Please help with basement insulation

[Spork]

After finding out I had termites I also found mold in my basement! A section of my basement is above ground and insulated by the builder with fiberglass and the vapor barrier on the inside of the basement. I live in IL so its very hot and humid during the summer. So I'm now in the process of getting rid of the insulation and cleaning up the mold with vinegar.

I picked up a dehumidifier but can't decide on what to replace the insulation with. The spray in foam I think would be to expensive for calling someone out. Would going with the 2 inch rigid foam board be ok? I guess the stuff also has to be covered with drywall for fire code. Was hoping to leave it exposed for easier termite and mold inspection in the future. Then again I'm guessing the drywall could further help with insulation.

I've asked in a few places and not getting any responses. What are the alternatives to stuffing mold food in the walls?

thank you

[Tony Hwang]

Hi, Your first priority is controlling humidity. Air circulation(venting) is big part of it.

[Spork]

I bought a dehumidifier and plan to open the full size windows that we have in the basement more often. Would opening the windows possibly let more humid air in from outside making it worse?

[Tony Hwang]

Hi, Humid air is heavy. If your house has central a/c, it'll help lower humidity inside house and circulates air as well. Mold is bad news even can be health hazard. Usually bleach is used to clean and kill it. Until you are sure humidity problem is solved and mold is taken care of, better hold off on insulation.

[HeyBub]

1. Drywall IS for fire suppression, but I can't imagine how it would be any use in a basement. The dirt on the other side won't burn.
2. Drywall has virtually no insulating properties (R-value = 0.45).

[ransley]

Walls that get damp or leak cant be sealed shut, as you see you get mold. buy a moisture meter to determine where walls are damp, if you cant stop it or get it below 15% you cant use fiberglass and drywall, I gave up and just used foamboard screwed in so I can remove areas and check for mold. Spray down the walls with a garden sprayer with bleach to kill whats growing and keep the humididty at about 65% or less with the dehumidifier. If you rush to redo it without knowinging whats really happening it will mold all over again. Many old houses cant be drywalled and insulated with fiberglass as the walls never dry out in summers rains.

[ransley]

de quoted text -

20 sheets would insulate, its bullet proof too.

[Shaun Eli]

The dirt won't burn but if a fire starts in the basement the foam insulation would burn, hence the need for drywall.

[dss]

Spork,

The first step is to determine where the moisture is coming from. It could be from the outside and you need to do something with drainage (landscaping, gutters, etc.) or wall repair. It could be an interior problem with cold water pipes sweating and general humidity. Insulate the cold water supply pipes with foam sleeves. It's most likely a combination of the two.

Check with your local building code authority to see what they recommend. Some cities have that information on-line. In my part of Minnesota they now require two vapor barriers; one between the exterior wall and the interior insulation (just up past the ground line) and another one between the insulation and the full finished interior wall. Space is left at the top to avoid the moisture sandwich. This is a recent change from just an interior vapor barrier (the Canadians have been doing it with two for years).

Watered down bleach will do a fine job killing the mold and it won't come back if you solve the original problem. Foam boards properly sealed with caulk and the small cans of foam should do the trick, but then you do need drywall as the foam burns easily. Don't leave the windows open if you're running the dehumidifier. If you can air condition the space properly, you don't need the dehumidifier.

Good luck.

dss

[HeyBub]

Good point, but it depends on the foam. For example, polystyrene (packing peanuts) doesn't burn. It will char and melt, but won't support combustion.

I would suspect the type of foam used for insulation is of the non-flammable variety.

[ransley]

Alot of construction foams wont burn, they smolder and the poisonous smoke will kill you before you know of the fire.

[clare]

But it WILL produce poisonous gas if held to a flame. Styrene in particular MUST be covered with a flame barrier by law, and for good reason.

And your suspicion would be wrong, and dangerous.

[hrhofmann]

Cyanide gas is produced, I would try to avoid generating it.

[Spork]

thanks everyone for the help. My basement is partially above ground so it has studs and osb as part of it after about 3 feet of foundation. This is where I found the mold growing after peeling back the insulation. I've taken care of the dampness with the dehumidifier and cleaning up the mold. I was looking for something more mold resistant than fiberglass to replace it with. I already know foam is the best option for directly against the foundation. Looks like I will be using it for the studded areas also. Will have to cover with drywall then to make it safe.

This stuff looks promising as well. Works similar to the foam and fire resistant/bug resistant.

[hallerb]

paint walls with drylock paint, add extra mold killer paint additive for extra precaution.

[DanG]

If you were starting from scratch:

Mastic or other water/damp proofing membrane on concrete Rigid foam installed on concrete. Taped joints.

1" dead air Stud wall with gyp. NO vapor barrier.