How do home inspectors check a roof?
Friday, October 19, 2018
The two main things we look for are: 1) evidence of roof leaks, and 2) age and condition of the roof material. Age and condition are tied together as one item because there’s always a correlation between the two. In the absence of any other information, we look at the condition to determine the approximate age of the roof. Some roofs age a little faster or slower than average but, like people, there are definite signs of middle-age and then the relentless progression to senior-citizen status.
Different planes of a roof age in different ways, and we take that into consideration too. The south-facing side of the roof gets the most sun, and therefore the most ultraviolet damage. Conversely, the north-facing side gets the least sun and is more likely to have moss growth or mildew discoloration. Also, the heavy tree cover in many Gainesville neighborhoods can cause staining that makes a roof look older than it’s actual age.
We try to walk the roof whenever possible, but if it is too steep to safely walk or it’s wet after a rain, then we view it from a ladder at the edge. The surface provides clues for where to look in the attic underneath for leaks: missing or deteriorated flashings, and damaged or severely deteriorated areas of roofing, are noted and warrant a careful look in the attic for water damage. If the home is a type that does not have an attic, like most mobile homes and 1950’s modern ranch designs, we look at ceiling with an infrared camera for evidence of leaks.
Each roof material shows different signs of age. For shingle roofs, we check tab adhesion (how easy the front edge of each shingle flap can be pulled up) and granule loss on the surface of the shingle. The granules protect the shingle from UV-deterioration and, as they come loose and roll down into the gutter, the roof begins to age faster, with the edges starting to curl up. The photo above shows an example of shingles curling at the front edges and corners. Also, shingles with loose tabs will perform adequately during a normal rainstorm, but a tropical storm, hurricane, or even a severe thunderstorm, will catch the loose tabs and rip them off the roof, with water damage as a result.
Metal roofs corrode with age, and the fasteners are the first to show rust damage. We also check for proper fastener spacing and correct lapping of the panels.
Broken and damaged tiles, along with any improper installation, are noted at tile roofs, which are the most difficult to age by condition.
Built-up and modified bitumen roofs are used for low-slope applications (under “2 in 12” pitch) and show signs of aging similar to shingles, along with “alligatoring” (a spreading crack pattern loosely similar the back of a gator) of the roofing tar.
It’s an old cliché, but a good roof is the #1 protective element of your home. And a bad roof, once it starts to leak, can wreak havoc with the interior: staining, mold, and rot follow quickly. So, naturally we take roof condition seriously, and so should you.
Also, see our blog post How can I tell if the house needs a new roof?
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To learn more about roofs and attics, see these other blog posts:
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McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes