Exterior vs. Interior Basement Insulation
Building in CT zone 5. I’ve been advised by our builder not to insulate the exterior foundation. He has done this in the past and there has been significant termite damage despite use of termite flashing and treatment. Another consideration is that I am very sensitive to mold and would like to observe the foundation for 2 yrs for cracks resulting in water intrusion so they can be accessed for repair. I’m aware of the possibility of dew point condensation (especially on the above grade foundation interior) as a result of not insulating. We will run a Sante Fe (Thermastor) 70pt dehumidifier but I’m not sure if this will fully control dew point condensation. The basement will be heated.
I’d greatly appreciate feedback regarding these possible solutions.
1. Insulate the exterior foundation but leave a 2-3 inch gap in the above grade insulation to check for termites. This would complicate the issue of above grade protection of the foam (not sure how this would be done) and the uninsulated section would still be vulnerable to condensation on the interior.
2. Insulate the interior foundation at the above grade section only where it is most vulnerable to condensation. This would allow for observation and intervention if cracks occur. Any water intrusion occurring under the foam could easily be identified as it would drip down the wall. (The space would be dehumidified.)
3. A hybrid solution in which the exterior foundation would be insulated below grade and the interior foundation above grade. I’ve never seen any discussion about this approach and I am always hesitant to be first out of the gate on anything due to unintended consequences. Removing exterior foundation insulation would be a nightmare.
4. Leave it uninsulated for 2 years and use heat and dehumidification to control any condensation that might occur. Insulate the interior with EPS w/fire barrier or Thermax would remain a possibility at a later date.
Thoughts? Thank you
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