Is it necessary for open cell spray foam to be in contact with the sheetrock?
GBA Editor
| Posted in Energy Efficiency and Durability on
We are verifiers for Energy Star and have recently visited a home that installed open cell spray foam in the wall cavities. Usually, in this type of install we see them over-blowing the foam and cutting it off level with the interior face of the studs. In this case, the contractor was concerned about waste, and so was blowing the bays almost completely full, but not quite. They were achieving the R-value they needed but leaving a slight gap between the insulation and the sheetrock.
Do we/they need to be concerned about creating a convective loop in the air space behind the rock?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
No, you don't have to worry about convective loops because they would be on the conditioned space side of the insulation. That's why closed cell foam can be sprayed into wall cavities at only 2", leaving a 1.5" gap between it and the drywall.