18 months to 2 years; in other locations, after 2 1/2 to 3 years.

ALUMINUM ROOFING. - Aluminum roofing, properly applied, does not normally require maintenance. Failures in aluminum roofing that result from improper application are essentially the same as those encountered with galvanized-steel roofing and are repaired similarly.

Flashing

Failures to roofs are usually attributed to the roofing material; however, frequently caused failures are actually due to improper installation of the flashing material. These areas should be the first to be inspected when leaks in a structure are reported. A good procedure to follow is to make a careful inspection of the roofing material near the flashings for signs of moisture. Punctures, broken laps or seams, separation of flashing from vertical surfaces, and deterioration from weather are causes of failure.

If a separation occurs between the base flashing and a wall, refasten the base flashing to the vertical surface by nailing or cementing. Recoat it with a plastic flashing cement and replace with the correct counter- flashing.

Leaks sometime occur around vent flashing. The majority of vents are constructed of metal and, consequently, are subject to expansion and contraction. For this reason, it is poor practice to attempt to flash up the sides of such projections because this type of flashing is subject to early failure. Vents are usually of two types: the flat flange vent and the curb flange vent. The flat flange vent is placed directly upon the last ply of roofing, whereas the curb vent is constructed to fit over a wooden or concrete curb. When exposed nails that hold a flashing flange to a roof work loose, as shown in figure 7-11, raise the flashing flange high enough to force plastic cement beneath it and replace the loose nails. Apply two plies of felt or fabric cemented to each other and to the flange with asphalt, pitch, or plastic cement. The outer edge of the first ply of felt or fabric should extend not less than 3 inches beyond the flange and that of the second ply of felt or fabric not less than 6 inches. Apply the finished surfacing similar to existing roof surfacing.

Drainage Systems

It is important that drainage areas be kept free from debris that will interfere with proper drainage. Many

Figure 7-11. - Separation of metal flashing flanged from roof-caused by exposed nails that have worked loose.

roof failures can be traced to inadequately maintained drainage systems. If during a semiannual roof inspection you notice the accumulation of debris in gutters and around drains, take action to make sure that all debris is removed to prevent subsequent roof failure.

PAINTED SURFACES

Paints are not indestructible. Even properly selected protective coatings properly applied on well- prepared surfaces will gradually deteriorate and eventually fail. The rate of deterioration under such conditions, however, is slower than when improper painting operations are carried out. Inspectors and personnel responsible for maintenance painting must be familiar with the signs of various stages of deterioration to establish an effective and efficient system of inspection and programmed painting. Repainting at the proper times prevents the problems resulting from painting either too soon or too late. Painting scheduled before it is necessary is uneconomical and eventually results in a heavy film buildup leading to abnormal deterioration of the paint system. Painting scheduled too late results in costly surface preparation and may cause damage to the structure, which then may require expensive repairs.

Inspection of Painted Surfaces

All painted surfaces should be inspected at definite intervals. They should be inspected semiannually in exterior and corrosive environments, in areas where heavy traffic may cause rapid wear (floor finishes), and in areas where sanitation is important. Other areas should be inspected annually. The inspector should observe their condition for the type and stage of deterioration and make