​ ​ The Chimney Clinic is home of all chimney inspection and cleaning concerns, along with all chimney repairs and chimney relining.

Depth

11.2.1.3 - The firebox of a concrete or masonry fireplace shall have a minimum depth of 20"

Throat Location

11.2.1.3.1 - The throat shall not be less than 8" above the fireplace opening

11.2.1.3.2 - The throat shall not be less than 4" in depth

Cross sectional area

11.2.1.3.3 - The cross sectional area of the passageway above the fire box, including the throat, damper and smoke chamber, shall not be less than the cross sectional area of the flue.

11.2.1.3.4 - Rumford fireplaces shall be permitted provided the depth of the fireplace is at least 12" and  at least 1/3 the width of the fireplace opening and the throat is at least 12" above the lintel and at least 1/20th the cross sectional of the fireplace opening.

Thickness and lining

11.2.1.4 - Where low-duty fireclay brick, firebox brick, or the equivalent, at least 2" thick laid medium duty refractory mortar or the equivalent or other approved lining is provided, the total thickness of back and sides, including the lining shall not be less than 8"

Firebox 

nfpa fire code 211 quick links