I live in Rhode Island and am in the process of finishing my basement. Based upon a wealth of advice I have have reading, I was planning on insulating the full wall (top to bottom) before applying the sheetrock, etc. However, I did read one source (Time Life book) which says I should only insulate from the top down to no more than 2 feet below grade. The argument is that unless my drainage on the outside of the foundation wall is very good, water may seep down there on the outside of the foundation, freeze, and crack the foundation. Hence, if you don't insulate down there, I guess you frevent this freezing from occuring.

Any reccommendations? My drainage around the house seems to be fine. Do I insulate the whole basement wall or just the top portion above the grade minus 2 feet line?

 

Go to www.doityourself.com/basement for helpful info re: insulation and other basement finishing issues.

 

Hello Kochrm

Lets start at looking at gound heat loss & frost penetration. You should make yourself aware of the frost line in the area where you live. This is the level of frost penetration in the ground. The ground, like every thing else freezes due to heat loss. The level of frost penetration varies with latitude & climate zones. Below the frost line the ground temperature remains fairly constant at about 40*F. Lets say the frost line in your area is two ft. below grade. This two feet of frozen soil contacts your foundation and allows significant heat loss through the concrete. To guard against this heat drain and conserve energy dollars insulation is applied. Your foundation should have been damproofed, and backfilled with granular soil, so water seepage should be retarded. Below the frost line the ground remains unfrozen, & so does water. Therefore there will be no danger of the problem you described. Code requirements (my location) call for insulation to or slightly below the frost line only. However full wall insulation is prefered for a more comfortable living space. If you are using batt insulation, leave the insulation 6" off the floor in case of minor flooding. As long as this area is below the frost line heat loss will be minimal.

 

You can go to www.owenscorning.com to learn more about residential insulation.