The masonry column below was sprayed with 2″ of 2LBS spray foam, yet one can clearly see all the mortar joints telegraph through the spray foam. The point is, that spray foam is incredibly sensitive to changes in substrate and spray foam’s thermal performance is tied to how voids in the foam that can either reduce the R-value or contribute to air leakage.
Wires, pipes, cables, framing members all have an impact and ideally should be kept to a minimum and at the very least tied to the warm side of the substrate so the rising foam doesn’t pull it out or create weaknesses in the thermal envelope.
