[stevehull]

I too was first schooled (several decades ago) on the virtues of insulating the attic, walls and letting the sub-floor slide with minimal insulation. We have learned just how wrong that advice was . . . .

In particular, I also am a BIG supporter of slab insulation of the periphery - up the foundation and stem wall until you reach the level where the wall insulation exists. I saw, very clearly, just how much heat would "wick" out of a slab or concrete wall. One house in Michigan had bulbs sprouting in February right next to the concrete stem wall. The soil there never froze due to thermal wicking.

In particular, within ten feet of a corner, I double the insulation (to 2 inches of closed cell foam) in those areas. Where winter degree days F are > 6000, I suggest three inches of closed cell foam up the stem walls.

Yes, heat does rise, but moisture in crawl spaces, drafty conditions and convection down there just sucks heat out of the floor above. There are areas (heating dd < 1500) where some of this is not economical, but insulation is CHEAP to put in at the time of construction and labor intensive to put in later.

One trick I have found is to use 5/8" "R-max" 4x8 foam sheeting underneath floor attached with hangers or such to give about 12 inches of insulation space. Before decking the floor, I blow in about 8 inches of insulation. It doesn't have to be perfect and a bit of insulation leaks out between sheets.

If I were REALLY fastidious, I would seal each sheet with aluminized page to prevent this. I will have to play around with bubble foam insulation as some of the gap ideas are intriguing.

The difference in floor "foot comfort" with sub floor insulation is amazing. Having grown up on a frigid cold winter slab floor in New England, I HATE cold feet.

I still do feel that a greater R value should be in the attic vs. floor; perhaps 2:1 ratio, but I think we REALLY messed up by not encouraging more sub-slab insulation, below floor insulation and periphery insulation.

Steve