[AT] OT - Wooden foundation vs Concrete?

[Alan Nadeau]

There was one building done here on a wood foundation back in the late 
1970s.  I was working in the foundation business at that time but wasn't 
involved in the project.

The building was a "raised ranch" which has housed medical and real estate 
offices since then.  It's still standing and doesn't look any the worse for 
wear.  I'm pretty sure they poured a concrete footing to build the wood 
walls on.

I'm not sure what was done to keep water out but I think it was as someone 
has already described, multiple layers of plastic film over the plywood 
sheathing.  On this one they covered the plastic with foam board insulation 
and stucco to well below grade so there was no chance of sunlight getting to 
the plastic film.

Seems like they got the wood walls up and the deck on then poured the 
basement floor inside the wood foundation walls before they backfilled. 
That eliminated any chance of the walls ever pushing in from the backfill 
load.

Soil condition is very good draining sand, the water table is deep enough 
that you can dig 10-12 feet before you hit water so there isn't a water 
problem at the elevation of the footings.

The concept never took off around here.  That may be attributed to 
conservative thinking, which abounds in this area, "We didn't do it that way 
50 years ago".  One benefit is that the resulting basement is easy to 
insulate/plumb/wire as it can be done just like the upper levels.  I'm not 
sure what the $$ benefits would be given the cost of PT lumber.