Chimney Sweep Glossary

This plain-English glossary is your go-to guide for the 12 most important chimney terms Seattle homeowners need to know. Whether you own a century-old Queen Anne home or a newer Capitol Hill build, understanding these parts and risks helps you keep your masonry safe, warm, and code-ready year-round.

Seattle’s damp winters and older housing stock make chimney care different here than almost anywhere else. If your home was built before 1950, the brickwork, flue liners, and flashing face extra wear. Learn what we inspect on older masonry chimneys and see how pricing works for Seattle homes.

Creosote

Creosote is the black, tarry, or flaky residue that builds up inside chimney flues when wood burns incompletely. It’s highly flammable and the leading cause of chimney fires in older Seattle homes with historic masonry. Regular sweeping removes creosote before it hardens into a dangerous glaze. See our full list of services.

Flue

The flue is the vertical passage inside your chimney that carries smoke and gases from the fireplace up and out of your home. In older Seattle homes, clay tile flues are common, but they can crack with age. A cracked flue should be relined before use; never ignore gaps or missing mortar.

Flue liner

A flue liner is a protective layer—often clay tile, metal, or poured-in-place—inside the flue that shields the masonry from heat and corrosive byproducts. Older Seattle homes may have no liner or a damaged one; modern codes require a liner rated for wood or gas fuel. [[We test and reline flues in Seattle’s historic neighborhoods|/areas/seattle/].

Damper

The damper is a metal plate inside the flue that opens to let smoke out and closes to keep heat and pests in when the fireplace isn’t in use. In older Seattle homes, dampers often stick or warp from moisture. A stuck damper wastes energy and can overheat the flue.

Chimney crown

The chimney crown is the concrete or mortar cap at the very top of your chimney that sheds water away from the flue and masonry. Cracked crowns are common in Seattle’s freeze-thaw climate and let water into the brickwork, causing spalling and leaks. [[A cracked crown should be repaired before winter|/services/].

Chimney cap

A chimney cap is a screened metal cover that sits on top of the flue opening. It keeps rain, leaves, animals, and wind-driven debris out while allowing smoke to escape. Without a cap, Seattle’s wet winters quickly damage older flues and liners.

Firebox

The firebox is the brick-lined chamber where wood burns in a masonry fireplace. Older Seattle fireboxes often have crumbling mortar joints or cracked bricks from decades of heat cycling. [[We tuckpoint damaged fireboxes to restore safety and draft|/services/].

Smoke chamber

The smoke chamber is the sloped area above the firebox that funnels smoke into the flue. In older Seattle homes, this area can be too steep, too shallow, or lined with rough masonry that traps creosote. A smooth, properly sloped chamber improves draft and reduces cleaning frequency.

Draft

Draft is the upward flow of air and smoke from the fireplace through the flue and out of your home. Poor draft in Seattle’s humid climate can cause smoke to spill into the room or creosote to build up faster. [[We diagnose draft issues in older masonry chimneys|/services/] and recommend solutions like relining or crown repairs.

Spalling

Spalling is the flaking or crumbling of brick or mortar caused by trapped moisture freezing and expanding in Seattle’s wet winters. Older brickwork is especially vulnerable. Spalling exposes the inner brick to further decay and can weaken the entire chimney structure.

Tuckpointing

Tuckpointing is the process of removing damaged mortar from brick joints and replacing it with fresh, color-matched mortar to restore strength and water resistance. In Seattle’s historic neighborhoods, tuckpointing is often needed every 20–30 years to preserve older masonry chimneys.

Chimney flashing

Flashing is the thin metal barrier that seals the joint where the chimney meets the roof. Over time, Seattle’s freeze-thaw cycles and seismic shifts can loosen or tear flashing, causing leaks that damage ceilings and rafters. [[We reseal flashing in Seattle’s older homes to prevent water damage|/services/].

Level 1 inspection

A Level 1 inspection is the standard visual check of readily accessible chimney parts—flue, liner, damper, crown, flashing, and firebox—performed from the roof and firebox. It’s required annually for wood-burning fireplaces in Seattle and is included in most routine sweeps. [[Schedule yours before the rainy season|/tips/how-often-service-chimney-seattle-schedule/].

Level 2 inspection

A Level 2 inspection includes everything in Level 1 plus a video scan of the flue interior and inspection of attics, crawl spaces, and chimney base when damage is suspected or after a chimney fire, earthquake, or major renovation. Seattle’s older masonry chimneys often need Level 2 after a storm or if you’re selling your home.

CSIA certification

CSIA certification is the industry gold standard for chimney professionals, earned through rigorous exams on fire codes, masonry, and safety. At Andrew C. Chimney Company, every technician holds CSIA certification, ensuring your older Seattle home gets expert care that meets modern safety standards.

Frequently Asked Questions