re: how small is a "small house" ?
19 jul 2003
pat meadows wrote:
>>as i recall, "frost protected warm foundations"
>>needn't be deeper than 16" anywhere in the us.
>i cannot believe this is correct. unless 'frost protected
>warm foundation' means something not obvious to me.
>what does it mean?
foamboard foundation wall insulation extends down at most 16" then outward
from the building for at most a few (4?) feet, with soil on top. dimensions
increase in colder climates (deeper and wider with more freezing hours per
year) and floor insulation (wider with more) and whether the building is
heated or not (wider if not.)
this is widely done in northern europe, and accepted by us codes. it works
by making frost travel sideways as well as downwards before it can freeze
the ground under the foundation. there's a free hud manual on the web.
the national homebuilder's association sells a paper copy for $25.
one variation would be a crawl space with a sealed skirt that might contain
cheap automatic foundation vents that open in summertime, with the house
supported/cantilevered by blocks on the ground (no digging :-) far enough
inside the skirt that the ground would never freeze under them. plastic or
rubber water bags in the crawl space might store rainwater, store heat,
treat sewage, and keep the house from blowing away. i've never seen this
done or documented. might be an interesting building code battle.