Insulating Rim Joist Beyond Foundation?
Completely below grade basement in Zone 5.
Poured concrete foundation
Water barrier/proofing sprayed on foundation.
R-5 rigid foam applied to foundation (on top of water barrier)
Rim joist insulated with roughly r-7 rigid foam foil faced on both sides. Over the insulation (interior side) is a 1/2″ piece of OSB. The floor joists butt into this OSB. The joints of the OSB were caulked.
I am finishing my basement and have been planning to have 1″-2″ of spray foam applied to the rim joist for more r-value and most importantly air sealing. However doing so will increase the r-value of the rim joist to more than double that of the foundation. Should I be concerned about having a rim joist with a much higher r-value?
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