Brown staining and scorched paint appear on the wall directly above a fireplace opening. What does this suggest?

Staining above a fireplace opening is a record of where combustion products have been going. If the flue were drafting properly, smoke and heat would rise into the throat and up the chimney, and the wall above the opening would stay clean. Brown staining and scorched paint mean the opposite has been happening repeatedly — smoke rolling out of the opening and up the face of the wall. The causes are worth knowing because they are all correctable: a closed or restricted damper, a blocked or undersized flue, a firebox opening too large for the flue area, an inadequate smoke shelf, or a house so tight or so depressurised by exhaust fans that the chimney cannot establish draft. Since spillage means combustion products entering living space, the inspector reports it as a safety concern and recommends the fireplace not be used until a chimney professional evaluates it.

Staining and scorching above the opening record smoke and heat exiting into the room rather than rising up the flue. That is spillage, which puts combustion products into the living space and is reported as a safety concern.

Fireplaces depend on draft to carry combustion products up the flue. Spillage results from damper obstruction, flue blockage or undersizing, poor firebox proportions, or house depressurisation, and it introduces smoke and carbon monoxide into occupied space.

Stains Above Mean Smoke Came Out. A clean wall over the opening is the sign of a chimney doing its job.

Check the damper position and look for obvious flue blockage, then consider house depressurisation — a powerful kitchen exhaust fan can defeat an otherwise sound chimney.

• •Reading spillage staining as normal fireplace patina
• •Focusing on the paint rather than why heat reached it
• •Overlooking house depressurisation as a contributing cause