Wind Damage on a Roof, and Why Age Beats the Wind Rating
A shingle rated for 150 mph can fail at 115. IBHS surveyed 1,412 homes after two hurricanes and found more than four in ten roofs over five years old damaged at relatively low gusts. Here is what wind damage looks like, and where on the roof to start looking.
The short version
Three things worth knowing first
Before the signs, because they change how you read them.
There is no mph figure at which shingles start to fail. Pages that give you a neat ladder of wind speeds are quoting themselves. IBHS, which has no stake in finding damage, publishes something more useful and less comfortable instead.
Age beats the rating. In the IBHS and University of Florida survey of 1,412 homes after Hurricanes Gustav and Ike, more than 40 percent of roofs older than five years were damaged at relatively low three-second gust speeds. Ten houses built to a fortified standard, with shingles rated to 150 mph, performed poorly in gusts that likely reached only 115.
The seal is the thing. What a wind rating measures is largely the strength of the adhesive bond between one shingle and the one below it. That bond ages on its own schedule, which is why the number on the bundle describes the roof you had rather than the roof you have.
Where to look
Why the middle of the roof is the wrong place to look
The building code does not treat a roof as one surface. Following ASCE 7, it splits it into three pressure zones: Zone 1 is the field or middle, Zone 2 is the perimeter at the eave, edge and ridge, and Zone 3 is the corners and the eave/edge and edge/ridge intersections. Wind load runs lowest in Zone 1 and highest in Zone 3.
IBHS measured damage against those zones and found the rates in the lower pressure zones were similar to or lower than the rates in the higher pressure areas. So the list below is ordered by zone, highest first. It is not a ranking of how bad each sign is. It is the order to look in.
The signs
Six signs of wind damage, by where the load is
Ordered by pressure zone, highest uplift first, then by how easily you can see it. The order is computed from those two keys, not arranged by hand.
1. Ridge cap shingles lifted or gone, the one sign worth a look after every storm
Zone 3, corners and edge intersections, highest uplift
The ridge is the long horizontal peak, and the caps are the shingles folded over it. They sit at an edge/ridge intersection, which is the highest pressure area on the roof in the code's own zoning, and they are bent over a hard line rather than lying flat. That combination is why they go first. You can usually see a gap or a cocked cap from the driveway if you know to look up at the peak rather than at the middle of the roof.
The catch. A missing cap does not leak straight away, so there is nothing to tell you it happened. It leaves the ridge vent or the nail line underneath exposed to the next rain, which is the part that does the damage.
2. Creased shingles near a rake or corner, the damage that looks like no damage at all
Zone 3, corners and edge intersections, highest uplift
Wind gets under a shingle, folds it back on itself, and the fold cracks the mat underneath. Then the shingle drops back down and reseals, and from the ground the roof looks untouched. The crease is a hairline across the tab. It is the reason two roofs hit by the same gust can be described completely differently depending on who looked and from where.
The catch. A creased shingle is a broken shingle whether or not it is still lying flat, and it is the single easiest thing to miss from the ground or from a photo taken at the eave.
3. Drip edge or rake flashing peeled back, the sign that water is already behind the edge
Zone 3, corners and edge intersections, highest uplift
The metal running along the eave and up the rake is the last thing between the wind and the edge of the deck. Along a rake it sits in Zone 3 for its whole length. Once a run of it is lifted, the wind has an opening under the first course of shingles, and rain driven sideways goes straight onto the sheathing rather than into the gutter.
The catch. This one is also the cheapest thing on the list to fix and the most likely to be left alone, because a lifted strip of metal does not look like roof damage to anybody who is not a roofer.
4. Missing shingles or tabs along the eave, the obvious one, and still the most reported
Zone 2, the perimeter at eave, edge and ridge
The eave is the bottom edge, and the perimeter around it is Zone 2: more load than the middle of the roof, less than the corners. When shingles leave, they usually leave from here or from the rake, and they usually leave in a line rather than one at a time, because each one was holding the next one down.
The catch. Count what is gone before anyone quotes you. A handful of tabs off one slope is a repair. A line of them along two slopes is a different conversation, and the difference matters for a claim.
5. Punctures and scrapes from flying debris, the damage wind causes without touching the shingles
Zone 1, the field or middle of the roof
A branch landing on a roof, or a neighbor's shingle arriving edge-on at speed, makes a hole or a gouge that has nothing to do with uplift. It lands anywhere, which is why it sits in Zone 1 here rather than at an edge, and the strike is often small and dark and easy to walk past.
The catch. Debris damage and hail damage get confused constantly, and they are not the same claim. IBHS has a separate guide to telling hail bruising apart from everything else, and it is worth reading before anybody writes either word on paperwork.
6. Shingles still in place but no longer sealed, what the research says actually decides the outcome
Zone 1, the field or middle of the roof
Every asphalt shingle has a strip of adhesive that bonds it to the course below. That seal, not the nails, is what the wind rating is really measuring, and the test for it measures the strength of the bond directly. A seal that has let go leaves a shingle that lies flat, looks fine, and lifts by hand.
The catch. This is the finding that should change how you read a wind rating. IBHS found more than 40 percent of roofs older than five years took damage at relatively low gust speeds, and ten houses with shingles rated to 150 mph performed poorly in gusts that likely reached only 115. Age beat the number on the bundle.
Send us a photo or call (984) 224-7182. We will tell you whether it needs an inspection or whether it can wait.
Wind ratings
What the classes actually mean
The published ASTM D7158 classes, as tabulated by IBHS. Fastest first.
Class
Design wind speed
Class H
150 mph
Class G
120 mph
Class F
110 mph
Class D
90 mph
Class A
60 mph
Figures from IBHS, Surviving Nature's Fury. Only the classes IBHS tabulates appear here. The rating is produced from the uplift on a tab and a direct measurement of the adhesive bond between shingles, which is why IBHS raised questions about how well it predicts performance in a real storm.
Two things follow from that table. The first is that the spread is wide enough to matter: a Class A shingle and a Class H shingle are rated 90 mph apart. The second is that the rating is a statement about a new, correctly installed shingle in a laboratory, and a roof in a storm is none of those three things.
Not wind damage
Five things that get called storm damage
Worth knowing before somebody writes the word on paperwork with your name on it.
What you are seeing
What it usually is
Granule loss spread evenly over the whole roof
Normal shedding as a roof ages. Wind strips granules in patches where it has worked at a shingle, not uniformly across every slope.
Dark streaks running down the slope
Algae. It is a cleaning question, not a storm question, and it has its own guide.
Curling or cupping across a whole slope
Age and attic heat. A wind-creased shingle is a single hard line across one tab, not a slope of shingles turning up at the edges.
Nail heads showing through the shingle above
An installation problem that has been there since day one. Wind will find it and make it worse, but the gust did not put it there.
One shingle missing in the middle of an otherwise perfect slope
Usually a nailing miss on that one shingle rather than a wind event, because wind takes neighbors with it.
There is no published speed at which asphalt shingles start to fail, and any page giving you a tidy ladder of mph figures is quoting itself. What the research does say is more useful: IBHS surveyed 1,412 homes after Hurricanes Gustav and Ike and found more than 40 percent of roofs older than five years were damaged at relatively low three-second gust speeds. In the same body of work, ten houses built to a fortified standard with shingles rated for 150 mph performed poorly in gusts that likely reached only 115 mph. The age and the condition of the seal matter more than the rating.
Can you see wind damage from the ground?
Some of it. A lifted or missing ridge cap and a line of missing tabs along the eave are usually visible from the driveway. Creased shingles and a broken adhesive seal are not, and those are the two that get missed, which is why a storm inspection that happens entirely from the ground is not an inspection. Nothing on this list requires you to get on the roof yourself.
Does a wind rating mean my roof will survive that wind speed?
Not on its own. The rating is produced by measuring the uplift on a tab and the strength of the adhesive bond between shingles, then working out a speed from that. IBHS has published doubt about how well those ratings predict real-world performance, because a roof in a storm is loaded by turbulent gusts rather than steady lab airflow, and because the seal ages. The rating describes the shingle when it was new and correctly installed.
Is wind damage covered by homeowners insurance?
Wind is normally a covered cause of loss, unlike wear and age. How much you are paid is a separate question from whether you are covered, and in North Carolina that depends heavily on whether the policy settles at actual cash value or replacement cost. We have written that up separately.
How soon after a storm should the roof be looked at?
Before the next one, and before you make permanent repairs. The NC Department of Insurance says to list the damage and take clear pictures before any temporary repairs, to do what you can to stop further damage, and not to make permanent repairs until the insurer has had a chance to inspect. Keep the receipts for anything you spend protecting the house, because those reasonable expenses are part of the loss and may be reimbursed.
Do I need a new roof if shingles came off?
Not necessarily, and anyone who tells you so before measuring has not measured. A few tabs off one slope is a repair. What pushes it toward a replacement is damage on more than one slope, a seal that has gone across the whole roof, or an age that means new shingles will not bond reliably to what is already there.
Keep reading
Related guides and calculators
Storm, hail, insurance and the inspection that settles it.
Seven signs, and the one that should not wait a season.
Free on-site inspection
Get your roof checked after the storm
We get on the roof, photograph what is actually there, and hand you a written report with a price. No charge, and no obligation to book the work with us. If the roof has years left in it, that is what the report will say.
