The Seattle Times Ask the Expert Some thoughts on repairing your cement-asbestos roof

The Seattle Times Ask the Expert Some thoughts on repairing your cement-asbestos roof

Q: I have a question about a 1940s-era ranch home with the original cement-asbestos roof. The majority of the roof is in excellent condition, needing only a moss removal. The ridge and hip pieces have separated in many areas, and leak stains can be seen from beneath (the attic) in several areas. It needs repair, obviously. Also, since the roof can’t be walked on, the chimney has never been swept; I am concerned with the chimney condition and flashing. What are my options for repair, or am I better off replacing it altogether? It is about 2,000 square feet, a full hip roof design, so what are the costs and problems with removal?

A: Asbestos roofs pose quite the conundrum. Why pay money to remove possibly the best roofing material ever known to man? This roof will outlast any two roofs you replace it with, except maybe slate or clay tile.

Confusion arises between an cement-asbestos roof like what you have and an asbestos-containing roof, which has been "declassified" by regulatory agencies. The tar in asbestos-containing roofing (which can look like typical composition roofing) encapsulates it, preventing the fibers from being released. Cement-asbestos roofing has no tar and will release fibers when disturbed.

Repair to your roof may be possible, but unlikely, due to the lack of roofers willing to tackle the job. Cement-asbestos roofing cannot be walked on, as it is extremely brittle and will shatter with the first footfall. Since they rarely are installed with tarpaper beneath, even the smallest crack will result in a leak. All work, including repair, cleaning, chimney maintenance or simply retrieving a Nerf football, requires a man-lift, a hook-ladder, scaffolding and a Chinook helicopter.

You as a home owner may remove up to 48 square feet of asbestos materials without obtaining a permit. A $25 permit fee (Puget Sound Clean Air Agency, or 206-343-8800) is required for areas larger than 48 square feet.

Again, you can do this work if desired. In all cases, the roofing should be disposed of as a hazardous material. Alternatively, an asbestos-abatement company can remove some, or all, of it for repair or replacement. The thing to be acutely aware of is that a roofing contractor or a general contractor cannot do any asbestos removal/repair work unless appropriately licensed.

Ed Plikaytis with American Environmental Construction says air sampling from past cement-asbestos removal jobs has resulted in extremely low fiber counts in the area. If the individual pieces are kept wet, not dropped to the ground and not broken during removal, little or no fibers are released. Plikaytis estimates removal costs from $2 to $3 per square foot, but possibly higher depending on site conditions.

Removal of the hip and ridge caps and replacement with a complementary material (copper, metal) is an option to consider in lieu of complete removal.

This may allow you to walk up the ridges, retaining the original roofing as needed. Ray Wetherholt, a roofing consultant in Kirkland, suggests plastic shingles for patching in the field where and when cracks develop. Wetherholt and I would caution against the use of problematic fiber-cement shingles that would be a closer match cosmetically.

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