Which insulation should I use under my cottage?

denis maurier
Updated: May 4, 2021

my cottage is over a dirt floor, the foundation walls all in 2x6 and plywood, what type of insulation can i use on walls .  and to point out the walls are sitting on contrete blocks no footing

my plan is to add a 6mil barrier to floor, 

i eventually want to use in winter

thx  denis

Responses (3)

Mike Reynolds 3 years ago

Where are you located Denis? What you are talking about doing here with an exterior waterproof membrane on the outside of the plywood is going to be a vapor barrier and prevent walls from drying to the outside. That's a bad thing to do in a cold climate, that's why your climate zone is important. 

Blocks should not be on their side, that's not where their structural strength is, they should be upright with the holes at the top and bottom. I know this is a costly and labor intensive suggestion here, but ideally you would jack it up first and get the blocks on end the way they are supposed to be, that would also allow you to do a water proof membrane between the top of the blocks. 

The blocks are really porous, so I just needed to throw that out there. If they are sitting in wet ground, or water as you mention, the blocks will stay wet and in turn wet the sill plate of your framed wall. So if there is any way you can get some poly between the block and the wood that's a really good thing, even if its just prying it up a half inch at at time to slip a waterproof membrane of some kind in there.