Finished basement: insulate walls or not?

I bought my house with a very nice finished basement. However, after a few months and a lot of rain I noticed that the basement was very damp and green mold started growing on the walls.

I called a basement waterproofing company that found that the french drain system I had was useless: basically a trench filled with crashed stone and no pipe inside. Another issue that they pointed was that I had insulation between the foundation walls and the drywall that was touching the foundation walls and creating a wet envelope for the basement.

I am in the process of redoing the french drain system and removing the old wet/moldy insulation. The question now is: should I put new insulation? In some locations the drywall is very close to the foundation wall and I am not sure that I could fit blanket insulation without it touching the foundation walls again.

Thanks!

 

If the basement is below grade, insulation is redundant as the walls will always be the same temperature (varying little) year around, thus geothermally correct. Basement walls are generally build at least 1" away from the exterior walls. If insulation is used it is kept away from the walls to allow for air circulation and dissipation of the moisture. You seem to have other problems with the french drain which you are correcting. Basically keep your insulation on the walk out part off the outer walls.

 

It depends on what you are planning to use the space for. Our basement (which is a "living space" where we spend a lot of time) has painted concrete walls, and while it makes it cooler (not cold) in the winter, it also stays cool in the summer when you want it to. As long as you aren't touching the walls and have the basement heated anyway, I'd say you could easily paint the walls and be happy. We're perfectly happy with there not being drywall to rip out on the off chance that the basement floods, and the paint makes it look nice. If you leave the walls concrete though, be prepared to purchase either some inexpensive carpet remnants or rugs to cut down on the echo. That way if the basement does happen to flood you can try to salvage the carpet/rugs...or not. We found some carpet that was being ripped out after a year because the homeowner changed her mind about having beige carpet--we just unrolled it in the basement and it eliminated the echoes and looks really nice. You might find something similar on CL or Free/CheapCycle.

Note: Concrete takes paint colors differently than drywall--so be aware of that when you go to paint in colors other than white. There may be a significant difference....then again, there may not be, depending on the color and how dark it is. Pale pastels or beige may not have a noticeable difference.

 

The basement is below grade. The house was built in 1958, it has stone and mortar foundation walls and the previous owners finished the basement with drywall (basement is about 700 sq ft). The drywall is between 4" to 1.5' away from the foundation wall. There is no vapor barrier and the insulation touches the foundation walls in many locations (and thus very wet.)

By removing the old insulation and taking care of the water problem, I am sure I will resolve the humidity issues. I am also putting an industrial dehumidifier. The only question is whether or not there should be any new insulation put back.

 

It would be your call. If insulation has caused problems in the past, maybe it wouldn't be a good idea. Like I said, the temperature of the walls won't vary much, so the money you spend on insulation may not be beneficial beyond a warm and fuzzy feeling. You should apply a 6 mil vapor barrier between your studs and the final wall covering (sheetrock, wood, etc.).

 

Adding a vapor barrier would be a very costly task, as I will have to remove all the drywall... Right now, the contractor cut the bottom 24" around the perimeter to allow the installation of the new french drain.

 

What's holding your walls up?

 

The upper frame and the remaining drywall are holding the walls for now. Right now, the bottom part of the drywall as well as most of the studs are cut: