How Cold Weather Affects Your Chimney
While many homeowners light the fireplace to stay warm during the winter, the cold weather can also have a devastating effect on your chimney. It’s not just the frigid temperatures; it’s the rain, sleet, and snow that is common during this time of year that is so destructive to the chimney. It can accelerate masonry damage, make it difficult to light the fireplace, and even cause dangerous backdrafts.
The combination of cold weather and winter precipitation like rain, sleet, and snow can be very destructive to masonry chimneys. Bricks and mortar are naturally porous materials that absorb moisture like a sponge. When the weather gets cold and drops below freezing, the trapped water freezes into ice. As the ice crystals expand, tiny cracks develop in the bricks and mortar joints. The ice crystals melt when the temperature rises, and the freeze-thaw process starts all over again. The masonry continues to deteriorate as the cracks widen with every cycle. It’s a slow process that is hardly noticeable at first, but as it continues to worsen, the bricks will flake, chip, crumble, and even fall from the chimney exposing gaps in the mortar joints.
During the cold winter weather, birds, squirrels, raccoons, and other critters are also looking for a place to stay warm. Climbing up a chimney is no different than a tree, especially when being chased by a predator. Once on top of the chimney, these naturally curious critters will hop into an open flue to rest. They often are unable to escape and get trapped, which restricts the venting of smoke and fumes. High winds can blow leaves, twigs, and other debris into the flue, which can also cause a flue obstruction. Flue obstructions are hazardous because it can cause toxic carbon monoxide gas to back up into your home instead of exiting the chimney like it’s supposed to.
Cold Hearth Syndrome
The cold weather can also affect the chimney’s draft causing a condition known as cold hearth syndrome. It occurs when the chimney is colder than the home’s interior. It can make it difficult to light the fireplace, and it can also cause a dangerous backdraft. When lighting the fireplace in a cold chimney, there isn’t sufficient hot air (high pressure) to lift the smoke and fumes out of the chimney. The chimney will continue to draw in the cold (low pressure) external air to fuel the fire. The lack of hot air causes the denser cold air to fall back down, pushing smoke and exhaust out of the fireplace instead of up and out the chimney. Warming the flue before lighting the fireplace will help reduce the risk of a backdraft. You can warm the flue by burning a piece of cardboard or tightly rolled newspaper and holding it under the flue inside the firebox until you feel the airflow reversing and going up the chimney, indicating it is safe to light the fireplace.
Cold weather can also contribute to heat loss. Leaving the damper open after the fire burns out, for instance, will cause cold air to be drawn into the chimney resulting in significant heat loss. Be sure to close the damper after the flames are extinguished to reduce heat loss. Installing a top-sealing damper can minimize heat loss. You can also increase heating efficiency by installing glass fireplace doors. Glass doors radiate fireplace heat into the living space keeping it warmer for more extended periods. Repairing masonry damage such as spalling bricks, chimney crown cracks, and replacing a damaged chimney cap will also minimize heat loss.
Our certified chimney professionals can prepare your chimney for the cold wintry weather with chimney inspections and cleanings, masonry repair, waterproofing, and more. Contact us to schedule an appointment to protect your chimney today!