The cap and the crown are the two things standing between the inside of your chimney and the weather. They are also the cheapest parts of the chimney and the ones most likely to be missing. Chimney Sweep Bros fits stainless caps and rebuilds cracked crowns across Orland Park and the Southwest Suburbs. It is the single highest-value maintenance job on a chimney, and we are insured and reachable seven days a week on (708) 432-3430.
Cap and crown are not the same thing
- The crown is the sloped concrete or mortar slab on top of the chimney stack. It covers the brickwork and sheds rain away from the flue. It should overhang the brick with a drip edge, and it should be poured concrete — not a thin skim of mortar, which is what a lot of chimneys have and why so many crowns crack.
- The cap is the metal lid over the flue opening itself, with mesh sides. It keeps rain, snow, birds, squirrels and leaves out of the flue while still letting smoke out.
What happens when they are missing or broken
An open flue with no cap is a hole in the roof. Rain and snow fall straight down onto the damper and the smoke shelf, where they sit against metal and masonry. Over a few seasons you get a rusted damper that will not close, a saturated smoke chamber, that unmistakable damp-soot smell in the room, and mortar joints inside the flue quietly dissolving.
A cracked crown does the same thing more slowly and more expensively. Water runs through the crack into the gap between the flue liner and the surrounding brick — the one place you cannot see and cannot dry out. It freezes, expands, and pushes the chimney apart from the inside. Nearly every case of spalling brick and failed mortar we are called out to starts here.
The animal problem, specifically
An uncapped flue is an ideal nesting site: warm, sheltered, and vertical. Squirrels, raccoons and chimney swifts all use them. A nest is a complete blockage, which means the next fire you light pushes smoke and carbon monoxide back into the room rather than up the flue. We pull nests out of uncapped chimneys in Orland Park every year, and every one of them was preventable with a cap.
What we fit
- Stainless steel caps. Galvanised caps rust out and have to be replaced; stainless does not. The mesh has to be sized to keep animals out without choking the draft.
- Multi-flue caps where a stack carries more than one flue.
- Poured concrete crowns with a proper overhang and drip edge, cast to shed water away from the brick rather than into it.
- Crown sealing where the crown is sound but showing early hairline cracks — a flexible waterproof membrane, and a legitimate cheaper option when the crown has not failed yet.
Why we push this one
Fitting a cap and sorting the crown is inexpensive next to relining or rebuilding a stack, and it prevents most of the damage that leads to both. If you do one piece of preventative work on your chimney, do this one. We will tell you if your crown can be sealed rather than replaced — the cheaper fix is often the right one, and we would rather have you as a customer next year.
If water has already been getting in for a while, a chimney inspection will tell you how far it has travelled.
The first five minutes: cold air plugs and stuck dampers
The hardest part of any fire is the start, and two things at the top of the chimney decide whether it catches or smokes. Both leave people thinking the fireplace is broken when it is really a cold-start problem.
The cold air plug
When a chimney has sat unused, the flue fills with a column of dense, cold air — a cold air plug. Cold air is heavier than the warm air of the room, so it sits in the flue like a stopper and refuses to move when you light the kindling. The smoke has nowhere to go but back into the room, and the fire feels like it will not warm up. The cure is to prime the flue first: hold a rolled sheet of lit newspaper up near the damper for a minute to warm the air and break the plug before you light the main fire. A top-sealing damper cap helps enormously here, because it keeps that cold column from forming between fires in the first place.
A damper that is closed or stuck
The other culprit is the damper. A damper left closed is the classic cause of a smoke-filled room, but a partly open or rust-stuck damper is sneakier: it throttles the airflow so the fire can draw, but only weakly, and never builds the heat you expect. Over the years a damper corrodes, warps, or jams halfway, usually because rain has been getting in past a missing cap. If your fire always seems starved for air, have the damper checked — and if it has rusted, a properly fitted cap or crown is what stops it happening again.
Frequently asked questions
Do I really need a chimney cap?
Yes. An uncapped flue takes in rain, snow and animals directly. The three predictable results are a rusted damper, a persistent damp-soot smell in the room, and eventually a nest blocking the flue. A cap is the cheapest part of the chimney and it prevents the most expensive problems.
What is the difference between a chimney cap and a chimney crown?
The crown is the concrete slab covering the top of the brick stack; the cap is the metal lid with mesh sides covering the flue opening itself. The crown protects the masonry, the cap protects the flue. A chimney needs both and they fail in different ways.
How do I know if my chimney crown is cracked?
From the ground you usually cannot. The reliable signals are indirect: a damp patch on the ceiling or wall beside the chimney breast, white efflorescence staining on the exterior brick, or brick faces starting to flake. Any of those means water is getting in, and the crown is the first place we look.
Can a cracked crown be repaired, or does it need replacing?
If the cracks are hairline and the slab is structurally intact, a flexible waterproof crown sealant is a legitimate and much cheaper fix. If the crown is crumbling, has large cracks, or was only ever a thin mortar skim rather than poured concrete, it needs rebuilding. We will tell you which one you have.
Will a chimney cap stop downdraughts and smoke blowing back?
Sometimes. A cap can reduce wind-induced downdraught, and specific anti-downdraught caps exist for exposed chimneys. But smoke blowing back into the room is more often caused by a blocked flue, an undersized flue, or insufficient combustion air in the house — so it is worth diagnosing rather than assuming a cap will cure it.
Will a cap keep birds and squirrels out?
Yes, that is one of its main jobs. The mesh has to be the right gauge — fine enough to exclude animals, open enough not to restrict the draft, and it needs clearing of soot periodically so it does not clog.
My cap is rusty. Does that matter?
It means it is galvanised rather than stainless, and it is on its way out. A rusted cap eventually fails, and the rust staining runs down and marks the brickwork. We replace them with stainless so it does not become a recurring job.
Can you fit a cap on a chimney with multiple flues?
Yes. A multi-flue cap covers the whole stack in one piece, or individual caps can be fitted to each flue. Which is better depends on the stack, and we will look before recommending one.
Book a cap or crown repair in Orland Park
We cover Orland Park, Tinley Park, Palos Heights, Homer Glen, Mokena and the rest of the Southwest Suburbs, seven days a week from 7:00am to 7:00pm. Call (708) 432-3430 or book online and we will call you back to confirm. The price is agreed before any work begins — see pricing.