5 Ways Winter Weather Can Damage Your Chimney

Winter is a festive time of year where family and friends often gather around a warm and glowing fireplace to spread holiday cheer. However, it is not always a merry and bright time of year for the chimney. In addition to brutally cold temperatures, the chimney also faces the brunt of wind, rain, and snow that winter weather often brings. The 2019-2020 winter weather season brought record-breaking precipitation. According to The National Oceanic and Atmospheric Administration (NOAA), there was a total of 7.71 inches of winter precipitation, making it one of the most-wettest periods in 125 years. Plus, much of New England was blanketed with above-average snowfall.

Damaged Chimney Cap

Since the top of your chimney rises above the roof, it is most vulnerable to the damaging effects of winter weather. High winds, pounding rain, sleet, and hail, can damage the chimney cap. A gust of wind can blow off a chimney cap already weakened by previous storms. A damaged or missing cap exposes the flue to rain, snow, even downdrafts.

The moisture can soften interior masonry and clay flue liner tiles, and rust metal components like the damper. Also, small animals and debris can obstruct the venting of smoke and fumes, causing dangerous carbon monoxide gas to seep into the living space.

Cracks in the Chimney Crown

The chimney crown is also vulnerable to wintry conditions. When the cement surface cracks, moisture can seep inside the chimney and damage its masonry walls. Also, the freeze-thaw effect can further accelerate the deterioration of the chimney crown. As the surface cracks absorb the moisture and freezes, the expanding ice crystals widen the cracks even more. Warmer weather results in a thawing process where further deterioration and erosion can cause extensive chimney damage.

Spalling Bricks

The freeze-thaw cycle is also damaging to the exterior of masonry chimneys and can cause spalling bricks. Both bricks and mortar are naturally porous materials. When you look closely at the bricks, you may spot tiny holes and crevices in the surface. Moisture collects in these channels where it may go through a series of freeze-thaw cycles every winter. It causes the bricks to spall or crack, leading to further deterioration. The moisture also softens and erodes the mortar leaving gaps in the mortar joints. In severe cases, spalling bricks can destabilize the chimney causing it to lean or even collapse.

Water Leaks

While spalling bricks, cracks in the chimney crown, and a damaged chimney cap enable water intrusion, damaged flashing is another source of a water leak. The flashing is a metal strip that seals the seam between the roof and chimney.   Stormy weather can damage the flashing exposing the seam for water to seep inside the gap.  Water stains on the ceiling or along the walls near the fireplace are often a sign of damaged flashing.

Rusted Damper

Water intrusion can cause metal components like the damper and damper assembly to rust making it a challenge to operate. The damper must be fully operable to vent dangerous fumes during a burning fireplace and to prevent water intrusion when the fireplace is not in use. A damaged damper also contributes to energy loss.

Now that winter is behind us, homeowners should ask their chimney sweep to inspect the chimney for winter weather damage. Making any necessary repairs now will ensure your chimney is ready for the next season.