If I use foam insulation in the exterior walls do I need a vapor barrier?



Should I still us a poly sheeting over the inside wall?
(Using foam sheets, not expanding/sprayed foam)
insulation with a poly sheeting or kraft faced fiberglass? Which would you recommend?

Further Reading

Published by Walter Franks on Aug 21, 2009 under DIY

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2 Responses to “If I use foam insulation in the exterior walls do I need a vapor barrier?”

  1. Comment by Michelle S

    Yes you should because of possible condensation. Wherever warmth from inside meets cold air from the outside you should use the vapor barrier. Especially in your basement.

  2. Comment by Matthew W.

    I want to add insulation to existing exterior walls. Adding a moisture barrier is not an option because it will be injected or blown in depending on type. Will lack of a moisture barrier be more of a problem with one type of insulation as opposed to another? My preference is to use an organic foam. I live in temperate San Francisco.

    Thank you