How to seal off and insulate a sloping, tall crawlspace?
I’m in Oakland, California. My 1-story house is built into the side of a hill. The crawlspace is tall enough for a person to stand in at the front and rises to the mud sill at the back of the house. The cripple wall is 4 ft tall at the front.
I want to build an unvented crawlspace to improve the air quality in the house. I will be installing poly sheeting and insulating the cripple wall and foundation as if it were a basement without a floor.
The problem is that the dirt is 2 ft below grade at the front of the house and floods when it rains. I don’t think a poly sheet is going to stop this from happening.
Should I back fill to exterior grade and call it good or install an interior french drain and sump pump? Both?
The foundation is also concrete-capped brick. It’s in good condition and I’m waiting to see if I will have to replace it due to seismic concerns. There may be some kind of sealing and insulation opportunity there if that has to happen. I’m not interested in the cost of building out a real basement or lifting the house for a second floor, but who knows maybe I’ll end up spending just as much doing this basic stuff!