Parts of a Chimney – 13 Parts Labeled, Cap to Clean-Out Door

All 13 parts on the diagram

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Start here: 8 main parts 8

Chimney cap (spark arrestor) A metal hood over the flue. It keeps out rain, debris and animals. Its mesh sides, the spark arrestor, stop embers escaping.
Crown A sloped slab over the top of the brick. It sheds rain away from the masonry and the flue.
Flue liner Protects the brick from heat and acid. Clay, metal or concrete lining the flue, the passage the smoke rises through.
Flashing Sheet metal sealing the joint between roof and chimney against rain.
Brick and mortar The masonry the chimney is built of; also block or stone.
Smoke chamber The funnel above the damper. It gathers smoke and leads it into the flue.
Damper A hinged plate that closes the throat. It is closed when the fireplace is idle.
Firebox The firebrick box where the fire burns.

Outside and on the roof: 5 1

Cricket A small ridge on the up-slope side. It sends water round the chimney.

Inside: 8 4

Smoke shelf The flat ledge behind the damper that helps turn back downdrafts. It is at the bottom of the smoke chamber.
Lintel An iron angle holding up the brick over the fireplace opening.
Ash dump A trap door in the firebox floor. It drops ashes into the ash pit below.
Clean-out door A door into the ash pit for emptying the ashes. Usually in the basement.

How this list was compiled: Read 2026-09-26. (1) Full Service Chimney, Chimney and fireplace anatomy, https://fullservicechimney.com/chimney-fireplace-anatomy/ : chimney cap and spark arrestor, chimney crown, brick and mortar, flue liner and flue tiles, flashing, cricket, mantel, smoke chamber, smoke shelf, damper, lintel, firebox, grate, hearth extension, ash dump, ash clean-out door, footings. (2) Aelite Chimney, The anatomy of a masonry chimney, https://aelitechimney.com/the-anatomy-of-a-masonry-chimney/ : mortar crown, smoke chamber above the firebox and below the flue, smoke shelf behind the damper, damper, lintel of angle iron over the fireplace, ash dump below the firebox, clean-out door in the basement. (3) Wikipedia, Chimney, https://en.wikipedia.org/wiki/Chimney : caps and spark arrestors, flashing and the cricket on a pitched roof, flue liners of clay, concrete or metal, the damper, the firebox. Licence: own work

The drawing: Drawn for this site by script, 2026-09-26. Own work, nothing traced. Licence: own work

How it works

These are the parts of a chimney on a brick chimney and fireplace cut through from top to basement. The exterior parts come first, then what is inside. Start with the 8 main parts.

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On the roof

The cap keeps rain and animals out, and its mesh, the spark arrestor, holds back embers. The crown is the sloped slab over the brick. Flashing seals the joint with the roof, and a cricket sends water round the uphill side.

Inside

The fire burns in the firebox under the lintel. Smoke rises past the open damper into the smoke chamber, a funnel over the smoke shelf, and up the flue, lined with tile. Ashes drop through the ash dump to a pit with a clean-out door.

The flue is the passage; the flue liner is the tile or metal lining it. The damper is often wrongly called the flue.

Questions and answers

What is the top of a chimney called?

The brick is topped by the crown, a sloped slab that sheds rain. Over the flue sits the chimney cap, a metal hood whose mesh sides act as a spark arrestor.

What is the difference between a chimney cap and a crown?

The crown is a slab of mortar or concrete covering the top of the brick. The cap is a metal hood over the flue opening that stops rain, debris and animals getting in.

What does a chimney damper do?

It is a hinged plate at the top of the firebox. Open, it lets smoke up the chimney; closed, it stops warm air escaping when the fireplace is not in use.