Vinyl siding over asbestos shingles

Vinyl siding, indeed, can go over asbestos

Many houses built in the 40 s

As it ages, the factory finish deteriorates, but even then the shingles can be painted. So, when new siding is installed on houses having asbestos-cement siding, it's usually done to improve or update the appearance of the house and not because the shingles are worn out.

Although asbestos-cement shingles contain asbestos, a carcinogen, they are considered nonfriable and are not regulated as a hazardous material as long as they are not crumbled or reduced to powder.

Siding shingles are nonfriable because the asbestos fibers are held in place by a cement binder in the shingles.

But damaging the shingles can release some of the fibers. So, whether the shingles are to be sided over or removed, the methods used should avoid breaking, cutting or abrading the shingles. Some experts recommend screwing, rather than nailing, when new siding is installed over existing asbestos-cement siding.

If the shingles are to be removed, they should be wetted during the process to prevent fibers from becoming airborne, and they must be properly disposed of at a landfill.

There appears to be no overriding advantage to either removing the shingles or leaving them in place. There may be a benefit to having a layer of tough, fireproof asbestos-cement shingles under the new lightweight siding.

One area where leaving the old shingles in place could be impractical is where exterior trim projects just barely beyond the face of the existing shingles.

Inspector's Eye

Dean Uhler has been a home inspector for more than 12 years and is president of Baltimore-based Boswell Building Surveys Inc. Uhler is a member of the American Society of Home Inspectors (ASHI) and is the treasurer of the Greater Baltimore Chapter of ASHI.

Questions, with name, address and daytime telephone number, about homes and home inspections can be faxed to 410-783-2517, e-mailed to or mailed to Inspector's Eye, Second Floor, 501 N. Calvert St., Baltimore, Md. .


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I had vinyl installed over asbestos shingles

Installed 3/4" rigid foam insulation over the tiles then siding over that. the windows were cased in aluminum and have a tapered transition to meet the depth of the old windows. loots good. the only thing is that the casing is about 6" wide around all the windows, vs. the smaller casing. it actually came out pretty good. you can email me for some pics if you want

In my opinion one product applied over another

Usually fails or looks like crap or eventually is a pain in the ass for someone else in the future.
Some examples are:
1.Asphalt shingles over asphalt shingles, Increases the weight on the roof, increases the amount of heat stored, new shingles subject to fail prematurely if shingles below begin to curl. A carpentry book showed a picture of a roof where someone put on two or three layers of shingles, when the 3rd layer needed replacing they nailed plywood sheathing on top to get a fresh base and applied the 4th layer. Imagine being the next owner.
2. Aluminum siding over wood siding

Ogdensburg home rehabilitation program gears up for phase two, on schedule  —
Some homes will receive extensive and visible rehabilitation, including the installation of vinyl siding, roofing and windows. Other homes won't have an obvious exterior update but will have new furnaces or flooring put in.

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