Jason,

Everytime it rains there is granule loss from the shingles, along with walking on the roofs, hail of any size, etc. i do not know of wind alone removing granules, unless it was in conjunction with tabs that are loosened and blowing up/flapping in the wind. I lived there in Houston for about 13 years and you will get some heavy rainstorms with large drops of rain that can loosen granules a fair amount. After every big rainstorm I'd see more granules on the ground around my downspouts. Also keep in mind that in Houston the sun is a lot more brutal on roof surfaces then in a place like Omaha. A 25 year roof in Houston may last 15-18 years at best, and by that time there is severe wear and tear on the roof. A 25 year shingle where I grew up in Illinois would last 30 years or better. I've dealt with the loss of "useful life" claims a fair amount and never paid for a roof under that theory. You can run into roofs that have 'sections" of shingles that have a higher degree of missing shingles, and almost every time that can be related to a bundle or two that is put on the roof that may have product defect to it. You can always tell if that is the case as these are all grouped together in smaller sections on the roof. If the roof is under warranty still, the manufacturer can verify that is the case and they will stand behind the shingle. I don't have pictures of this type of thing, but if someone does it might be helpful if they can post them.

Granular loss is a natural progressive happening on any shingle.  The general rule of thumb is that about 30% of the make-up of a shingle is granular weight.  On a 240 3-tab shingled roof, that means 80 lbs of granules per sq.  When Mr insured showed me the 4 lb coffee can full of granules that he swept up from the 4 corner downspouts, I offered to take a pail up with me & scoop in the granules that were in the gutters.  If there were no hail hits observable on his 20 sq roof (1600 lbs of granules), I explained we probably needed to come up with at least 160 lbs or about 4 five-gallon buckets full of granules to convince the carrier it was hail damage. Putting it terms like that helps your average homeowner understand it better. (until their neighbor across the street with the 27 yr old roof gets it totalled out & replaced)

Jason,
Steve is correct, those granules have been migrating from the roof since the day the shingles were installed. In the Houston area, in large part since 1983, shottly after Hurricane Alicia. Hmm, 25 year roof, 1983-2008, 25 years since Alicia. Go figure. Can a shingle which has served its full useful life expectancy be degraded/deteriorated by a windstorm which does not otherwise compromise the shingle? The age old question surfaces: Can a worn out roof (which needed to be replaced anyway) become damaged in a wind/hail event? If so, what is the monetary extent of such damage. The insurance claims industry position has been that if a roof was performing it's intended function (repelling water) prior to the occurrence, then indeed it had some useful life remaining. The question becomes: did this occurance alter its function.

Absolutely correct.  Jason didn't mention anything regarding blown off tabs, lifted & broken seals...just granular loss.  Comes down to pre-loss condition, if that can be determined...and I think it can in many roof cases if wind only is involved.

Posted By Jason Wells on 29 Oct 2008 10:05 AM

...that have a large portion of the granules missing, fear not if I look I can find them they are in the gutters and at the bottom of the down spouts in the grass or splash blocks... 

One thing that I have really enjoyed is that I am learning new things everyday. Today is no different you have all taken the time to answer my question and in doing so have made me much wiser about an area that I was completly off base in. Thanks again.

Jason

Lightning loss to out side condensing unit during a hurricane. Very small % but a good talking point. Some time all the flaws in the house appear to be caused by hurricane winds, fogged up windows, diagonal crack in dry wall over doors windows, cracks in tile floors, foundation movement, electric problems etc. It takes good education on these complaints to discuss and move on to the covered wind damage that is not that difficult find, or not to find. Where are the codes for the scopes in the most used software. ?

hmm, do they know something that I should know, these issues need to be explained to settle these issues and keep the insured happy ?

Posted By Jason Wells on 29 Oct 2008 10:05 AM

... my storm office is declining coverage and says granular loss is not wind storm damage...

In order to determine how many granules, if any,

must be removed in order to affect the service life or

water shedding ability of the shingle, the authors' firm

conducted a granule loss study on asphalt shingles.

Varying quantities of granules were removed with a

wire brush from new, three-tab, glass-fiber mat

shingles. The shingles then were exposed naturally

to the weather in Dallas, Texas for a period of ten

years. The quantities of granules removed were

none (control), and approximately 6, 15, 45, and 70

percent of the total granules on the shingles. Another

shingle was installed upside down such that the

asphaltic mat was exposed to the weather. The

shingles were installed conventionally over a plywood

deck on a 4:12 pitch that faced south. The shingles

were examined at intervals throughout the ten year

period as well as at the conclusion of the study

In one year, the exposed asphalt had oxidized

grey but there was no visible evidence of surface

cracks or erosion. After five years, areas of exposed

asphalt had oxidized but this did not affect the

function of the shingles to shed water. Surface

erosion was visible on the shingle without granules,

and some of the glass fibers had become exposed.

After ten years, no significant change was noted in

the shingles except for the shingle without granules.

More glass fibers were exposed on this shingle due to

erosion; but, the shingle continued to shed water

The quantity of granules lost from the roof shingles

during a hailstorm is a relatively small amount.

Generally, about one-third the weight of an asphalt

shingle is granules such that a 25 square roof

covered with three-tab shingles would have about

one ton of granules. Granule loss is expected from

the moment shingles are manufactured, shipped,

installed, and during the weathering process.

Granules are part of the wearing surface on the

shingle and exposure to hail is part of the wearing

process that is actually built into the design. Thus,

more granules are initially placed on the shingles

than needed to cover the mat.

In our study, we found between 12 to 15 percent

of the surface granules had to be removed from new

shingles before the asphaltic mat was exposed. The

amount of "excess" granules on new shingles varied

by plus or minus ten percent. We would expect that

the quantity of granules lost during a hailstorm

generally would fall within the normal variation of

granules placed on a shingle.

Therefore, it seems logical to conclude that the

small quantities of granules removed from shingles

during a hailstorm does not shorten the life of the roof

or adversely affect its water shedding ability as long

as the impacted areas are not bruised or punctured,

and remain covered with granules. This conclusion

agrees with the work done by Morrison (1999).