Rigid insulation over 1960 slab, heating cable, porcelain tiles, how?
delson
| Posted in General Questions on
I plan on installing electric in floor heating over an old concrete slab which likely has no barrier underneath.
location: Catskill region NY
size: about 900 sq ft
concerns;
negative hydrostatic pressure
insulate heating cable from slab
what type of insulation to use
how to adhere xps, eps, etc. type sheeting to slab
how to adhere tiles such insulation sheeting
cost of possible such sheeting, options in the us are few and costly
looking for out of the box creative ideas..
thank you
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Replies
Tile would need some sort of sub-flooring above the foam for it to be stiff enough to not crack. It can't be adhered directly to the foam board, which isn't stiff or hard enough to use as a tile backer (even on walls, let alone floors.) Foam board construction adhesive is the right stuff for making foam board stick to concrete, but if installing a subfloor, through-screwing the subfloor to the slab with masonry screws keeps it all in place.
If the soil under the slab is dry and well drained, digging-in 2.5 of EPS slab-edge insulation to a depth of 2 feet (if zone 5) or 4 feet (zone 6) would be enough to meet code, and the slab losses wouldn't necessarily be terrible. If it's wet clay under the slab it absolutely needs to be insulated above the slab.
There are multiple vendors of used or factory seconds foam board in NY selling at a fraction of box-store retail, many of whom advertise here:
https://catskills.craigslist.org/search/sss?query=rigid+insulation
https://albany.craigslist.org/search/sss?query=rigid+insulation
https://hudsonvalley.craigslist.org/search/sss?query=rigid+insulation
https://binghamton.craigslist.org/search/sss?query=rigid+insulation
https://utica.craigslist.org/search/sss?query=rigid+insulation