We have a family room with a cathedral ceiling which gets very hot in the summer. This is in the bay area in CA.

The cathedral ceiling has 2×6 rafters with plywood sheathing/asphalt roof on top, drywall on bottom.

I removed the eave blocking and pulled out the fiberglass batts which were original insulation. Maybe R-11?

The cavities are 8 feet tall and accessible from the both the attic (top of cavity) and the outside (removed eave blocking).

I thought I could just have closed cell polyurethane foam sprayed into cavity from top and bottom, being careful not to overfill and pop the drywall on the ceiling side. This would give our cathedral ceiling a much higher R-value (R-26?) and hopefully keep it cooler. I imagined you could use a long wand to spray foam and slowly retract wand as cavity fills with foam. Since cavity is accessible from top and bottom, you could do 4 feet from the top and 4 feet from the bottom using a gun with a 40″ wand.

But Tri-County Insulation estimator said they will not spray polyurethane foam (open or closed cell) into a closed cavity as it will not cure due to lack of air/moisture. He said the uncured foam will remain wet.

I’ve been scanning this forum and haven’t seen anything about curing being a problem.

The problems I’ve seen for foam in closed cavities seem to be related to the foam setting up before it has a chance to settle into cavity, leaving voids. Or that foam cannot make it’s way past obstacles in the cavity. But this was for wall cavities, where as I have a nice open cathedral ceiling with cavities which are 22″ wide and 5.5″ tall with no obstructions.

Is the estimator correct about curing for closed cell polyurethane foam?

If not, can anyone recommend a insulation contractor which can handle this job?