"DAC" wrote in message
ps.com...

Something you might also consider is putting foam inside your footings
so it meets the foam under the concrete. That will keep the cold from
radiating into the concrete floor from the sides.


With respect, If the outside of the slab and footings are not properly
insulated, then insulating the inside of the footing does not insulate the
edge of the slab from the coldest exposure. If the outside of the slab and
footings are properly insulated (to an effective depth) then the effect of
insulating the inside of the footing will be minimal but will do little
harm, it should certainly be done if there is water under the slab or
footing.

By far the most important location to insulate properly is the outside of
the slab. This will also help to prevent frost from penetrating under the
slab in the event that there are periods of no heating in the slab.