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ROOFING INSPECTION & REPAIR
AMERICAN CEMWOOD ROOFING
BEST ROOFING PRACTICES
BUILT UP ROOFS
CATHEDRAL CEILING VENTILATION
CERTIFICATIONS for ROOFING CONTRACTORS
CHIMNEY FLASHING Mistakes & Leaks
COLD WEATHER ROOF TROUBLE
DECKS, ROOFTOP CONSTRUCTION
EPDM, RUBBER, PVC ROOFING
EXTRACTIVE BLEEDING on SHINGLES
FIRE RETARDANT PLYWOOD
FLASHING on BUILDINGS
FLAT ROOF MOISTURE & CONDENSATION
GREEENHOUSE / SOLARIUM ROOF LEAKS
HEAT TAPES & CABLES for ROOF ICE DAMS
ROOF ICE DAM LEAKS
MASONITE WOODRUF FIBERBOARD ROOFING
NOISE CONTROL for ROOFS
PLASTIC ROOFING TYPES
PVC, EPDM, RUBBER ROOFING
ROOF ARCHITECTURAL STYLES - PHOTO GUIDE
ROOF CLEANING RECOMMENDATIONS
ROOF COLOR RECOMMENDATIONS
ROOF DORMER TYPES - PHOTO GUIDE
ROOF INSPECTION SAFETY & LIMITS
ROOF JOB PROBLEMS, RESOLVING
ROOF LEAK DIAGNOSIS & REPAIR
ROOF NOISE TRANSMISSION
ROOF REPLACEMENT SNAFUs
ROOFING FELT UNDERLAYMENT REQUIREMENTS
ROOFING MATERIALS, Age, Types
ROOFING TILE SHAPES & PROFILES
ROOFING UNDERLAYMENT BEST PRACTICES
SADDLE CONSTRUCTION at CHIMNEYS
SNOW GUARDS & SNOW BRAKES
STANDARDS for ROOFING
STRESS SKIN INSULATED PANELS
TEST LABS - ROOF SHINGLE
TREES & SHRUBS, TRIM OFF BUILDING
TRUSSES, FLOOR & ROOF
UNDERLAYMENT REQUIREMENTS on ROOFS
VENTILATION in BUILDINGS
WALK-ON ROOF SURFACES
WARRANTIES for ROOF SHINGLES
WORKMANSHIP & ROOF DAMAGE
ZINC METAL ROOFING
This roof leak article explains the causes & effects of loss of protective mineral granules from roof shingles. Shingle granule loss defects occur on organic-mat or fiberglass-mat asphalt roof shingles and, depending on the cause and extent of mineral granule loss, the loosening of this protective coating can spell the end of life of an asphalt shingle roof or the demise of a mineral-granule-coated roll roofing roof.
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Roof shingle granule loss may be normal shingle wear, hail damage wear, or defective roofing product, as we explain here. The page-top photograph shows severe loss of mineral granules from an asphalt shingle roof. This "bald" asphalt shingle roof is way past needing replacement and is almost certainly leaking. Even a roof with less dramatic granule loss is showing signs of wear and reduced future life. Readers are also invited contribute roof failure information to the web author for research purposes. web author for research purposes.
The job of these mineral granules which are adhered to the roof shingle surface as part of the shingle manufacturing process, is to protect the shingle from sunlight, from UV light, and from the weather in general.
The selection of roof shingle color is also determined by the choice of its coating of mineral granule; lighter colored shingles may remain a bit cooler and at least in some applications (hot sunny climates) may have a longer life than dark-colored shingles.
Types of Mineral Granule Loss on Asphalt Roofing Shingles
While in our page top photo the roof is "worn out", there are quite a few other conditions that can produce mineral loss on asphalt shingle roofs. Diagnosing the correct cause of granule loss is useful in helping to assess the probable remaining roof life and it may play a role in roof shingle warranty claims or insurance claims related to storm or hail damage.
Below we define, contrast, and illustrate all types of mineral granule losses that occur on asphalt roofing:
Granule loss due to normal wear and shingle aging
The organic felt-based asphalt shingles shown at below left has lost some granules into the roof gutter but an inspection of the shingles themselves showed no significant bald areas. We had to look closely at those shingles in the upper right of the photo and we decided the wear was probably due to foot traffic as well.
The organic-mat asphalt roof shingle shown at right, also showing normal wear, is completely worn out, showing shingle substrate, sun and heat damage, and basically, that the roof needs to be replaced. A shingle like the one shown is usually so fragile that stepping on it breaks it into many small fragments.
These shingles (above right) may already be leaking into the roof substrate, placing water between the shingle and its felt underlayment, between the underlayment and the roof sheathing, or leaks may be entering the roof structure. Even if there is no visible evidence of leaks in the living area (such as stains on top floor ceilings or visible water in the attic) this roof is at the end of its life.
Wherever and whenever a roof shingle has lost the protection of its mineral granules that shingle has a reduced life expectancy. In all climates the loss of granules means that area of the roof shingle has lost its protection from sunlight. In freezing climates, shingle wear may accelerate in the area of lost granules as the roof ages and is exposed to freeze thaw cycles.
Below (left), the picture of bald areas in this laminated asphalt shingle or "architectural shingle" roof show white fiberglass roof shingle substrate. Our OPINION was that this was a defective roof product. This same roof also suffered thermal splitting or tearing damage (below right). Photos of roof damage below were provided by ASHI Home inspector Steve Mauer and photographed in 2009.
Our OPINION is that the asphalt roof shingle granule loss shown at below left is due to a defective product.
The shingle tearing and splitting (above right) on the same roof is also often a product defect (CRACKS in FIBERGLASS SHINGLES).
Check the shingle surface for mineral granule loss
The critical place to evaluate the condition of roof shingles is at the edge of or (if safe and the roof is not fragile), on the roof itself. Look closely at those shingles - get down on your hands and knees and look closely for early wear signs such as tiny bald spots, pits, cracks, or other damage. If you can't see obvious bald areas from which the protective granules have been lost from the shingle, it's unlikely that granule loss is a current problem.
Look in the gutters for lost mineral granules from the roof
The photograph at above left shows a modest amount of mineral granule wash-off into the gutter of this home. If the roof is a new one, this may be a normal amount of granule loss. When the gutter is cleaned out completely, you should not see this same level of mineral granules again soon. If you do, there may be a rapid wear problem going on with the roof, or someone may be dancing on it.
The photograph at above right shows a significant loss of mineral granules into the gutter on this roof. A look at the scoured surface of the roof shingles and a report by the owner of a recent and significant hail storm suggest that this granule loss may have been due to hail damage. we discuss evaluating hail damage to roofs and how to distinguish hail damage from other sources of shingle granule loss at HAIL DAMAGED SHINGLES.
Look on the ground for lost mineral granules from the roof
Check the ground surface at the end of the downspouts or roof leaders. If you see lots of mineral granules there the roof is either brand new or badly worn. A check of the roof surface easily distinguishes between these two conditions.
Extensive shingle granule loss alone, sufficient to expose the roof shingle substrate, means that the wear rate on the roof will accelerate. That's because the shingle body is exposed to direct sun and in freezing climates because the exposed shingle substrate begins to absorb water, suffering from the freeze-thaw cycle. In other words, once the shingle substrate is exposed by mineral granule loss, that area of the shingle will absorb more water than its neighbors.
When shingle granule loss is extensive or when it is combined with other roof defects (such as tears, cracks, brittle shingles that can't be walked-on for patching, or more than just a very few readily-accessible (patchable) defects, those will usually form a sound basis for asserting that the roof is already leaking (at those cracks) even if water has not appeared on finished ceilings inside the home, and they both argue that this roof has no predictable useful remaining life.
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