A chimney splay is the angled or sloped section of masonry found at the base or sides of a chimney where it widens out to meet its supporting structure (often the hearth, breast, or foundation).

Chimney flashing is a thin layer of metal (usually aluminum, copper, or galvanized steel) that is installed where the chimney meets the roof. Its main purpose is to seal the gap between the chimney and the roofing material so that water cannot leak into the home.

A chimney flue lining (often just called a flue liner) is the protective channel inside your chimney that carries smoke, gases, and other byproducts safely from your fireplace, wood stove, or furnace out of the home.

A chimney wall thickness refers to how thick the masonry (brick, block, or stone) walls of a chimney are built. The thickness is important because it affects safety, strength, and heat protection.

A smoke chamber is the part of a fireplace system that sits just above the firebox and below the chimney flue.

A firebox wall is the inner wall of the fireplace firebox—the area where the fire actually burns. It’s built from special heat-resistant materials designed to withstand very high temperatures.

A hearth is the floor area of a fireplace—the part you can see and touch at the base of the firebox. Traditionally made of non-combustible materials like brick, stone, slate, tile, or concrete, it serves both a functional and decorative role.

A fireplace hearth extension is the part of the hearth that extends outward into the room beyond the fireplace opening. It’s there to provide extra protection for your floors and home from sparks, embers, or rolling logs that might escape the firebox.

The hearth slab is the solid, non-combustible base (often reinforced concrete) that sits under the visible hearth and supports the weight of the fireplace and chimney above it. Its thickness is important for both safety and structural stability.