[Greenbuilding] ***SPAM*** Insulating Joists in a Pier Foundation

[Lynelle Hamilton]

I am so glad that this list is still active!

My issue is somewhat similar to Reuben's.  I bought a home in 
Bracebridge ON (just north of the 45th parallel). The house is on piers 
that go to bedrock.  The slope of the land goes from 1' above grade to 
about 4'. The majority is at 3-4 feet in height. Terrain under the house 
is mostly rock, with some sandy loam. Sides are skirted and it's 
unheated. House is 20'x'40' approx and it's a full-time residence.

The house will have an addition in the spring, but the bulk of the 
existing structure will remain, as it's pretty well built.

My issues:

I'm seeking advice on insulating the underside of the main level. It's 
currently open, with Rockwool is between the joists, but they are 
otherwise exposed (underside of main level floor). I want to upgrade the 
insulation, so am thinking about using ISO or similar rigid board to 
span the joists. Ideally, I'd like something to allow vapour to flow 
out, block vapour coming in  and also provide a thermal break for the 
joists.  A neighbour raves about IKO Enerfoil sheathing, but I suspect 
it will not act as a vapour barrier in the manner I want.  Any 
suggestions are appreciated.

My second question is related. Is 6mil poly sufficient to lay on the 
exposed ground to avert moisture from the earth? Is there a better 
option (that's affordable)?


Many thanks!




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