Bad idea?

[BobT]

I've been considering adding some Styrofoam insulation to my basement walls. I figured I wouldn't do the entire wall but just the top four feet (width of sheets).

Someone suggested that I could possibly introduce a potential for frost to push my walls in by doing this. I have my reservations though.

Would this be beneficial or is it true that it might be risky?

Thanks,

Bob

[Roofer]

Why not just do the whole thing and be up to code requirements? Use 1 1/2" Thermax.

[BobT]

My basement walls aren't moisture proof. In the spring following snowy winters I will experience some water penetration during the thawing process, especially in part of my basement. I added new basement to about half my house (didn't have any when I bought it) and in that new section we installed a tile. We didn't install tile around the entire house however and in the old section I can have some water penetration as I described. I'm concerned that lining the bottom portion would potentially cause mold problems because I'd trap the moisture between the walls and the foam.

I didn't know there was a code requiring unfinished basements to be insulated.

Bob

[Roofer]

The code is only for new construction or additions. Nevertheless, it creates your energy wall and saves on heat.

Sounds like you may want to get some Drylok or similar and some drain tile.

Sorry I can't answer your initial question.

[sparcebag]

I believe The current code states all joints and edges of rigid insulation installed on interior block walls shall be taped,I also believe the tape is the pink tape used on exterior moisture barrior(tyvek)

The rigid is glued on then taped,If installed properly there is no air available to promote mold,mildew growth.

[Surface Tension]

If your doing the outside just above grade, the ground around the house will still be thawed so no there shouldn't be any heaving. That is what I would do. Whats happening come Spring is the snow melt can't sink into the frozen ground, well except for the thawed ground around the house. I would add fill around the house and or make a swale where the water can be diverted away from the house.

Insulation on the inside top 4' of the wall won't do anything.

[Surface Tension]

You we're replying while I was typing. I'd be afraid of insulating in interior wall if there was any history of leakage.

IMO, any wall will leak if the water is allowed to get there.

In addition to my above post gutters and downspouts that divert that water away.

I'll add that I have the swale and proper grading in one location. In the Spring I still have standing water 6' from the house. Solution was to sink a 5 gallon bucket at the low spot tap into that with 2" PVC and daylight it. I then put heat tape in the PVC and only need to plug it in once to thaw it out.

[Roofer]

I don't believe just any rigid foam is up to code just by taping it. Thermax does give you the vapor barrier with the correct tape. Other rigid foam still needs poly.

[sparcebag]

Ya I guess I missed that.I was speaking foil backed.