Can Snow Damage My Chimney?

Ohio gets a lot of snow, so it’s not surprising that our technicians are occasionally asked if snow can harm a chimney. The simple answer is that snow itself usually won’t harm a chimney, but it could lead to issues that definitely will harm it.

The Chimney Guys of Pataskala, OH, would like to cover a little about how snow and chimneys mix.

Chimneys and snow damage

While it’s unlikely that the weight of snow will compromise a chimney structure, the moisture in melting snow can cause some pretty serious problems.

The bricks and mortar that make up masonry chimneys are designed to withstand extremely cold temperatures. But they’re not designed to be impervious to the effects of moisture.

If snow is allowed to build up around a chimney, it could lead to various types of damage when it melts or re-freezes.

Freeze-thaw cycles and your masonry

Winter temperatures in central Ohio regularly dip below freezing, keeping snow in the form of snow. Then temperatures go up, causing snow to melt. Then they go back down, causing it to freeze.

If moisture from melting snow enters cracks in the chimney masonry, when temperatures drop, the moisture will freeze and expand. The result can be major brick cracking and structural instability.

Snow and chimney caps

The top of every chimney should be outfitted with a chimney cap or a flue cover. These components guard the chimney flue from incoming rain and snow (as well as from debris and small animals).

When there’s no chimney cap – or when the existing cap is severely damaged – snow will fall right into the flue. This can eventually damage the chimney liner, the fireplace damper and the firebox.

Snow coming in through the open top area of a chimney can also get into unseen spaces around the flue and lead to:

• Interior masonry damage
• Rotting in nearby building materials of the home
• A dangerous mold outbreak

Snow and chimney flashing

The flashing that seals the gap between your chimney and roof is there to keep water from moving down into your home. If snow remains packed around the flashing all winter, it can cause big problems when it starts to melt if there’s a problem with the flashing.

Chimney flashing can warp, rust and become unseated. Strong winds can blow sections of it away. It’s best to have the flashing free of snow to prevent leaks and to make it easy for you or your chimney inspector to evaluate its condition throughout the winter months.

Keep your chimney visible and accessible

Any part of a chimney that’s covered by snow can’t be seen well. This means there could be issues going on that you won’t know about until all the snow melts off. And by that time, a much larger problem may have started.

The best practice is to never let snow build up too much or stay too long on your chimney. Another best practice is to schedule annual chimney inspections with a licensed inspector, whether or not you believe damage exists.

Your inspector will spot early signs of problems and be able to resolve them. Basic chimney inspections cover all readily accessible areas and components of a chimney, including those that could be negatively affected by snow:

• Chimney cap
• Chimney crown
• Masonry
• Chimney flashing

Keep your chimney running right

The Chimney Guys provides a full menu of services, from chimney sweeping and inspections to chimney repairs and rebuilding work. Call us today, or reach out with our simple contact form.