Okay to use Open Cell foam over existing batt insulation or foam board? I'm located in Zone 5a.
I have a bonus room that has accessible 3 walls and the ceiling. The room is already insulated on the walls with R-11 and R-3 foam board. I have had two contractors now tell me that they can spray over the existing insulation with open cell foam vs. removing it. I'm curious as to why it wouldn't be better just to remove all the existing insulation [wall and ceiling], spray foam the back of the drywall between the studs; and then put back up the R-3 foam board on the walls and batt insulation up on the ceiling? I would think it is technically a better air seal by applying directly to the drywall and any cavities present vs. spraying on top of existing insulation?
Posted Jan 16, 2012 9:09 PM ET
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