How to tell a nest from lint
Timing is the giveaway. Lint builds for years and the drying time creeps up so slowly that most people only notice when a load needs two cycles. A nest goes in over a few days, so the airflow falls off a cliff.
- Chirping, scratching or fluttering from the wall or the vent hood
- Twigs, grass or straw poking out of the hood, or on the ground under it
- Droppings on the wall below the vent
- Birds landing at the same spot on the wall or roof repeatedly
- The dryer running hot with almost no air coming out outside
- A smell from the vent, which usually means something died in there
A phone camera on the hood settles it in about ten seconds if you can reach it safely. If the vent is on a roof, do not go up to look.
Why birds pick dryer vents
It is warm, dry, sheltered from wind and rain, out of reach of most predators, and it has a hood over the entrance. From a nesting point of view it is better than anything else on the building.
The part that makes it possible is almost always a damper flap that no longer closes. The flap is meant to swing shut when the dryer stops. Lint, paint, age or a bent hinge holds it open, and an open flap reads as an open door.
What it does while it sits there
A blocked vent sends the heat and moisture back down the duct instead of outside. The dryer runs longer, runs hotter, and the lint already lining the duct sits against that heat. Nesting material is dry grass and twigs packed into the hottest part of the run.
Short of that, the machine works harder than it was designed to, the laundry room gets humid, and a dryer with a thermal cut-out will start shutting itself off partway through a cycle.
What removal involves
The nest comes out physically, from the outside, through the hood. Running a brush at it first only packs it tighter and pushes it deeper into the duct, which turns a twenty-minute job into an hour.
Once it is out, the whole duct gets cleaned, because a nest sits on top of however many years of lint were already there. Then the airflow gets tested, and the hood gets checked or replaced. Skipping that last step means doing this again next spring.
If there are eggs or chicks in it
That changes what can be done and when. Many native birds are federally protected while a nest is active, and the usual answer is to wait until the young have fledged before clearing it, which is typically a couple of weeks rather than a season.
Say so when you call. In the meantime the dryer should not be run, and a vent line can be temporarily rerouted or the machine left off rather than pushing heat into an occupied nest.
What stops it happening again
A proper dryer vent cover: a hood with a working damper, or a louvered cap that closes under its own weight. That is the whole fix, and it costs less than the cleaning does.
What does not work is stapling a screen or a piece of hardware cloth over the opening. Mesh catches lint, lint blocks the vent, and a blocked vent is the problem you were trying to avoid. Anything fitted over a dryer vent has to pass lint through it freely.
Doing it yourself
On a ground-floor wall hood you can reach from a step ladder, this is a reasonable afternoon: gloves, a mask, take the hood off, pull the material out, clean the duct, put a working cap back on.
On a roof cap it is not. That is a ladder, a pitch, and a twenty-five foot vertical duct you cannot brush from below, and the cost of the visit is a great deal less than the cost of the fall.
If you are in Las Vegas
We pull these out and clean the duct in the same visit, usually the same day you call. Dryer vent cleaning across the valley is what we do, and Henderson is on the same run.
Outside the valley, look for someone who quotes the nest removal and the duct cleaning together. A price for one without the other means half a job.