Chimney Caps and Crowns in Geneva, IL
The two things at the very top of the chimney that keep everything below them dry. Both are cheap compared with what they prevent, and both are routinely missing or broken.
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Cap and crown are not the same thing
People use the words interchangeably and they are completely different parts. The crown is the concrete or mortar slab covering the top course of brick, sealing the masonry around the flue opening. The cap is the metal lid and mesh screen sitting over the flue opening itself. The crown keeps water out of the brickwork; the cap keeps water, animals and embers out of the flue.
A chimney missing its cap is an open pipe into your house. Rain goes straight down it onto the damper and smoke shelf, where it rusts the damper solid and soaks the masonry from the inside. It is also, to a raccoon or a chimney swift, an obvious place to nest.
What a cap does
Keeps rain out of the flue
Water landing on the smoke shelf rusts the damper, degrades mortar and mixes with creosote to produce an acidic sludge.
Keeps animals out
Squirrels, raccoons and birds nest in open flues every spring. A nest is a total blockage, and blocked flues push carbon monoxide indoors.
Stops embers landing on the roof
The spark arrestor mesh is the whole point of the screen. Relevant on any wood-burning system with a shingle roof.
Helps with downdraft
A correctly sized cap can reduce wind-driven downdraft that pushes smoke back into the room on gusty days.
Why builder crowns fail early
A crown should be cast concrete, sloped to shed water, and it should overhang the brick by an inch or two with a drip edge cut into the underside so runoff drops clear of the masonry instead of running down the face of it. It should also have an expansion joint around the flue tile, because the tile and the crown expand at different rates.
What actually gets built on most houses is a thin skim of ordinary mortar, flush with the brick, no overhang, no drip edge, no expansion joint. Mortar is not concrete and it is not a weather surface. It cracks within a few years, water runs directly into the top of the wall, and the freeze-thaw damage starts at the top and works down.
Fine surface cracking can usually be resurfaced with a flexible crown coating — a genuinely good outcome for not much money. Once the crown has cracked structurally or broken into pieces, it needs cutting off and recasting properly. We will tell you which one you have, with photographs.
Starting prices are on the pricing page. Crown failure is usually discovered during a chimney inspection, and often alongside flashing or tuckpointing work.
Missing a cap, or seeing cracks up top?
A cap is one of the cheapest pieces of protection on a house. Call and we will look.
Cap and crown questions
How do I know if my chimney has a cap?
From the ground with binoculars you can usually see whether there is a metal lid over the flue opening. If the top of the chimney looks like an open square hole, there is no cap. We check it as standard on any inspection.
What is the difference between a cap and a crown?
The crown is the concrete slab covering the top of the brickwork. The cap is the metal lid and screen over the flue opening itself. Different parts, different jobs, and a chimney needs both.
Can a cracked crown be repaired instead of replaced?
Often yes. Fine surface cracks can be sealed with a flexible crown coating that stays elastic through freeze-thaw. Structural cracks or a crown broken into sections needs recasting.
What material should a chimney cap be?
Stainless steel for longevity, or copper where appearance matters and budget allows. Galvanised caps are cheapest and rust out fastest. On an Illinois roof, stainless is the sensible default.
There is an animal in my chimney. Can you help?
We can cap the flue once it is empty, and if there is an active nest with young in it that means waiting until they leave — there are legal protections on some birds. We will be straight with you about timing rather than sealing something in.
Will a cap stop my chimney smoking?
Sometimes. If smoke rolls back into the room on windy days, a correctly sized cap can genuinely help by disrupting downdraft. If the fireplace smokes in still conditions, the cause is elsewhere — buildup, flue size or house air pressure.
Do gas fireplaces need a cap?
Yes. A gas flue is just as attractive to nesting animals and just as vulnerable to rainwater, and a blocked gas flue is a carbon monoxide problem.
How long does fitting a cap take?
A standard single-flue cap is usually well under an hour once we are on the roof. Multi-flue caps and custom sizes take longer and sometimes need fabricating to fit.
Written by Rick Lee, owner of Zenith Chimney Service in Geneva, Illinois. 19 years in the chimney trade.
Published August 27, 2026