A roof-mounted attic fan or exhaust hood is a small piece of metal with a lot of exposed surface, and it sits on the roof where nobody looks during a storm walk. It is set on the upper part of a slope, which is often the side that catches the most hail, and it usually reads as part of the roof rather than as a separate item. If you have one, add it to your storm file before the next front comes through, because it takes hail the same way the shingles do.
Why the hood gets missed
Most owners look at the shingles and the gutters from the driveway, then go inside. The hood is up on the slope, often behind a ridge or beside a chimney, so it is out of sight from the ground. A dented cap, a cracked louver or a bent guard does not always show from below. Walk the slope where the hood sits, and look at it straight on, with the sun behind you if you can manage it.
The hood also gets missed because it is not on most checklists. Owners who know to photograph the vent caps and the chimney cap often skip the hood entirely. The hood is worth the same few minutes as those items.
Photograph the hood before anyone touches it
Take the photos from three distances. First, a wide shot that places the hood on the slope, with a ridge line, a chimney or the edge of the roof in the frame so the location is clear. Second, a middle shot of the hood itself, showing the housing, the cap and the flange where it meets the roof. Third, a close shot of any dent, crack or split, with a tape measure or a coin beside it for scale.
Shoot in daylight and keep the original files on your phone or camera rather than screenshots. Screenshots lose the file details that someone may want to check later. If you can, shoot the same spots again after any repair so the before and after sit side by side.
Count the dents on the hood cap and note which side they are on. Dents on the side that faces the storm track are a different story from dents spread evenly around the cap. A round dent in thin metal that has not cracked the paint is one kind of problem. A split seam or a crack that runs through the housing is another, and the difference matters when someone reads the file later.
What to check from the attic side
Go into the attic with a flashlight and look at the hood from below. Check the area around the pipe or the curb where the hood meets the deck. Look for daylight around the edges, for fresh staining on the sheathing, and for wet insulation directly under the opening. A hood that took a hit can split its gasket or open a gap at the flange, and water can run down the pipe into the attic without showing on a ceiling below.
Do this check on a dry day. A damp attic makes staining hard to judge, and a stain that looks new may be old moisture that was never dried. If you see a dark ring around the pipe or a patch of matted insulation, photograph it with the flashlight angle recorded in the frame, and write the date beside the photo.
Powered fans need an electrician, not a quick look
If the fan is powered, the wiring runs from a switch in the house to the motor in the attic or at the hood. Do not touch that wiring yourself. If you need to work near it, turn off the breaker that supplies the fan, confirm the fan is dead, and leave any connection work to a licensed electrician. A fan that was wet or struck by hail can short, and the risk is not worth a shortcut.
Note in your file whether the fan ran normally before the storm, and whether it hums, rattles or vibrates now. A fan that vibrates after a hit may have a bent blade or a loose mount. Either one is a repair for an electrician, or for a roofer who is working with one, and neither should be left running until someone has looked at it.
The shingles around the hood tell you whether it leaked
Look at the shingles directly around the flange. Hail that dents a hood can also crack or lift the shingles under and beside its flange, and those shingles are part of the repair. A missing or lifted tab right at the hood is easy to overlook, because the hood covers the flashing and the shingles around it are often pushed out of line by the same impact.
If a shingle around the hood is cracked, mark it in the photos and say so in the written scope. A repair that swaps the hood but leaves a lifted shingle beside it has not finished the job, and the next wind will find that shingle first.
Repair the hood, or replace it
A hood with a small dent and an intact flange can often stay in place. A hood with a split seam, a broken louver, a cracked housing or a flange that has lifted off the deck usually needs to come off and be replaced. The question that decides the scope is whether the flashing and the curb under the hood are still sound.
If the curb is soft or the flashing is bent, the hood is the smaller part of the work. Ask the roofer to say, in writing, which of these applies to your roof, and to show the flashing under the hood in a photo, not only the hood on top. A photo of the flashing with the hood lifted is the record that shows what was there before the new hood went on.
Why the cold months raise the stakes
Late October in St. Louis is when the nights start to drop below freezing and the days stay mild enough for the freeze and thaw cycle to begin. Water that gets past a split flange or a cracked gasket can sit in the gap around the curb, freeze, and widen the opening a little more each time it thaws. A hood that leaks a few drops now can leak a steady stream by midwinter.
That is one reason to get the hood photographed and written up before the cold settles in, rather than after the first ice event. A dry day with the roof surface cool and dry gives the clearest photos, and it leaves time for a repair before the first hard freeze.
What to ask your roofer about the hood
- Is the hood listed as its own line in the written scope, or folded into the shingle price?
- Will the crew lift the shingles around the flange and photograph the flashing underneath before the hood goes back on?
- If the fan is powered, who disconnects it, who reconnects it, and is a licensed electrician named on the bid?
- What is the replacement hood's make and model, and will that same model appear on the invoice?
- Will the photos of the hood, the flange and the attic side reach you as original files, not as screenshots or a summary?
Keep the hood in the file
The hood belongs in the same folder as the shingle photos, the vent cap photos and the chimney cap photos, with the same date stamps and the same written notes. Keep the attic photos in that folder too, since they show whether any water reached the deck. If a repair happens, keep the before and after photos together, and keep the invoice that names the hood. Those papers are yours to hold, and they are the ones that tell the story of the roof after the storm, whoever you end up sharing them with.