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Remodeling and Construction

2011-04-01 13:55:00

Roof repair from hail – series

Question: I have enjoyed your articles. I have a rather long question. I have a 13-year-old, asphalt, shingle roof. After last September’s hail storm, my roof sustained damage to the southern slopes, which I believe were perpendicular to the incoming hail. After the storm, I had over 1/2” of granules in a brand new gutter and the southern slopes were strewn with thousands of 1/8” to 3/16” pits. The underside of the shingles did not show any cracking or indentations, as would be expected I would think from hail nearly one inch and larger in diameter. I recently had an adjustor come by to look at the damage to my roof. He said my damage was due to blistering, not hail. I was on my roof 5 months prior to the storm and replaced 3 pipe boots on the southern roof slopes. The shingles never exhibited any raised bubbles at that time. They were smooth and flat. My weight did not disturb anything more than a few stones from the roof surface. The adjustor showed me a photo of burst blisters, which I have to admit, looked like my damage, but all of the research I can find indicates that 13-year old, asphalt shingles don’t suddenly develop a manufacturing or installation issue known as blistering. I say this is hail damage. What do you say?

Answer: Blisters on asphalt or fiberglass shingles should be visible in and out of the hail damage area if they were present before the storm. A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose the problem. Here is my reasoning on the question of distinguishing among simple hail damage, hail damage to a blistered roof, and shingle blister wear on a roof: You will want to survey the roof surface carefully, perhaps in the early morning or late afternoon with angled sunlight or even at dusk with a flashlight shone along the surface, in order to see what other roof blisters may be present in various areas of the roof. Then you can decide what role pre-existing blisters, even if they were not previously open or “burst,” may have played in the hail damage. We are not sure that hail will necessarily produce cracks or dents shown on the underside of asphalt roof shingles. That material, if the roof shingles are not old, dried and brittle, is resilient to impact. Cracks in my experience come with age, loss of volatiles and shingles becoming dried and brittle. Or in some cases, cracks occur from defective product. The presence of mineral granules in quantity appearing after a hailstorm and in the previously new clean gutters is a strong indication that the roof suffered granule loss during the storm. A couple of questions might be, “Were there previous blisters on the shingles and did that play a role in the granule loss?” Does that affect the shingle warranty or an insurance claim for hail damage following a hail storm?” I agree with the insurance company adjustor that shingle blisters can deteriorate to shingle pitting, and often will ultimately do so from foot traffic or just shingle aging depending on how long the shingles remain on the roof. But blisters on asphalt shingles can also convert to pitting due to hail damage, and in that case one might argue that the roof age or wear was accelerated by the hail storm that burst the blisters leaving the pits. However, if blisters were the source of pitting on your roof, one would expect to find some remaining, un-burst blisters, perhaps lower in profile. It seems to me less likely that even on a blistered roof you would get 100% blister bursting in a hailstorm. So a careful inspection should find some remaining blisters, or at a minimum, raised edges (previously blister edges) around the pits on the shingles now, after the storm. If there are no blisters on the roof shingles now, and considering that you report not having seen blisters before the storm, and since post hail we see just pits with no unopened blisters, and particularly if the pitting occurs on the slopes most impacted by the hail, hail damage sounds like a likely explanation.