Range Hood Repair · Denver
The Hood Stopped Drafting After the Roofers Left: What a Denver Hail Re-Roof Does to a Kitchen Exhaust Termination
If a Wolf hood stopped drafting after a re-roof, check the termination before condemning the blower. Front Range roofs are replaced on a hail cycle, and the 8 May 2017 storm alone drove roughly 100,600 homeowner claims, by a trade whose scope is the roof.
The part of the year that matters
Late spring into midsummer is roof season on the Front Range, and roof season is when kitchen exhaust quietly stops working. Denver sits in Hail Alley, second only to Texas in insured hail losses nationally, and the consequence for housing is that roofs here get replaced on a hail cycle rather than a wear cycle.
The scale of a single event makes the point. The Front Range hailstorm of 8 May 2017 became the costliest catastrophe in Colorado history, more than doubling the previous state record, and produced roughly 100,600 homeowner claims alongside about 167,000 auto claims. That is not a rare occurrence in kind — the state normally sees several damaging hail events a year — it is just the largest recent one.
What that means practically is that a great many Cherry Creek, Washington Park, Highland and Capitol Hill roofs have been stripped and rebuilt in the last decade by crews working fast, in volume, under an insurance timetable. And every ducted hood in those houses terminates through that roof.
What the swing asks of the machine
A re-roof asks your exhaust termination to be removed and correctly put back by a trade whose job that is not. To be fair to roofers: their scope is the roof. The jack your duct passes through is, from their side of the work, a penetration to be flashed and made watertight, and watertight is the standard they are held to.
Here is the honest framing, and we will not overstate it: what follows is a list of things to check first at a Denver address after roof work, not a claim about how often any of them happen.
The termination cap can come back as a different model — a lower-profile or generic replacement that flashes beautifully and restricts more than the original. The duct can be left disconnected from, or only loosely seated on, the underside of the collar, so the hood now exhausts into the attic or the joist bay instead of outside. The backdraft damper can be taped shut for the duration of the work and never untaped, or it can be reinstalled backwards. A bird or debris screen can be added where none was fitted. Loose-fill insulation can be disturbed and end up packed against or into the boot. Any one of those changes what the blower is working against without changing the blower.
The failure it produces, and when
The complaint that reaches us is not “my roof was replaced”. It is “the fan runs but the smoke drifts into the next room”, or grease reappearing on the cabinet faces of a kitchen that never had it, or a hood that sounds exactly as loud as it always did while capturing nothing.
The timing is what hides the cause. A restriction at the termination costs delivered airflow, not noise, so nothing announces itself. The blower spins up as usual, the lights work, the controls respond. The fault only becomes obvious under real load — a hard sear, a pan of something smoky — and in most households that is weeks after the scaffolding left. By then nobody connects the two events, and the natural conclusion is that the hood is failing.
There is a related symptom worth naming because it is a safety one. If the duct now discharges into an attic or a closed cavity rather than outdoors, you are depositing warm, greasy, moisture-laden air where it should never go. Staining on a ceiling near the hood, or a smell of cooking upstairs, deserves a look under the roof rather than at the blower.
The wrong response to all of this is to condemn the motor. A blower is a straightforward thing to test, and if it draws normal current, spins freely and steps cleanly through its speeds, the machine is not the problem — the path out of the house is.
Getting ahead of it
Photograph your termination before the roofers arrive. One picture of the cap from the driveway, one from the roof if you can safely get it, and one of the duct where it meets the boot in the attic. That set of images turns a later argument into a comparison.
Then tell the roofing contractor, in writing, that the kitchen exhaust terminates through that roof, and that the cap and its damper are to be reinstated as found or replaced like for like. Ask for the cap to be left operable rather than sealed. Roofers accommodate this readily when they are told; they cannot when they are not.
The morning after the crew finishes, run the hood on high and check three things: that you can feel discharge at the cap from outside, that a tissue held under the baffles is pulled up and held, and that the damper opens. Compare that against how the hood behaved before. Five minutes, and it either closes the question or opens it while the contractor is still contactable.
While you are thinking about hail, cover outdoor cooking equipment properly for storm season. Control panels, knobs and grates take stone damage that is entirely avoidable.
What we do on the visit
We test the hood as a system rather than as a box on the wall. That means confirming the blower’s current draw and speed response, checking the baffles and filters, inspecting the damper’s operation, and then following the duct as far as it can be accessed to find where the air is actually going and what is restricting it. Where the termination is reachable, we look at it. Where it is not, we say so rather than guessing.
If the fault really is in the equipment, this site publishes its bands. Motor work — a convection fan or motor — is quoted at $290 to $660. A control board or touch panel sits between $450 and $860. Beyond the ventilation side: igniter or spark module, $180 to $460; burner valve or orifice service, $260 to $620; calibration of an oven thermostat or sensor, $190 to $440; hinge, glass or seal work on a door, $270 to $710.
If the fault is a duct or a termination that came back wrong, that is roofing and ducting work rather than appliance repair, and we will hand you a description precise enough to take to whoever did the roof. Wolf Appliance Repair Denver charges $89 for the diagnostic visit. Ring (720) 807-8323, or book through the link on this page.
Follow-ups
My hood worked before the roof was replaced. Can the two really be connected?
They can be, and it is worth checking before anything gets condemned. Your exhaust terminates through the roof, so the cap, the flashing and the duct behind them are all handled during a re-roof by a crew whose remit is watertightness. A restriction at the termination costs airflow silently: the blower still sounds normal, and the loss only appears under heavy cooking.
How can I check the termination without climbing on the roof?
Run the hood at full speed and hold a tissue under the baffles. It should be pulled up and held rather than merely fluttering. Then have somebody outside look and listen for discharge at the cap. Staining on the ceiling near the hood, or cooking smells turning up on the floor above, suggests the duct is now discharging into a cavity.
What should I tell the roofing contractor before work starts?
Put it in writing: the kitchen exhaust terminates through that roof, the cap and its damper are to be reinstated as found or replaced like for like, and the cap must be left operable rather than sealed. Photograph the cap and the duct connection beforehand. Contractors accommodate this easily when told, and cannot when nobody raises it.