Method of Inspection
There are several methods of inspecting a roof. Typically, it is walked on, checked from a window above, on a ladder at the eave, or from the ground with binoculars. If at all possible, the roof should be walked, unless it would damage the material, such as older slate, or would be deemed unsafe for the inspector. As a minimum, a ladder should be placed at the eaves, and the evaluation performed from that location. Windows from above provide an excellent opportunity to evaluate as much of the roof as possible from that location. The last resort is inspecting it from the ground with binoculars.
Inspectors carry extension ladders in some markets. Florida communities are mostly ranch or one-story homes. Most home inspectors in Florida carry folding ladders. Many northeastern markets, such as Philadelphia, have mostly two-story homes, so many home inspectors carry extension ladders.
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.
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.
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.
Cement asbestos shingles (obsolete)
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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.
Roof slope is determined by vertical rise over horizontal run, expressed in inches, the second number always being 12. For example, if a roof rises at a rate of 6 inches per foot (horizontal), it is a 6/12-slope roof.
Roofs with slopes of 7/12 or less can be walked on in most situations. Some people do not have any difficulty climbing almost any roof, while others have considerable difficulty. You should never walk or climb a roof that you do not feel safe climbing.
A roof that is flat, close to flat or has depressions, and allows water to collect or pond, may be a defect. This will depend on the extent of the ponding and the amount of water that collects. The National Roofng Contractors Association (NRCA) says that if ponding water evaporates within 48 hours of the time it stops raining, it can be considered acceptable.
For more information regarding roofing related items, follow the links below or to the left.
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