We just moved into a home late last fall. The home was built in 1978 part on slab part on crawl. A master addition was added in 1996. This is on a crawl space (cinder block). Myself nor the inspector caught the problem I found while trying to figure out why the master room / floor was cold. The builder, I assume to match up the floors between rooms, put the rim joist and sill plate under grade. That’s right both under ground. They are not rotting yet but are both very wet (I am not sure if he even used pressure treated wood). What should I do. My first thought is to remove the soil around the additions three sides, somehow dry out the wood then cover/coat it with a water proof material (don’t know what). Then put in drain tile and fill it back in with soil. Does anyone have any ideas and or material suggestions. As for the original issue of cold floor, the plywood subfloor looked OK (not wet or rotted) when we were putting hardwood down in that room. Could the subfloor that is behind the vinyl siding be getting air in that way? Please help. Thanks, Ted