Masonry Chimney Defects

Chimneys are typically the largest penetration through the roof and require special attention to seal out rain water and to safely vent fireplaces and gas appliances. Aging masonry chimneys degrade over the years, specifically due to exposure to freeze/thaw cycles. Without proper maintenance, small flaws can lead to big issues within the house.

Deteriorated Mortar

The mortar filling the joints between chimney bricks becomes more and more brittle over the years. As the bond between brick and mortar breaks, gaps become visible allowing an easy entry point for rain water. Repointing is necessary to update the failed mortar and seal out water.

Flashing issues

A properly flashed chimney has head flashing at the high side, apron flashing on the low side, step flashing at the roof to chimney intersection, and counter flashing embedded in the mortar joints to cover the step flashing below. These flashing components are often missing or installed poorly, and then covered with roofing cement or caulking to seal any deficiencies. A properly flashed chimney needs very little sealant applied.

Damaged Crown wash

The chimney crown wash is the cement cap on top of the brick chimney. It seals the area between the brick and chimney liner protrusion, sloping away on all sides to shed water. When the crown wash is damaged, rain can enter the chimney.

Missing Chimney Caps

Chimney caps keep rain from falling down the chimney liner, and those with an integrated spark arrestor prevent large embers from leaving the chimney. Caps also prevent animals from entering the chimney.

Unlined Chimneys

Unlined chimneys can be a serious safety concern. Wood burning fireplaces vent wood smoke, combustion products and extreme heat up and out the chimney. Without a chimney liner, the noxious gasses and smoke are not well contained. A liner should be retrofit into the chimney if the chimney is to be used to vent a fireplace or appliance.

Other COmmon Issues

  • Spalling brick

  • Efflorescence

  • Missing saddles on wide chimneys

  • Leaning chimneys

  • Creosote buildup

  • Antenna strapped to chimney