Crete flue full of nesting material: what heavy tree cover does to an uncapped chimney
There was no cap on this Crete chimney, and the flue had been collecting whatever the trees and the birds put into it for years. We took out most of a bucket before the brush went in.
What came out of it
The smoke shelf is the ledge behind the damper, and on an uncapped chimney it works like a gutter trap. On this one we cleared old nesting material, a compacted layer of leaf litter, several twigs the length of a forearm, and the remains of two acorn caches. None of it was recent. It had been going on long enough to form distinct layers.
The owner had not noticed a problem because they lit maybe six fires a winter and the flue was still passing enough air to get away with it. That is the usual story. A partly blocked flue does not announce itself until a cold, still evening when the smoke has nowhere to go but the room.
Crete’s trees are the whole explanation
Crete has far heavier mature tree cover than most of the villages we work in, with a lot of oak on the older residential lots. That means two things for a chimney. Leaf and acorn fall drops directly onto the stack rather than blowing past it, and the canopy keeps the brickwork shaded and slow to dry after rain.
It also means more wildlife traffic at roof level. Squirrels use an open flue as a ready-made cavity, and chimney swifts are drawn to tall, unlined shafts. If the flue is open at the top, something will eventually use it, and in a wooded neighbourhood that happens in one or two seasons rather than ten.
A cap is the cheapest chimney component you will ever buy
A stainless cap with a properly sized mesh keeps the rain, the leaves and the animals out, and it is a fraction of the cost of the crown repair that follows years of water getting in. The mesh size matters: too coarse and small birds get through, too fine and it blocks with soot. We fit caps sized to the flue rather than a universal cover wedged on.
Timing matters too. We would rather clear and cap outside nesting season, and autumn is a good window for exactly that reason. If your stack has nothing on top of it, that is the single most useful thing to change before winter. Our pricing page lists what a sweep and a cap start at.
If this sounds like your house: we handle chimney sweeping across Kankakee County, and our Crete page covers what we usually find there. Call (815) 449-4264, 7am to 9pm, any day.
Quick questions
How do I know if something is nesting in my chimney?
Scratching, rustling or chirping that moves when you knock on the firebox, debris appearing on the damper, or a sudden smoky smell with no fire lit. A torch up past the damper often settles it.
Can you just put a cap on without sweeping first?
We would not. Capping a flue that already has debris in it seals the problem in. The flue gets cleared and inspected, then capped.
Is it legal to remove a nest?
Timing matters, and some birds are protected while nesting. We clear outside the nesting season wherever possible, which is one reason autumn work suits this job.
How often does a lightly used fireplace need sweeping?
The trigger is buildup rather than the calendar, but a flue under heavy tree cover needs looking at yearly regardless of how many fires you light, because the debris arrives whether you burn or not.
Published October 28, 2026 · By Jacob Dove, Friendship Chimney Sweep, Bourbonnais IL