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

Rigid w/ reflective or without in Basement

Jarret | Posted in Expert Exchange Q&A on

I am building a conditioned basement in Los Angeles. I’m installing rigid on the 12″ foundation walls to keep heated air off the cold concrete. I thought I would use foil faced rigid to accomplish that.  However, I’m thinking I’d like some permeability. If moisture does collect on the foundation wall, it should be able to dry to the inside, so in this case I should not use foil faced rigid, right?

Which is the better way to go, foil or no foil?

Fyi, I will also fur off the rigid with 2×6 framing and fill with R-21 batts. The house has a lot of glazing, so California (Title 24) requires it meets robust insulation standards

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.

Replies

  1. Malcolm_Taylor | | #1

    Jarret,

    From Martin's blog: https://www.greenbuildingadvisor.com/article/how-to-insulate-a-basement-wall

    "Does interior basement insulation need to be vapor-permeable? No. The idea that a damp concrete wall should be able to dry towards the interior — in other words, that any insulation on the interior of a basement wall should be vapor-permeable — is mistaken. In fact, you don’t want to encourage any moisture to enter your home. Your concrete wall can stay damp for a century; that dampness won’t hurt the concrete."

  2. Jarret | | #2

    Thank you Malcolm. I had remembered reading that somewhere, but could not recall where.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |