Is retrofitting exterior insulation on a foundation wall too risky?
Hope everyone is doing well. I have become a bit obsessed with exterior foundation insulation over the past few days. I really like the idea because of the added room on the interior and not having to build walls and use drywall. I have become a bit nervous about pest infiltration however and I’m deciding on it is even worth the risk. The complete area of basement is around 350 square foot. This is if I separate nothing and there are already 2 thick masonry walls on front and back of house that create partitions. The front wall is completely below ground and under a porch. East wall and back wall are 100% above ground. The back of house has a patio with a raised 1st floor deck above. My west wall is about 50-60% below grade. I’m in Westchester county, NY so not sure what products are approved and how much termite protection I need. My easiest solution would be to use adhesive to attach fp lite panels, they have an attached stucco surface, and put that around all above ground walls I can access and the top half of my wall below grade. The company that makes the panel also creates a metal z channel that can sit on top under wood siding. So I guess my questions would be:
1. With a mere 350 square foot in my climate zone how long would it take me to even out with the cost of insulation. If I didn’t insulate I would probably just insulate the rim joist which has nothing now and run 2 portable infrared heaters for periods when someone is down there. It won’t be a bedroom prob office, playroom, gym, nothing that would need to be heated overnight. Then run dehumidifier in hot summers.
2. Is everyone running away from exterior insulation because of potential termite problem? Is the risk not worth it. Is there professional companies that take care of the details in my area, what would I expect to pay?
3. One of the other reasons why I would prefer exterior insulation because I’m planing an addition on my west side wall in a few years. I figure any of my exterior insulation would just get buried in new addition. I would not have to worry about losing money on ripping out walls from interior. An architect told me if I built any wall on interior it would be ripped out with addition because of codes. Is this even true if I built a wall to code?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Hammer,
It is a bit unclear to me what you are really asking . (maybe because there are a lot of elements to it).
Retrofitting exterior foam is expensive and a major task. My yard is a frozen mud-pie (covered in snow) because of performing this operation late last fall (bad time of year to do so).
I would only undertake it if needing to also address existing water entry issues or when needing to insulate edge of a slab, both of which were issues for me (slab attached to structure with basement). I only snipped one siding board with the excavator bucket once the sun went down while backfilling, but the clay soil isn't pretty once disturbed even if the siding gets away unscathed.
Tyler,
I guess what I’m asking is if it is worth it to attach rigid foam to my exterior foundation wall using a product like the one I posted below on my above grade concrete walls or is the risk of developing a termite and ant problem too great. Would it take years to recover the cost of insulation when I’m heating a 350 sq basement intermittently with infrared heaters. Yes digging out the entire basement would be costly and in my opinion not worth it considering I don’t have any moisture issue and most of my foundation walls are above grade. I’m basically just insulating whatever is exposed to outside air leaving underground alone.
FP Ultra Lite 1 in. x 2 ft. x 4 ft. Stucco Grey Foundation Panel
https://www.homedepot.com/p/203928664