19th Century Brick Chimneys

Structure

• Chimneys in the 19th century were built differently during different parts of the century and in different locations. Most early chimneys were placed at one or both ends of the structure, while some later chimneys moved inside the walls of the home. In multistory homes, chimneys and fireplaces were often built in a "stack," with fireplace on each floor venting into a single tall chimney. This method decreased the risk of structural collapse.

Lining

• Chimney liners of metal or clay are now standard in new construction, but weren't in consistent use in the 19th century. These liners keep flue gases inside the chimney and prevent leaks. They also prevent creosote and other combustion by-products from seeping into the brick and mortar, increasing the risk of a chimney fire. Some 19th century fireplaces do include a clay-tile lining, but this can be damaged if it hasn't been properly maintained. Have existing linings inspected regularly, and install a lining in any old chimney before using it.

Leaning Chimneys

• Chimneys in old buildings sometimes lean out from the home. This can be dangerous if the chimney is not structurally stable. A chimney that was originally straight can develop a lean because of mortar erosion or settling, or because the mortar on one side of the chimney originally dried more quickly than the other. Salt crystallization and condensation in the flue can also increase the risk of a lean. According to the Building Conservation Directory, any chimney that leans more than 1 out of 100 mm could be considered unsafe, though many chimneys can tolerate a lean of up to 35 mm. Some very old chimneys are designed to lean, however. According to the Buckley Rumford Co., some early log homes have leaning chimneys designed to be knocked over in case of fire.

Considerations

• Many 19th century buildings have been converted to apartments or inexpertly remodeled. The owners sometimes demolish the chimney breasts, or fireplaces, without removing the chimney stack above them. This creates more room in the house, but also destabilizes the chimney, increasing the risk of wall collapse. If your home still has chimneys, but no fireplaces, you may need to build new chimney breasts or add support beams under the unsupported stack.