Pitched roofs 6
Asphalt shingles 9
Wood shingles and shakes 11
Asbestos-cement shingles 12
Slate shingles 13
Clay tiles 14
Flat roofs 14
Builtup roofs (BURs) 16
Single-ply membrane 17
Roll roofing 17
Metal roofing 17
Checkpoint summary 18
Every roof has two basic elements—the deck and the weather-resistant covering. The deck (also called roof sheathing) serves as a base for supporting the roof covering that protects the structure from the weather. A proper roof inspection includes an evaluation of both the roof covering and the deck. Even though a covering might be in good condition, the deck underneath might be soft, spongy, and structurally unsound. This condition can be caused by rot or delamination and is not necessarily noticeable in an exterior inspection.
The technique used for inspecting the roof differs depending on whether the roof is pitched or flat. Pitched roofs are checked during your initial pass around the house. Because of the hazards involved, I do not recommend that you climb onto a pitched roof. Begin your inspection by stepping far enough away from the house so that you are able to see all exposed sections of the roof as you circle the structure. The use of binoculars is recommended for this inspection to get a close-up view of the roof.
As you walk around the structure looking at the roof, make note of any uneven, sagging, or damaged sections. Unevenness in the roof might be the result of warped sections of deck or a poor installation of a second layer of shingles. This condition is usually not a problem. However, shingles in uneven areas are more vulnerable to damage and water intrusion. Make a note on your worksheet of the approximate locations of the uneven areas. During the attic inspection, you should check these areas for signs of leakage and to verify the cause of the unevenness.
Sagging sections in the roof, on the other hand, might be symptomatic of a structural problem or might reflect a problem that has been corrected. A sagging ridge beam or roof deck could indicate a structural failure, inadequate bracing, or inadequate spacing of wood-frame support members. The condition causing the sagging might have stabilized, so that no further corrective action is necessary. If you see a sagging ridge beam or sagging section of deck during your first pass around the house, have this condition evaluated by a professional.
Damaged sections can occur from falling tree limbs or swaying tree branches that overhang the roof. If you see a damaged section, record its location on your worksheet, since it must be repaired. Usually, patching the damaged area is all that is required.
Ventilation of the area directly below the roof deck is very important, especially in newer buildings where the deck is constructed of plywood panels rather than tongue-andgroove boards. If the area is inadequately ventilated, a moisture buildup can eventually cause the plywood sheathing to delaminate. This moisture problem is particularly acute in homes that have cathedral ceilings constructed in the following manner: The ceiling is plasterboard or an equivalent type of panel nailed directly to the roof rafters. Above the ceiling is insulation, and above this is the roof deck. Often there is a small air space between the insulation and the deck. When the moisture normally generated in the house by cooking, bathing, and so on reaches the area of the deck, there must be vent openings through which it can escape. Otherwise, rot and delamination can occur. A high percentage of the homes built with this type of cathedral ceiling have inadequately ventilated roof structures. Vent openings are needed near the top of each channel formed by the roof rafters and the ceiling and are also needed around the soffit. Often, only the soffit vents are installed. Vent openings for the top portion of the rafter channel can be provided through individual roof vents or a ridge vent. (See FIG. 2-1.) When the cathedral ceiling is the exposed roof-deck planks or panels, there is usually a rigid insulation on the top side between the deck and covering. This type of construction will not result in a deck having a problem with moisture accumulation, and therefore venting is not necessary.
If your house has a cathedral ceiling with no vent openings near the ridge, anticipate problems with the roof deck. You can tell if you have a deck problem by walking on the roof. If sections of the deck yield with each step and feel soft and spongy beneath your feet, there are problems. Note that you should not attempt to walk on the roof if the pitch is steep or the shingles are a type that can easily be damaged, such as tile or slate. Also, if the roof is not readily accessible from a deck or an intermediate level area, it is best to leave this part of the inspection to a professional. Even if the roof deck shows no signs of a problem, if the area is not adequately ventilated near the top of the roof, the installation of a ridge vent should be considered to prevent future problems.