What a great site! I have a owner-built log house, 30 yrs old, 16" concrete posts down 6' on 15' centers (so I was a recreation director, not a contractor). There are similar sized cedar posts (now rotting) located between the concrete (we were on a budget). I didn't leave enough crawl space under 30% of the house and I am concerned the insulation is lacking for various reasons and I can't reach it without raising the house or digging out. So, I thought I would pour a concrete skirting wall under the logs and around the house with vents, etc. and maybe put a small heater for winter (remember we are in the Rocky Mountains). My thoughts so far are to use styrofoam insulation as the concrete form on the inside (and leave it there) and wire a removal plywood form for the outside. Questions: - does the above form idea seem reasonable? - Will this method suffice to keep the floor warm? - How should I seal between concrete and sill log? - any other helpful hints? thanks for your feedback.