily basis after taking showers?

I am finishing our 800 sq.ft. basement in Portland, OR (zone 4c). I am planning to lay a combination of carpet and linoleum and want to reduce the chances of mold from moisture that might seep up through the concrete slab, which varies in thickness from 2" - 4" in some spots. I have noticed a couple 6" diameter spots on the slab that seem moist during the rainy season, but no pooling of water.

Can the Dow Powerhouse Solar Shingle be safely installed on an unvented cathedral ceiling/roof which is insulated below the deck with impermeable closed cell insulation. will this Dow system trap moisture and condensation below it? What about the Certainteed Solar system which is installed directly on the roofing deck? For solar PV systems with modules raised off the roofing deck, what is the long term effect of shading, moisture and fungus on these shingles? Do these shingles below the raised solar PV module have to be replaced before the life expectancy of the solar PV system?