next summer, i'm planning to seismically retrofit part of our house (the basement part for now). we have lots of cripple walls coming off our basement and those, i've learned, are usually the key failure point in an earthquake (assuming the house is bolted down to the foundation - which i question in ours...). we're just north of seattle and awaiting the big one.... rather than removing siding and putting plywood up on the outside, i think i'm going to tackle it from the inside since it offers a good number of benefits, not to mention that i wanted to redo the insulation anyway. my question is pertaining to the use of plywood or OSB to act as my new shear walls for the cripple walls. if i put it on the inside wall, my understanding is that they (especially the OSB) will act as a vapor barrier. one can read tons of articles about vapor barriers and get 10 different opinions, so i'm not sure if this thread will solve that issue. but, after installing the seismic anchors/brackets/etc, here's what i plan to do: 1. spray closed cell foam against concrete wall 2. insulate remaining wall cavity with roxul or fiberglass insulation 3. cover with plywood/OSB for shear walls 4. drywall 5. paint with latex paint i also plan to install 1" foam on the floor and 1/2" ply over the top of that before carpeting. from the few exposed areas of concrete floor i've seen in the basement, things seem very dry and well constructed. similarly, on the one wall where i used to have a downstairs fireplace, it appears the studs are dry and the current batt insulation looks okay (r-11, though installed poorly). this all makes me think the basement is performing reasonably well in its current setup. my concern isn't that i will not gain increased warmth/insulation after my project, but that i will inadvertently create a moisture problem since things will not get to breath in the same manner. that said, the basement is drywalled and painted now, so that's effectively a vapor barrier anyway. thoughts? thanks.