Harold & Susan Vordos wrote:

While you're hanging out, check this link. http://rastra.com/

It's a leave-in-place foam/cement block that is almost unique ( a couple of
copycat blocks have appeared recently). Unlike any other foam block, this
one has a 4 hour fire rating and has a very high R value, something like an
R30.

Interesting stuff. The one I posted about creates a five layer
structu Exterior finsh(I used stucco), foam, reinforced concrete,
foam, interior finish. The foam layers are about 2.5" thick. One
significant factor here is that the concrete is insulated form the
outside temperature and has a HUGE thermal mass. In consequence it
takes a long time for the shopt temperature to change. I light the
heater pilot in the fall and shut it down in the spring. The other day
a switch on the thermostat failed so the heater didn't come on anytime
between about 4pm one day until about 10am the next. Shop temperature
dropped from 70F to 55F in that time. Overnight low was about -5C
(23F).

Ted