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Roof photos: P 138-P 144, P 215-P 217
When you finish inspecting the interior, you can start on the exterior. We'll start with the roof, but as I've said before, feel free to adapt the inspection process to any way you feel comfortable with. There shouldn't be any tree branches overhanging the roof. Overhanging trees cause damage to the roof structure and shingles if branches fall. Shade created by the branches can cause mold and deteriorate the roof shingles. If you can, use a ladder to get a close look at the roof from the edge. While inside the house, you should view the roof close up from the interior windows if possible. Evaluating the roof framing from the attic area is a necessity. This will enable you to make better conclusions and evaluations when you get to the exterior. If you can't view the roof closely, you should use a pair of strong binoculars to help you.
Check for any bowing sections of the roof ridge beam, roof rafters or the roof sheathing which would suggest expensive repairs are needed. If there are any bowing sections then make sure you have take another look at these areas in the attic, if it's accessible. You should see plumbing vent stack pipes protruding through the roof by one foot. These are needed to keep the plumbing drainage lines at atmospheric pressure. Maintaining atmospheric pressure is required so the plumbing lines drain properly. If there are no plumbing vent stacks then you might hear gurgling noises from the interior sinks and drains.
Check the flashing for all roof projections and adjoining sections. Flashing refers to the material used around all joints to prevent water penetration into the house. Areas of the roof that need this type of water protection are: the base of chimneys and plumbing vent pipes, roof valleys, skylights, and the joint where dormers protrude through the roof. A roof valley refers to the area where two slopes of a roof meet to form a drainage channel. A dormer refers to a window or room that projects outward from the roof structure. Flashing should be made out of copper or aluminum. On higher priced homes you may find lead-lined copper flashing. Lead-lined copper has a longer lifespan and costs more.
If you find a lot of roofing tar "slopped" around the base of a chimney or over existing flashing, recommend it be repaired. Roofing tar is only a temporary fix for water leaks. It's like putting a Band-Aid over a cut that needs stitches. Some homeowners cut corners and have tar installed to avoid the higher cost of new flashing.
Remember that if it's raining, the roof will look newer than it actually is because of the water on it. There is one benefit to doing a home inspection on a rainy day. That is you'll have a better chance of finding any roof leaks or water problems in the lower level. If there's snow on the roof, just tell the client that you can only evaluate the visible portions.
If the house has a shingle roof it must have a high enough pitch to prevent water leaks under the shingles. A minimum pitch of 4 on 12 is recommended for shingle roofs. This means the roof pitch should rise by at least 4 inches for every 12 inches of roofing area. The slope of the roof that has a southerly or southwesterly exposure faces the sun more often. This can cause roof shingles to become brittle and show signs of aging faster. The slope of the roof that has a northerly or northeastern exposure is more likely to have mold and decay fungi on the shingles. This is caused by the lack of sunlight.
In northern climates you may find wires along the bottom edges of the roof. These wires are used to heat the show and ice so it melts off the roof without causing an ice dam. An ice dam refers to ice and snow that has frozen at the base of the roof above the gutters. Since the ice is trapped by the gutter, it gradually melts and the water goes underneath the roof shingles. This leads to water penetration problems in the house. Some homeowners don't like the idea of wires in their roof. If this is the case with your client, then flashing can be installed under the bottom few rows of shingles to help prevent water leaks from ice dams.