by Kenton Shepard and Nick Gromicko
The purpose of the series “Mastering Roof Inspections” is to teach home inspectors, as well as insurance and roofing professionals, how to recognize proper and improper conditions while inspecting steep-slope, residential roofs. This series covers roof framing, roofing materials, the attic, and the conditions that affect the roofing materials and components, including wind and hail.
Repairs are evidence of past problems. It’s common for underlayment to be torn during repairs but uncommon for that underlayment to be repaired, so look for signs of leakage below any repairs you find.
It’s possible that the roof leaked before the repair was made, so stained materials should be tested with a moisture meter for elevated moisture levels.
If there’s been no recent rain or snow in the area, the stain may be dry even if the roof still leaks, so if you find normal moisture levels when you test, you should mention in your inspection report that you tested but the results may be inconclusive because the weather was dry during the days or weeks before the test.
Leaking Slate Roofs
Regarding moisture and roofs, there are two general rules to keep in mind:
Just as with other roof-covering materials, there is often more than one way to install slate roofs correctly. When you inspect the installation, check to see if the slates and flashing were installed using a method that keeps moisture from penetrating the roof, and in a way that will not cause premature failure.
These are all areas you should look at closely during an inspection:
If the roof appears to be in good condition, leaks may also be from the masonry. If through-wall flashing has not been installed, heavy rains may cause moisture to migrate through masonry.
It’s not unusual for insects or bats to live in a slate roof, especially roofs with heavy slate. Insects may sting and bats can transmit rabies, so be careful. Since you will probably not walk the roof, these pests my be difficult to spot. You may see insects during their normal daily activities, but bats are seldom seen unless they’re disturbed.
Slates hung on steep roofs may rattle in the wind, and the noise they make is referred to as chattering.
Learn how to master a roof inspection from beginning to end by reading the entire InterNACHI series: Mastering Roof Inspections.
Take InterNACHI’s free, online Roofing Inspection Course
Mastering Roof Inspections
Roofing Underlayment Types
Inspecting Underlayment on Roofs
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