Is the Height of Your Chimney a Seismic Liability?

When was the last time you took a good look at your chimney? If you’re like most homeowners, it’s probably been a while since you gave it any thought. But a word of warning from a Lafayette chimney cleaner, the height of your chimney can actually become an earthquake liability, especially here in California. Should you reduce the height of your chimney?

Bay Area Chimneys

Chimney height reduction or seismic liability reduction are the same thing. In the Bay Area, we get most of our wet weather coming in from the south. What this ultimately means for homeowners is that south-facing chimneys deteriorate faster than they would if they were built on any other side of the house. Remember, the mortar that holds them together is water soluble. As a Lafayette chimney cleaner, this is one of the most dangerous things we see.

Reasons to Reduce Your Chimney’s Height

Over time, chimneys in our area become unsupported masonry structures that were exposed to the elements for a hundred years. Just think of what you would look like if you stood outside for decades in the rain and the sun!

A good reason to reduce the height of your chimney is to lower the risk of earthquake damage. More than a couple significant fault lines cross through the Bay Area, including the San Andreas Fault and 6 others that pose considerable risk. Just imagine the destruction of your chimney crashing into the yard, or in the direction of your neighbor’s home. Any Lafayette chimney cleaner will tell you what a serious hazard a leaning or broken chimney is.

Note that an unlined chimney is more susceptible to seismic activity, meaning it’s more likely to break during an earthquake. This is a good reason to reduce your chimney’s height and install a gas burning fireplace insert.

When Mortar Turns to Sand

Lafayette chimney cleaner

Here’s an example of a broken chimney that had become a worrisome seismic liability. As you can see in the photo, this is an issue of poor water management around the perimeter foundation of the house. Because mortar is water soluble, chimneys wick up groundwater. So, if there are downspouts dumping water near the base of the chimney, it draws in the water, turning the mortar into sand. Of course, this process doesn’t occur overnight, but given enough time, it creates a dangerous situation that needs to be taken care of.

Bear in mind that the chimney is the heaviest part of any house, so this would be problematic even in states where earthquakes are uncommon. When the soil around the base of the chimney gets wet, that soft soil allows the chimney to sink. This is something most homeowners aren’t aware of, but it’s common knowledge if you’re a Lafayette chimney cleaner. It’s a glacially-slow process, but after enough rainy seasons have passed, it can weaken the entire structure. This creates a chimney that is more vulnerable to seismic activity. In fact, the chimney can be pulled apart from the fireplace fascia.

Talk to a Lafayette Chimney Cleaner

Gas burning fireplace inserts don’t need a lot of height for venting, so you might consider installing one if you choose to reduce the height of your chimney. To schedule an appointment with The Irish Sweep, call us at (510)521-4088, or use this simple contact form by clicking here. Your safety is our number one priority. That’s why our team is taking special precautions during the pandemic. We look forward to hearing from you.