Hail damage to many areas of the home will be obvious. Metal siding, fascia and window wraps will be dented. Vinyl siding can be chipped or cracked by hail. Screens will be torn, air conditioner fins will be flattened, paint will chip, wood can be dented or pock-marked. Damage to an asphalt roof can be much less obvious and therefore it will be much more challenging to determine to what extent the roof has been effected.
What is asphalt roof hail damage?
The first step in understanding how hail affects a roof is to understand how an asphalt roof shingle is made. The shingle starts with a fiberglass mat. The mat is coated on both sides with a layer of asphalt, which is what makes the shingles waterproof. Colored ceramic granules are applied to one side, which are held in place by asphalt. The granules, obviously, give the shingle its color, but are actually there to do a more important job. They protect the asphalt in the shingle from the sun's ultra-violet (UV) radiation. Over time, this radiation deteriorates asphalt, essentially burning it away to nothing.
When damaging hail impacts the shingle it "bruises" it. While the shingle may appear to be intact, what has happened is that the fiberglass mat that holds the shingle together has been broken and the structure that was holding the granules in place has been compromised. As time passes, as rain washes over the "bruise," as snow melts off the roof, the granules will wash out of the affected area, leaving it vulnerable to the UV rays, which will cause the asphalt in the area to shrink and decay. What is left is essentially a hole in the shingle. Depending on the conditions, this process may take weeks, even months, but it will happen eventually.
How does the insurance company determine if a damaged roof warrants replacement?
One hole in a shingle is actually not as serious as it sounds. Every shingle is layered over the top of another shingle and there are water-resistant underlayements under the the shingles. If a roof suffered only a single hail strike there is a pretty fair chance it would never leak. However, when a roof has suffered dozens, if not hundreds of hail hits, the odds reverse to an almost certainty that one or more of the affected areas will leak water into the home.
To determine how seriously a roof has been affected, the insurance company tries to measure how many hailstones did actually strike the roof. This procedure is known as a "Test Square." Basically, it involves drawing a 10'x10' square on each slope of a roof and counting the number of damaging hits in that area. This is also where the entire process gets a little fuzzy.
First, there is a wide inconsistency amongst adjustors as to to what constitutes a damaging hit. Probably the best and most accepted definition is an area that suffered granular loss, the fiberglass mat has been broken and the area appears to have been damaged by hail as opposed to something else.
Second, there is inconsistency amongst insurance companies as to how many damaging hits are required in the Test Square to approve that slope for replacement. This is due to differences in what the insurance companies call their "Repair Factor." This is a calculation to determine at what point it becomes more cost effective to replace an entire slope rather than to just replace the individual damaged shingles. There is also a Repair Factor to determine at what point it is more cost effective to replace an entire roof rather than just the slopes that met the criteria in the Test Square. Usually, if half of the slopes meet the criteria the adjustor will approve the entire roof for replacement.
Is all the hail the same?
There are a number of factors that influence how severely hail will affect a roof. The first is the hail itself. How big was it? Was the hail hard or soft? Even large hail won't damage a roof it if it just disintegrates on impact. Hail can have jagged edges or it can perfectly round. Was the hail being driven by strong winds? This can make any size hail serious.
Many factors of the existing roof will change how hail affects it. How steep is the roof? Which way are the slopes facing? Generally, the more squarely the hail impacts the roof, the more serious the damage will be. What was the condition of the roof before the hail fell? The worse the condition of the roof, the more hail will affect it. Other factors might involve trees or other buildings protecting the roof. It is entirely plausible that two houses in the same area could be affected differently by the same hail.
How much is enough?
It is very difficult to determine how any insurance company and especially how any individual adjustor will interpret the same findings on any given roof. If there is any evidence of hail damage at all or if your home is in area where you are certain that hail fell, it is in your best interest to get it checked out by a contractor who specializes in insurance restoration work.