By Barry Stone
Dear Barry,
Some of the bricks on the interior back wall of my fireplace are loose, and the mortar is crumbly. Since the fireplace is built along the exterior of the building, with no wood construction behind the loose bricks, is this a serious problem? Should it be addressed soon, and if so, what should be done? --Randy
Dear Randy,
Loose bricks in the firebox portion of a fireplace should always be regarded with concern. They can allow heat and combustion byproducts (smoke, creosote, and ash) to vent into cavities within the masonry construct of the fireplace and chimney. Gaps between the outer wall of a chimney and the chimney liner are not always filled with mortar or concrete during the construction process. When heat enters these cavities, it can be transferred to the adjacent wood framing, eventually causing a fire in the attic or at other adjoining structures. Additionally, creosote can accumulate in these unfilled spaces and possibly cause a chimney fire.
These consequences are not likely to occur with all masonry chimneys, but wherever fire safety standards are compromised, it is always best to err on the side of caution. The safest course of action is to have a licensed masonry contractor reset the firebox lining with new firebrick mortar.
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