Roof Air Conditioner Creates Problem That’s Hard to Shake

Question: Several years ago we had an air conditioner/heating unit placed on the roof directly over our L-shaped kitchen and breakfast room area. We can’t move it because we’re on a hillside pad and there is no outdoor area where it could be placed. Month by month, the vibration from the unit on the roof began to cause tiny cracks in our plastered ceiling. We’ve had them repaired properly, but they come back and become deeper. Now they are beyond hope. I don’t want a false ceiling; my kitchen decor is country (one wall is brick) and it wouldn’t suit at all. My own answer would be a wood ceiling for appearance, but I need all the natural light and reflection I can get. Any ideas?

Answer: I would put furring strips, say 1x2 boards, on the plaster and then install a new drywall ceiling to the furring strips. The furring strips will help secure the plaster that is cracking and provide a stable backing for the the new drywall.

To carry out your country decor and keep the kitchen light, I would consider wallpapering the drywall ceiling with a light background paper in a small Early American pattern--not the walls, just the ceiling.

Even more important, however, is getting to the source of your problem; that is, the vibration that is causing the cracks in the ceiling. Check with an air conditioning/heating firm to see if the unit can be mounted on a sponge- or rubber-type base that would absorb the vibration. There’s no guarantee that whatever you do to the ceiling will not suffer damage as long as the vibrations continue.

Q: In the various ads for fireproof roofing, they always state “reroof over existing roof.” Is there an advantage to this other than labor saving?


A: We talked with one of our roofing sources, Carrol Heetland of Heetland Roofing Co., 14200 Besemer St., Van Nuys, about your question.

He says unquestionably the labor savings (cost savings) is the primary advantage. But also important are the debris and dust problems involved in removing a roof. He says, for instance, that shake roofs, which usually must be removed, split and sometimes fall down into the attic area, where among other things, they could be a fire hazard.

And with the removal of any kind of roof, there is a dust factor. I would say, put the new roof over the existing one whenever it’s feasible.

Dale Baldwin will answer remodeling questions of general interest on this page. Send your questions to Home Improvement, Real Estate Department, Los Angeles Times, Times Mirror Square, Los Angeles 90053. Baldwin cannot answer questions individually. Snapshots of successful do-it-yourself projects may be submitted but cannot be returned.