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What should my builder do?

One of my builders is asking if he really needs to put batt insulation in the basement bedroom walls if there's already R15 continuous on the exterior. Is it overkill? Our code requires either R10 cont or R13 batt. He could also use more continuous on the interior (because it's donated). Any thoughts on doing this? Thanks for your input!


  • Nope not per code & not really a big fan of anything but closed cell being placed against a wall where moisture could be an issue / still needs to dry out. As for more continuous, any worries about moisture - how are you handling water / moisture?
  • David ButlerDavid Butler Posts: 3,889
    I have specified batts on interior basement walls with no exterior insulation, but always with a layer of XPS between furred out stud wall and basement wall, R value depending on climate, and how much of the basement wall is above grade. With R-15 outboard, it would be overkill to put batts + another sheet of foam board on the inside. Also, as Sean mentioned,, you wanna be sure the basement wall will be dry before adding any foam on the inside. Even if exterior is handled well, good drainage away from foundation, the basement wall itself, if pour-in-place, will take some time to dry, and it needs to dry to the interior.
  • Thanks, David & Sean! Yes, we were concerned about moisture.