Issues Found in Older Chimneys

In this blog entry, the Chicago chimney inspection service team here at Chimney Sweep Near Me will detail the most common issues found in older chimney constructions.

Chimney Masonry

Pre 1950s chimneys were built of masonry or blocks, and are strangely less durable than the brick chimneys of the 1500s and 1600s. Mortar in masonry based chimneys is easily damaged and eroded, which can cause chimneys to lean or collapse. Through a process called tuckpointing, damaged mortar can be replaced, repairing chimney integrity. Tuckpointin also improves the appearance of your chimney, not just its structural integrity and increases its lifespan. Block chimneys also cause issues. Block chimneys are truly meant to be covered with bricks, but aren’t always, and when they aren’t, they can easily crack, leak, or lean. Block chimneys that are built against the side of wooden frame houses are actually illegal due to ther fire risk. These chimneys should be rebuilt.


Chimney Liner

Often, chimneys in older homes aren’t lined. Unlined chimneys should NEVER be used. Chie liners help stop noxious and poisonous gasses from leaking back into your property which can cause a serious health risk. Unlined chimneys also rapidly build up flammable creosote and tar that sticks to bricks. Unlined chimneys have to be brought up to code. Another issue seen with unlined chimneys is the intense amount of condensation they can produce – especially with gas fireplaces. This can cause serious damage to your chimney as snow and ice freeze and thaws – and can even ruin drywall and wallpaper. Unlined chimneys perform poorly, with strong drafts, and might cause your home to stay cold. Insurance even often doesn cover your home if your chimney is unlined!



Pyrolysis is a chemical reaction that causes organic material like the wood homes are built of to depose when exposed to heat over long periods. Since chimneys in older homes were not constructed in a way that keeps them away from combustible material – for example, like when they rest against wooden parts of your home – they can be a pyrolysis risk. Pyrolysis can take a while to occur – meaning that chimneys that have been assessed as safe for decades or centuries can very suddenly become a safety risk. It’s common in older homes to see wooden two-by-fours against chimney bricks – which is a MAJOR safety risk that should never be tolerated.


Chimney Crowns

Older chimneys often don’t have chimney crowns that, as stated on other blog entries on our website, help to prevent rain from getting into your chimney. Chimney crowns take the majority of sun, rain, wind, and snow exposure, protecting your chimney. Older chimneys that do have crowns aren’t necessarily safe either as the crowns are likely cracked if it hasn’t received rcnt and regular maintenance. Crowns on older chimneys should usually be replaced. You can also install a cap on your chimney, usually metallic which can help prevent sparks from leaving your chimney and causing fires.


Water Issues

Bricks easily soak up water, which isn’t such an issue if they face South and soak up the sun which dries them. However, if your bricks are in the shade, and have regular sun exposure, they can easily freeze in the Winter and cause serious damage. We recommend waterproofing masonry if it cannot fully dry after a rainstorm or snow storm. If you decide you want to waterproof your chimney, make sure to use a waterproof solution that still allows the pores of the bricks to remain open and breath.

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