What the Santa Anas Actually Do to a Roof

After a strong Santa Ana event we get two kinds of call. The first is straightforward: shingles are in the garden. The second is the one that costs people money, and it comes in January, when the rain finds a path that the wind opened up in October.

How wind actually lifts a roof

Wind does not push a roof off. It pulls. Air moving across the roof surface creates lift, the same principle that gets an aircraft off the ground. The pressure is not uniform either. It concentrates at edges, at corners, along the ridge and at any point where the surface changes direction.

That is why damage clusters at the perimeter. The middle of a roof plane is the calmest place on it.

The seal strip problem

Here is the part homeowners rarely know. Architectural asphalt shingles are not only nailed down. Each one carries a strip of adhesive that bonds it to the course beneath, activated by heat after installation. That bond is a large part of what holds a roof together in wind.

A strong gust can break that seal without moving the shingle far enough to notice. It settles back. From the ground the roof looks untouched. But the shingle is now a flap rather than part of a sealed surface, and the next wind works it harder, and the rain after that runs underneath.

This is the single most under appreciated form of wind damage, and it is exactly the kind that a ground level glance cannot find.

What to look for from the ground, safely

Please do not climb up. From the driveway or the garden you can still check for:

• Granules in odd places. A build up at the bottom of downspouts, or dark grit on paths. Some loss is normal over years. A fresh pile after a wind event is not.
• A line that is no longer straight. Look along the ridge and along each edge. Roofs are built to straight lines, so a wave or a step stands out.
• Shingles sitting slightly proud of their neighbors, especially along the edges.
• Displaced or lifted flashing around the chimney, vents and anywhere two roof planes meet.
• Debris on the roof. A branch that landed hard may have cracked something under it.
• Gutters pulled loose at the fixings.

Inside the house

Go into the attic with a torch on a bright day and look up. Daylight where there should not be daylight is the clearest signal you will get. Look also for damp marks on the underside of the deck and darkened timber around nails.

The timing trap

The gap between wind and rain in Southern California is often months. Wind damage in October produces a ceiling stain in January, and by then the connection is not obvious. People assume the roof simply failed.

If we have had a serious wind event and your roof has some age on it, an inspection afterwards is cheap insurance. It is also much easier to document a wind related claim close to the event than months later.

Which areas take the worst of it

Santa Ana winds accelerate through canyons and passes, so exposure is not even across the Valley. Homes near the canyon mouths and on exposed slopes take more punishment than sheltered streets a mile away. Communities such as Chatsworth, Porter Ranch, Sylmar, Tujunga and Santa Clarita tend to see it first and hardest.

If your roof has been through a rough season, our roof repair team can tell you whether you are looking at a small fix or the start of a bigger conversation. Most of the time it is the small fix, and it is far cheaper handled before the rain arrives.