Exterior insulation for cathedral ceiling

Q We bought a 2 1/2-year-old house with an uninsulated cathedral ceiling. We are bothered by the summer- heat gain which overworks the air conditioner. At the same time, we prefer not to insulate the inside which is of beautiful knotty pine. Could the asphalt shingles be removed, new insulation board applied on the decking, and the same shingles reapplied? W. T. Petty New Smyrna Beach, Fla.

A The asphalt shingles could indeed be removed but their reapplication would be economically unfeasible and otherwise impractical.

Obtain a price from a specialty roofer for a spray-on white roofing which not only waterproofs the surface but insulates right over the old shingles. This may be your best answer.

Otherwise, cover the shingles with rigid insulation board that is two or more inches in thickness. Follow with an application of either roll or spray-on roofing instead of composition shingles.

Why? Because nailing the composition shingles through the insulation-board thickness is impractical. Talk to your roofer about this process. He should inspect the roof, determine what kind and thickness of insulating board to apply , and what type of new roofing to use.