Glossary of Terms

Ash dump: A small opening in the floor of the firebox into which the ashes can be pushed.

Bonding agent: A liquid mixed into mortar to help it bond (stick) more completely.

Bad brick: Brick that has become soft from age and/or furnace exhaust and that won’t resist the weather or bond well enough to be repaired with new mortar. It needs to be replaced with new brick.

Cement: A compound usually mixed with water and sand that dries very hard.

Chemical flue wash: A substance applied to the flue to remove creosote glaze (we don’t do or recommend doing this).

Chemical wash: A chemical that is applied to your chimney on the outside to clean and remove surface dirt and some kinds of damage, usually due to water/weather/flue leakage.

Clean out door: A metal door installed above the smoke shelf so that area can be cleaned out. It also makes it unnecessary to remove wood stove inserts from the firebox for cleanings and inspections.

Course: A horizontal layer of brick.

Corbel: A fancy arrangement of brick, usually at the top of a chimney.

Creosote glaze: The residue left in your flue after creosote flakes have burned.

Crown: A layer of cement at the very top of the chimney that protects the bricks and mortar from the wear and tear of the weather. Every chimney has (or has had) a crown. A good crown usually lasts between 20 and 30 years before wearing away and needing replacement.

Damper: A metal blade inserted in an assembly that opens and closes a flue. It acts as a door to the flue.

Efflorescence: The powdery deposit the results from water evaporating from brick and mortar. It means that water has completely penetrated the chimney and the chimney needs waterproofing.

Firebox: The inside of the fireplace where the wood is burned.

Fire brick: Brick built to withstand the heat of fire inside the firebox.

Fire brick splits: Fire brick that is made 1/2 as thick as regular fire brick. Made for wood stoves and other special installations.

Fireclay: A substance mixed in with mortar to resist heat. It goes in the firebox.

Flashing: Two sections, top (counter, the chimney part) and bottom (step, the roof part) of metal attached to your roof and chimney to prevent water leaks. This must be metal and not just tar, to fully protect against leaks.

Float: A thin layer of mortar applied to seal brick.

Flue: The inside of your chimney that channels the smoke up and out.

Flue tile: A square, rectangle, or round piece of clay or pumice, hollow in the center, that lines the inside of the chimney. It gives a flue longer life than a regular brick flue. It is also a single piece at the top of the chimney.

Hearth: The flat area in front of your fireplace, usually made of brick.

Hearth facing: The vertical area at the fireplace, along the sides and above.

Insert: A wood stove placed into an existing fireplace opening.

Leeching: Water moving through the walls of a chimney and reacting with the chemicals causing a white residue (efflorescence).

Lentil (bar): A cast iron L-shaped bar at the top of the opening of your fireplace that supports the brick over the firebox opening.

Liner: A metal pipe that is put inside the flue to make a separate chamber to take out exhaust fumes. They are used with furnaces and wood stoves, not in normal fireplaces.

Mortar: A combination of cement, lime, sand and usually a bonding agent. It’s put between brick to hold them together.

Parge: A coating of mortar on the inside of the flue for more durability.

Popped joints: Mortar joints that are pushed out by the action of the brick contracting and expanding due to heat fluctuations.

Popping: Bricks that are cracked or have had the brick face break off. This is due to water absorption.

Prep: Short for preparation, to remove or clean or prepare for repair work.

Rain caps: A metal top that goes on the top of your chimney to keep rain, birds, animals, leaves and wind out of your chimney. Also called a flue cap, chimney cap, etc.

Rebuild: To tear down and re-do a structure, using the same or new brick.

Scaffolding: Metal brace and plank structures used for mason and contractors to stand on while doing high work.

Security pipe: Double-wall insulated pipe for outside use with wood-burning appliances.

Seeping: Water moving through brick and mortar.

Shoulder: The part of your exterior chimney that moves out to be large enough for the firebox.

Shoulder caps: Metal or cement plates that cover the shoulders of the firebox to prevent water penetration.

Skim coat: A watery, thin layer of mortar or cement.

Smoke shelf: A flat area behind the damper the helps the chimney draft correctly.

Spalled: Bricks that have broken faces due to water penetration.

Strike: To shape the mortar between the bricks. This is done with a tool called a striker.

Sweep: To clean the flue, smoke shelf and firebox of soot and buildup to make it safe to use your fireplace, wood stove, etc.

Spot-point: To tuck-point just the holes or gaps as needed.

Tear down: To remove loose bricks and mortar, as tuck pointing cannot be done if bricks are loose.

Top-closing damper: A damper assembly that is attached at the top of your chimney.

Tuck-pointing: The act of removing soft or bad mortar and replacing it with good, new mortar. The soft or bad mortar is removed to the point where it is hard again, at least 1/4 of an inch so a good bond can be gotten with the new mortar. This is considered to be normal maintenance for a chimney. The amount of time in between tuck-pointing varies, depending mainly on the weather. If bricks are loose they should not be tuck-pointed, but replaced or re-lain.

Waterproofing: A chemical solution applied to chimneys to help stop water penetration and damage. It is not permanent, but most manufacturers say it will last 10 years.

Feel free to call us with any questions!