Chimney anatomy

01 · Chimney cap

A chimney cap sits on the top of the chimney and keeps rain, debris, and animals out.

• Rust can cause it to deteriorate.
• Animal nests can clog it.
• Wind damage can dislodge it.

02 · Crown

The crown is the top surface of the chimney, sloped to shed water away from the flue.

• Cracks can lead to water leaks.
• Worn surfaces may allow moisture to seep in.
• Improper installation can cause pooling water.

03 · Flashing

Chimney flashing is a seal between the roof and the chimney that prevents water from entering the home.

• Corrosion can cause leaks.
• Improper installation may lead to gaps.
• Old flashing can become detached.

04 · Brick and mortar

The masonry of the chimney consists of the bricks and mortar that form its structure.

• Cracks in bricks can let water in.
• Damaged mortar can lead to instability.
• Freeze-thaw cycles can cause spalling.

05 · Flue liner

A flue liner protects the chimney walls from heat and corrosive byproducts of combustion.

• Cracks can allow dangerous gases to escape.
• Erosion of the liner reduces its effectiveness.
• Improper sizing can affect draft.

06 · Smoke chamber

The smoke chamber funnels smoke from the firebox into the flue, improving draft.

• Cracks can allow smoke to leak.
• Creosote build-up can restrict flow.
• Improper shape can affect efficiency.

07 · Damper

A damper controls the flow of air and smoke in and out of the chimney.

• Rust can prevent it from sealing properly.
• Warps may cause it to stick.
• Debris can obstruct its movement.

08 · Firebox

The firebox is the chamber where the fire is built and burns.

• Cracks can lead to heat damage.
• Loose bricks reduce efficiency.
• Mortar deterioration can cause gaps.