I have a 1920s house with concrete foundation that had a semi-finished basement. After a recent 3-day rain storm, my basement flooded (about 1") due to hydrostatic pressure. It wasn't just my house — all the homes on my row had the same issue.
I removed the drywall and insulation from the finished portion of the basement. Some areas of black mold were found and I am working on getting that taken care.
I am looking at insulating the basement again because it gets cold down there and I am using it as an exercise/home theater area. So, do I need to insulate the entire basement or can I just insulate some of the walls like it was prior?
According to information from buildingscience.com, it is recommended I apply rigid foam insulation to my walls:
The best insulations to use are foam based and should allow the foundation wall assembly to dry inwards. The foam insulation layer should generally be vapor semi impermeable (greater than 0.1 perm), vapor semi permeable (greater than 1.0 perm) or vapor permeable (greater than 10 perm) (Lstiburek, 2004). The greater the permeance the greater the inward drying and therefore the lower the risk of excessive moisture accumulation.
Best Answer
Just insulating the ceiling will keep the ground-floor floors warmer, if you walk around barefoot, but won't save much energy (air-sealing is a better investment for that) or keep the basement any warmer.
If you want to improve the basement climate, any insulation of the walls will help retain a corresponding percentage of the energy you're losing. Air sealing helps a lot here too, as does an indirect-vented boiler or furnace (so you aren't pulling cold air into the basement to make up what's used for combustion).