The rock granules that coat the surface of asphalt shingles are important. They protect your roof surface from deterioration by the sun’s UV-light rays. When you see piles of the coarse sand-like granules in your gutter, like in the photo above, or a faint ribbon of granules on the ground under the drip edge, it means the roof is gradually losing its UV-protection.
Granule Loss Indicates Aging Of A Roof
Because granule loss is one of the signs that a roof is getting older, it is used by inspectors as a gauge of roof condition and a way to estimate additional roof life. Some other aging clues are curling at shingle corners, lack of tab adhesion, and broken-off pieces as the shingles get more brittle with age.
You can also tell if you’re experiencing granule loss by looking up at your roof for a mottled granule texture on the surface of the shingles, which will progress over time to become areas of clearly discernible bald spots. And, just like male-pattern baldness, it tends to follow a predictable pattern, starting at the leading edge of the shingles and working its upward, as in the photo below.
Places like the ridge line that have more weather exposure, and valleys that get more rainwater flow over them, both tend to be the early spots of granule loss that’s clearly visible.
More advanced granule loss looks like this close-up.
Once the shingles lose their protective layer, they gradually become brittle and easily damaged. This is the point where roof leaks begin.
For more on evaluating the condition of an aging roof, 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:
• Why is my roof sheathing sagging between the trusses?
• Why is granule loss a problem for an asphalt shingle roof?
• What are the mistakes to avoid when doing attic improvements?
• What causes roof shingles to curl up at corners?
• What causes shingles to buckle along a line on the roof?
• What causes leaks at a fake roof dormer?
• What causes a sagging roof ridge line?
• What causes bubble-like blisters in a built-up and gravel roof?
• Why does it cost so much more to replace a steep roof than a low slope roof?
• What is "ponding" on a flat roof?
• Is an attic required to have a light by the building code?
• How can I inspect my roof for hurricane damage?
• Why is premature curl of roof shingles a problem?
• How can I tell if a roof has more than one layer of shingles?
• What are the common problems with attic insulation?
• What is the life expectancy of an asbestos cement shingle roof?
• What's the average lifespan of a roof?
• Why is it a mistake to replace a roof and not replace its flashings?
• Why is there no attic access hatch in the house?
• What is the building code requirement for an attic access hatch, scuttle, or door?
• Does a roof with multiple layers of shingles last longer?
• What can I do to prevent roof leaks?
• Are roof trusses better than roof rafters (stick framing)?
• Why is a popped nail in a shingle roof a problem? How do I fix it?
• What are the most common problems with wood roof trusses?
• What causes a lump or dip in the roof?
• If my roof is not leaking, why does it need to be replaced?
• How can I be sure my roofing contractor got a permit?
• How many layers of roofing are allowed on a home?
• What are the dark lines running parallel to shingles on my roof?
• Can metal roofing be used on a low slope/pitch roof?
• How can I make my roof last longer?
• What are the warning signs of a dangerous attic pull-down ladder?
• How can I find out the age of a roof?
• Should I buy a house that needs a new roof?
• Should I buy a house with an old roof?
• What are those metal boxes on the roof?
• What does "lack of tab adhesion" in an asphalt shingle roof mean?
• Why do roof edges start leaking?
• Why do my dormer windows leak?
• Do home inspectors go on the roof? Do they get in the attic?
• Should I put gutters on the house?
• How much of a roof truss can I cut out to make a storage platform in the attic?
• What's the difference between an "architectural" and a regular shingle roof?
• What does a home inspector look for when examining a roof?
• Do stains on the ceiling mean the roof is leaking?
• How can I tell if the house needs a new roof?
• Why does my homeowner's insurance want a roof inspection?
• What are the hazards to avoid when going into an attic?
Visit our ROOF AND ATTIC page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.