Methods of insulating masonry-wall houses

Q Our house has heat loss in winter and heat gain in summer because the exterior walls are incapable of insulation. How can I insulate these outside walls?

Louise Artiges Clearwater, Fla.

A Apparently the exterior walls are solid masonry. Right? Thus you can't have any insulation material blown into the wall cavities because there aren't any cavities.

On 16-inch or 24-inch centers, apply 2-inch-wide vertical wood furring strips on the inside faces of the exterior walls. The thickness of the strips should be the same as the thermal insulation board which you choose for insulation.

Apply the insulation material between the strips. Cover the end result with a drywall material, such as gypsum wallboard or wood paneling. I'd not use wet plaster in an existing house.

Various types of thermal insulating boards can be found at your local supply house. Check them out. Compare ''R'' factors to board thickness. Choose the maximum R-value material having a 11/2-inch thickness.

An alternate method is the application of furring strips with insulation between, covered with a weatherable finish on the outside of the exterior walls. This method is more costly, but you may have good reason to take this alternate route ahead of the first suggestion. You make the decision as to which method is right for you.

Either method requires the appropriate recasing at all window and door openings in order to handle the additional wall thickness there.