Direct answer: If rats chewed a range hood duct, treat it as more than a torn vent pipe. First make sure the hood is off, check whether the damage is only on an exposed section, and look for droppings, nesting, grease-soaked insulation, or an open path into the wall or attic. A short exposed duct section or exterior wall cap can sometimes be replaced, but hidden contamination or structural access damage is usually a pest-control and vent-repair job.
Most likely: Most often, rats get in through a failed exterior vent cap or loose duct joint, then chew thin flex duct or foil sections near the hood or in the attic.
Range hood duct damage is a dirty repair, not a cosmetic one. If the duct is torn, crushed, or contaminated, the real job is closing the entry path and restoring a smooth, sealed exhaust run. Reality check: once rodents have been inside a greasy vent line, there is often more damage than the first visible hole. Common wrong move: stuffing the hole with steel wool without fixing the vent cap or replacing the damaged duct section.
Don’t start with: Do not start by taping over a chewed hole and calling it fixed. That leaves grease, odor, and an entry point in place.
You can see a torn foil or flex section above the hood, in a cabinet chase, basement ceiling, or attic.
Start here: Start by confirming whether the damage is only on that exposed section or continues to the wall cap or hidden run.
You hear scratching, smell urine, or get a stale greasy odor when the hood runs.
Start here: Start by treating it as possible active infestation or contamination, not just a duct patch job.
Steam and cooking smoke linger, and the hood sounds normal but exhaust is weak outside.
Start here: Start by checking for a crushed, blocked, or partially collapsed duct where rats chewed or nested.
The exterior flap is missing, stuck open, or the cap is loose with chew marks around it.
Start here: Start there, because that is often the entry point and the reason the duct got damaged farther inside.
Rats usually need an easy entry point first. A broken flap, missing screen where appropriate, or loose cap lets them reach the duct run.
Quick check: Look outside for chew marks, a flap stuck open, gaps at the siding or masonry, or a cap pulled away from the wall.
Thin duct material tears easily once rodents get into the run, especially near bends or where grease has softened the surface.
Quick check: Follow any accessible duct section and look for ragged holes, crushed spots, loose tape, or sections that sag instead of holding shape.
Even if the hole is small, nesting material can choke airflow and hold odor inside the line.
Quick check: Run the hood briefly and check outside for weak discharge. If airflow is poor and you see debris near a tear or cap, assume blockage until proven otherwise.
Droppings, urine, and grease can spread along insulation, cabinet chases, attic surfaces, and hidden duct sections.
Quick check: Look for staining, droppings, shredded insulation, or odor that extends beyond the torn spot. If you find that, the repair is bigger than one duct patch.
You do not want to disturb a live nest or spread contaminated dust before you know what you are dealing with.
Next move: If you confirm this is old damage only and there is no sign of active rodents, you can move on to checking how much of the duct is affected. If you find fresh activity, stop disturbing the area and arrange pest removal first. Repairing the duct before the animals are gone usually gets you right back to the same problem.
What to conclude: Active pests change the job from a simple vent repair to containment, cleanup, and entry-point correction.
The outside opening is usually the real failure. If that stays open, a new duct section will not last.
Next move: If you find a failed wall cap or one clearly damaged duct section, you now have a likely repair target. If you cannot identify the entry point or the run disappears into finished spaces with odor or debris still present, this is a better pro job.
What to conclude: A visible entry point supports a focused repair. No visible entry point usually means hidden damage, a roof termination issue, or a larger pest path nearby.
A short accessible tear can be a parts repair. Contaminated insulation, hidden nesting, or multiple damaged sections usually is not.
Next move: If the damage is limited to one exposed section with clean surrounding surfaces, replacement of that section and the failed cap may be reasonable. If contamination extends into insulation, framing cavities, or hidden runs, bring in pest cleanup and vent repair help instead of trying to patch around it.
Once the damage is clearly limited and accessible, replacement is more reliable than patching chewed, greasy duct material.
Next move: If the new section fits cleanly, the cap closes properly, and the run is sealed and supported, you are ready to test airflow and odor. If the replacement path requires opening walls, changing the duct route, or dealing with multiple hidden damaged sections, stop and schedule a vent contractor or qualified handyman with pest cleanup support.
A repaired duct still has to move air well, close up tightly, and stay odor-free. That is how you know you fixed the cause, not just the hole.
A good result: If airflow is strong, the flap works, and no new odor or activity shows up, the repair is likely complete.
If not: If airflow is still weak, odor remains, or new activity appears, move to professional vent inspection and pest exclusion. There is likely hidden blockage, contamination, or another access point.
What to conclude: Good airflow and no returning signs mean the duct and entry point were the real problem. Persistent odor or weak exhaust means there is still damage or contamination farther along the run.
Repair Riot may earn a commission from qualifying purchases, at no extra cost to you.
Not as a real repair. Tape may cover a small hole for the moment, but it does not remove contamination, fix a crushed section, or close the outside entry point that let the rats in. If the duct is chewed and dirty, replacement is usually the better move.
It can be. Kitchen exhaust ducts carry grease and hot cooking vapors. A torn or disconnected section can leak greasy air into cabinets, walls, or attic spaces. It is not something to ignore.
If there is any sign of active rodents, yes. Fixing the duct first often fails because the animals are still inside the area or still using the same access path.
Usually yes if it is damaged, loose, or not closing properly. That cap is often the original entry point, so leaving it in place can undo the rest of the repair.
That usually means contamination or blockage remains farther down the run or in nearby insulation and framing. At that point, a deeper vent inspection and cleanup is the right next step.
Light old residue on an exposed section may be manageable with proper protection, but heavy droppings, urine, nesting, or contamination in hidden spaces is better handled by pest cleanup and vent repair pros.