Leaks in the roof are seldom easily detected from the outside. If the attic has no ceiling, holes in the roofing are often readily visible from the inside, which can be marked by pushing wires through the holes to the roof surface. If the attic has a ceiling, there may be stains on the plaster indicating leakage.
If the roof is of slate, tile, wood shingles, or composition shingles, see if any pieces are broken, missing, or loose. Examine wood or composition shingles to see if they are warped, partly decayed, or disintegrated.
Asphalt shingles and roll roofing may be blistered or pitted and they may have lost some of their mineral surfacing. These defects are more likely to occur on roofs with southern exposures or those with a low pitch such as over porches. The metal fastenings used to hold roofing materials, such as slate, tile, and cement-asbestos, may fail before the materials themselves do.
Sheet-metal roofs should be examined for holes, cracks, corrosion, rusting, open joints, and defective fastenings. If painted, they should be examined for blistering and peeling. Examine the flashing around the chimney and vent pipes and in the valleys of the roof carefully for rust or displacement.
Leaves, rubbish, and birds’ nests in gutters may stop up the downspouts. If there are strainers over the mouths of the downspouts, see that they are clear. Notice also the conditions of gutters and conductor pipes, and determine whether they need replacing or require a coat of paint. Where foliage from trees or shrubbery is in actual contact with the roofing, it should be trimmed back to permit the free evaporation of moisture.
Skylights should be examined for signs of leakage. The frames may need repainting, and the putty around the glass may need to be replaced. See that the flashing around the base of the frame is in good condition.
In looking over the chimney top, see that all bricks are in place and well pointed. If there is a cap, it should be securely cemented to the chimney. If there is no special chimney cap, mortar should be spread over the top of the brickwork and sloped down from the flue opening to the outside edge of the chimney.