GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Spray foam basement ceiling to block moisture and improve efficiency?

bencarsan | Posted in Energy Efficiency and Durability on

Upstate NY–The homeowner bought a home not realizing that it was in a flood plain. Over the last 5 years the basement and crawl space have flooded up to the rim twice, taking out the boiler and water heater, which have been moved upstairs. When it’s not flooded, the basement + crawl have high moisture levels which is causing mold upstairs as well. We’ve been asked to fix moisture and improve efficiency. Ideally, we’d raise the building three feet, but the money isn’t there.

Here’s the question: can we spray foam the basement rim and ceiling and install an HRV upstairs? I am nervous about rot and mold below. Also about whether the minimal heat loss from above will be enough to prevent frost damage to foundation walls?

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. GBA Editor
    Martin Holladay | | #1

    If the last 5 years are any guide, it sounds like this house floods "up to the rim" every 2.5 years. You are asking whether it makes sense to install spray foam on the basement rim and ceiling, and install an HRV upstairs.

    My opinion: the work you suggest will cost thousands of dollars, and it is money wasted. It makes far more sense to take the $5,000 you plan to spend on spray foam and an HRV and to invest that money in a better plan: jacking up the building and adding 3 or 4 feet to the height of the foundation.

  2. bencarsan | | #2

    Thanks Martin. I share your view--this goes against our instincts too. The house needs to be raised up, and this feels like kicking a big problem down the road. However we are working with a low-income rehab program that funds basic necessary repairs for those who qualify and probably won't fund structural improvements on the scale of house jacking ($10-$15,000 last time I checked). It's a tough situation, and I am looking for a workable improvement that leaves the homeowner better off than they are now. Can you elaborate a bit on "money wasted"? What might we be risking with this approach?

  3. GBA Editor
    Martin Holladay | | #3

    Here's how the money might be wasted: If flood waters rise again, raising the moisture content of (or soaking) the mudsill, rim joist, or floor joists, then the spray foam will impede drying. At that point it may be necessary to try to peel away all of the spray foam to allow the wooden components to dry out.

  4. wjrobinson | | #4


Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |