Wood-burning fireplaces are becoming less and less common due primarily to their lack of efficiency. They are still romanticized by many and a fairly common amenity in older homes. As an inspector, my primary focus, as with many things, is 1-functionality and 2-safety. Functionality is typically pretty simple, as long as the flu and chimney are free of obstruction, the flu lining is intact, the chimney chase (typically masonry) appears to wearing reasonably well, and the firebox is free of significant cracking, generally speaking you should be okay. Obviously I’m skipping over a few things here to get to the area I want to showcase, safety. The most significant hazards typically noted in association with wood-burning fireplaces and chimneys are a cracked flue and or significant creosote build up.

A cracked flue presents an opportunity for carbon monoxide to enter the living space. One of the most common indicators that this may have occurred is creosote build up on the exterior of the chimney below the roofline. Creosote typically presents as a black residue that could easily be mistaken for mold. Replacing the terra-cotta flu typically associated with wood-burning masonry fireplaces is a potentially costly proposition.

Creosote build up occurs naturally from the combustion of wood. This is why it is suggested that wood-burning fireplaces are cleaned annually when used with any regularity, by a professional chimney sweep. Creosote is very flammable and potentially combustible, this can be a significant fire hazard especially when concentrated over an open flame, as with a fireplace.