Exterior

How do you assess the condition of a roof?

Asphalt shingles

Look at the joints between the tabs. If the granules between the tabs are intact, the shingles are satisfactory and will not leak. If the granules are worn off and the matrix is exposed or cracked, the shingles are not acceptable and the roof is likely to leak.

Learn more about asphalt shingles.

Built-up roofing

There are a number of things to take into account with built-up roofs.

If there are up to 4 small- to medium-size delaminations (separations), and the surface or flood coat is sound, the roof is acceptable.

However, if there are more than 4 delaminations, or if they are large, the roof is vulnerable and may need repairs.

If the flood coat (final coat of asphalt) is worn, but the felt paper is not deteriorated, the flood coat can be re-applied, and the roof is acceptable.

If the flood coat is worn and the felt paper is cracked, separated, or shows deterioration of at least one ply, the roof may need repairs.

Learn more about built-up roofs.

Slate

The severity of the stains or delaminations is the best indication of the general condition of the slates.

Whitish stains on dry slates indicate that the slates are delaminated (separated) and are evidence of progressive deterioration. The thickness of the slate may help to determine the dependability of delaminating slates. Thinner slates (about 1/4'') may have a life expectancy of approximately 50 years if they are facing the south or west. Thicker slates (1/2'' or more) may have a life expectancy of 100 years or more.

Another consideration is that the fasteners securing the slates rust through in 60–70 years. This increases the amount of maintenance for slate roofing.

Learn more about slate roofing.

Cement asbestos shingles

The condition of cement asbestos shingles is usually dictated by age, and to a lesser degree, abuse. Cement asbestos shingles are generally 1/8'' thick, however, some 1/4'' shingles are still in use today. The 1/8'' shingles become fragile on the southern exposure when they are about 45–50 years old. The 1/4'' thick shingles will last 90–100 years. If you can break the corners off, then it means that the shingles have become too fragile and may need to be replaced.

Learn more about cement asbestos shingles.

If you are a client and your question is not answered above, Inspector