EPS on basement wall -- vapor barrier advisable?
I came across some unfaced 2" EPS for cheap, so I want to use it to insulate my basement walls. I don't know its density but I assume it's whatever is most common. At 4" total, this puts it at about 2-2.5 perms. The perfectionist in me wants to put poly sheet behind it to have a full vapor barrier, but how much difference will that realistically make in the dryness of the basement? It seems like gluing the poly to the wall, and the EPS to the poly would be awkward, and I don't really want to sink anchors into the concrete. I already have a bunch of poly just sitting around.
It's a typical 1950 concrete basement in the Pacific Northwest. It's currently not conditioned and ranges from about 50F/50RH in the depths of winter to about 70F/70RH in the summer. 3/4 of the rim joist is still not air sealed (though it will be eventually), the floor is part unfinished and part tile. The walls are Drylok'd.
Posted May 15, 2014 6:55 PM ET
Edited May 15, 2014 6:59 PM ET
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