Canyon Wind Takes the Edges First

Royal Dane Roofing · Salt Lake City, UT · From the roof

Canyon wind does not take the whole roof. It takes the edges first.

The morning after a real east wind event, my phone starts around six. Somebody is standing in their driveway holding a piece of ridge cap that came off the top of their house and landed in the neighbor’s yard. The rest of the roof looks untouched from the street. They want to know how wind that strong took one small strip off the peak and left everything else alone. It is a fair question, and the answer explains almost everything about how wind damages a roof.

If you live along the benches or anywhere the canyons open into the valley, you already know the wind here does not behave like wind in flatter places. Air pours down out of the canyons, compresses through the mouth, and accelerates into the valley in gusts that arrive with no warning, from a direction most roofs were never designed around. Emigration, Parleys, Big and Little Cottonwood, up through Weber Canyon. Homes downwind of those mouths take a beating a few times a year.

What that wind does to a roof is specific and predictable. Ten years on roofs, three running my own shop, and I have never once seen a wind event start in the middle of a roof plane. It always starts at an edge.

The physics are simpler than they sound

Almost everybody pictures wind damage as a shove. A big gust hits the side of the house, pushes on the roof, and something breaks. That is not what happens. Wind accelerates as it moves over the shape of your roof, and fast moving air across a surface drops the pressure above it. The pressure underneath does not drop with it. What you get is a net upward force, negative pressure pulling shingles away from the deck. It is closer to a wing generating lift than to anything being pushed.

That is why edges lose first. In the field of a roof plane, every shingle is lapped, sealed, and weighted by the course above it, and air has no reasonable way to get underneath. At the eave, the rake, the ridge and along hip lines, you have an exposed leading edge where air gets a purchase. Once a corner lifts a fraction of an inch, the wind has a lever and the force multiplies fast.

Geometry compounds it. Corners and peaks are where airflow separates and turns turbulent, and turbulence produces the highest uplift pressures on the structure. The ridge sits at the top of that gradient, which is why ridge and hip cap go first, and the outer three or four feet all the way around sees far higher uplift than anything in the middle. Roofing systems are supposed to answer that with tighter fastening at the edges. Not every roof got it. Attic pressure factors in too, which is one reason roof ventilation comes up when we talk about wind, not only summer heat.

Where the nail goes decides whether the roof holds

If I could get homeowners to understand one thing about shingle installation, this is it. Every architectural shingle has a designated nailing zone, a narrow band across the shingle at or just below the sealant strip, where the manufacturer intends the fastener to land. In that band the nail passes through two layers, the shingle being installed and the top of the one below it, and that double thickness is what gives the fastener its holding power against uplift.

High nailing means the fastener landed above that zone. The shingle is still on the roof and looks perfectly normal from the ground, but the nail holds a single layer, well up the shingle body where the pull against it is worst. When wind gets under the bottom edge, the shingle pivots on that high nail and tears itself off the head. This is the most common installation defect I find in this valley, and it is why two houses on the same street with the same shingles can take the same gust and only one loses material.

Count matters alongside placement. Manufacturers specify nails per shingle, and steeper slopes and high wind applications call for more. Using fewer is faster, saves material, and is invisible the day the crew drives away. It shows up the first real event. Drive depth is the same story. Too deep cuts the mat and leaves a slot the shingle slides out of; left proud, it holds the course above off the deck and opens a channel for wind. Correct is flush and snug. On a roof replacement this is the part I check personally, because nobody can see it afterward.

Starter strip, on both edges, without exception

Starter strip is a course laid before the first course of shingles, its adhesive positioned to bond the leading edge of that first course to the deck. It is why the bottom row does not peel up in the first gust. The eave gets starter almost universally, because a roof without it leaks immediately and everybody learned that decades ago. The rake, the sloped edges running up the gable ends, gets skipped constantly. Instead of starter the shingles are run to the edge and cut, sometimes with a bead of roof cement smeared underneath as an afterthought. That edge has no factory adhesive and no double layer for the fastener, and it sits where uplift is highest on the whole house.

That is why rake failures are so common and why they progress the way they do. Wind gets under the outermost shingle on a gable end, peels it back, and the course unzips toward the center of the roof one shingle at a time. I have pulled on a rake edge with two fingers and had six feet of a course come with it. On a properly started rake, that same edge will not move.

Same logic at the ridge. Cap shingles are individual pieces, exposed on all sides, sitting at the highest pressure point on the structure. They need purpose made cap rather than field shingles cut down where the manufacturer does not allow it, and fasteners placed where the next cap covers them. Cap is small, cheap, and the first thing wind takes, which makes it worth doing carefully.

A cold weather install is not sealed yet

This one surprises people and it matters here. The self sealing strip on an asphalt shingle is a band of adhesive that bonds each shingle to the one below it. It does not cure, it activates with heat. Sun on the roof warms the strip, it softens, the shingle above settles into it, and it sets into a bond that resists uplift across the whole plane. Install a roof in December along the Wasatch Front and that strip never gets warm enough to activate. The shingles are nailed correctly, the roof is watertight, everything is where it belongs, and the sealing simply has not happened. Until that roof sees a run of genuinely warm days it is more vulnerable to wind than the identical roof installed in July.

This does not mean you cannot roof in winter. We do it, and sometimes a roof cannot wait for spring. It means the installer has to know it and account for it, hand sealing where the manufacturer calls for it, particularly at rakes, eaves, ridges, and around penetrations. A crew that treats a February install exactly like a June install leaves you exposed for a few months and probably will not mention it. It also explains a pattern I see every spring: a roof installed the previous winter takes a March wind event and loses shingles, and the homeowner cannot understand how a brand new roof failed. It usually did not fail. The first big blow just arrived before the first warm stretch did.

What to look for from your own driveway

After a wind event, please stay off the roof. A roof just worked over by wind can have lifted shingles and loose debris in places you cannot see, and the fall is the real hazard, not the roof. Everything worth checking, you can check from the ground.

Start at the ridge line and sight down it. It should be dead straight and uniform. Gaps, a section sitting lower, or caps visibly cocked mean the ridge took a hit. Then work the rake edges on the gable ends for shingles lifted or standing away from the plane, and scan the field for missing tabs, which show up as a lighter rectangle where the underlayment or the shingle below is exposed. Look at the ground too. Shingle pieces in the flower beds, cap fragments, a pile of granules where the downspout empties. And note any limbs that came down, because a limb dragged across a roof does damage separate from the wind itself.

Here is the one that costs homeowners the most by getting missed. A creased shingle. Wind lifts it, folds it back on itself, and it lies right back down looking fine. But the mat inside is fractured along the fold and the sealant bond is broken, both permanently. That shingle will admit water at the crease and it will be the first to leave in the next event. From the ground a crease reads as a faint horizontal line, often catching light differently than its neighbors. It is genuinely hard to see, which is why a real inspection means getting up there. Our wind damage page walks through what we document when we do.

The clock on a claim, and why we tarp

If the damage is significant, the timing is worth understanding before you start making calls. Policies require prompt notice of a loss and usually set an outer deadline for filing after the event. Those deadlines are real, and the practical problem with wind is that damage often is not obvious until the next heavy rain, by which point weeks have passed and the date of loss is harder to establish. That is why I tell people to get the roof looked at after a notable event even if nothing looks wrong from the street. Dated photos taken close to the event are worth a great deal if you file later. Our insurance claims page explains how we work with adjusters.

On tarping, let me correct something homeowners assume. A tarp is not a contractor stalling or a placeholder to keep you waiting. Most policies obligate you to take reasonable steps to prevent further damage after a loss, and a properly installed tarp is exactly that step. Beyond the paperwork, it keeps water out of your insulation, drywall, and framing, which is the damage that costs far more than the shingles ever did.

What a tarp is not is a repair, and it should not sit for a season. It buys time to do the work correctly, whether that is shingle roof repair on a limited area or something larger. Some wind events produce a small localized repair. Others do enough damage across enough of the roof that piecemeal patching is the wrong call. We look, we show you the photos, and we tell you which one it is. I would rather be honest about a small job than talk you into a big one, and I am not the biggest shop in the valley, which means every roof I put my name on matters. Full storm damage details are on our site.

Quick Answers

Only a few ridge caps came off. Is my roof still okay?

Possibly, but the ridge is the most exposed line on your roof and losing cap means wind found a way in at the top. What matters is whether field shingles below the ridge got lifted and creased in the same gust, because that damage lies back down flat and is nearly invisible from the ground. Replacing caps without checking the courses around them is how a small event becomes a leak next spring.

How fast does wind have to be to damage shingles?

Lower than most people expect, and it depends far more on the roof than the number. A properly installed roof with sealed shingles and correct nailing handles serious gusts routinely. A roof with high nailing, no rake starter, or shingles that never sealed loses material in wind that would not bother a healthy roof. Installation quality decides it more than wind speed does.

A shingle is folded over but did not come off. Does it need replacing?

Yes. When wind folds a shingle back on itself the fiberglass mat fractures along the fold, and the sealant bond will not re bond. It may look flat again a day later, but it is a failed shingle. It will let water through at the crease and it will be the first piece to leave next time. Adjusters recognize creasing as damage when it is documented properly.

Should I go up and look at the roof myself after a storm?

Please do not. A roof that just took a wind event can have lifted shingles that give way underfoot and slick spots from rain or granule loss. The fall is the danger, not the roof. Everything genuinely useful, the ridge line, rake edges, missing tabs, granules in the gutters, debris in the yard, is visible from the ground. Do that part, take photos, then call somebody.

Will my whole roof need replacing after a wind event?

Often not. Plenty of wind damage is localized to one slope or one edge, and a targeted repair is the right answer. What pushes it toward replacement is damage across multiple planes, an older roof where matching shingles is no longer realistic, or a defect like high nailing that means the rest of the roof keeps failing. I show you photos and tell you which one you are in.