Fireplace Safety

Southern California has such awesome weather that we don’t think about our fireplaces very often. Not until the weather changes from sunny and 70 degrees to a chilly 60 degrees. What’s better than a nice fire in the fireplace on those cold evenings?

Since fireplaces are such an after thought for most of us, we thought it was important to remind everyone about some of the dangers associated with a neglected fireplace. Many people in Southern California never have their chimneys swept. As home inspectors, we often see neglected fireplaces, and too often we see chimneys that are in very poor condition. Over time, fires leave deposits in the chimney that contain oils and other debris which can actually catch on fire causing significant property damage.

Types of fireplaces

We generally see three (actually four) types of fireplaces in Southern California. Masonry, pre-cast concrete and factory built fireplaces.

Unlined Masonry – Older masonry fireplaces are made of bricks. Prior to the 1950’s, these brick fireplaces were unlined. That means the interior of the

Unlined Chimney - Click to enlarge

Unlined Chimney – Click to enlarge

chimney is made of the same bricks as the exterior of the chimney, with the bricks exposed directly to the smoke generated by the fire. These chimneys are considered unsafe to use. The rough interior of the chimney can capture and hold a lot more creosote which is flammable. In addition, cracks in the mortar can allow Carbon Monoxide to enter the living space. If you have an older home with this type of chimney, consider having it lined by a licensed chimney sweep. You should not use the fireplace until it is modified.

Lined Chimney - Click to enlarge

Lined Chimney – Click to enlarge

Lined Masonry – After the 1940’s fireplaces were built with oval, rectangular or round clay “tiles”. This gave the interior of the chimney a smooth surface with far fewer mortar joints. This prevents some of the build up and most of the gaps that made older unlined chimneys unsafe. Clay is also less subject to the corrosive action of the creosote. Lined chimneys do still require cleaning.

One common problem with all masonry fireplaces is their seismic instability. During even minor earthquakes, masonry chimneys can easily topple over. During a big earthquake like the Northridge earthquake, thousands of chimneys collapsed. This damaged houses, caused injuries, and obviously rendered the fireplaces unusable. For this and several other reasons, the building codes changed to require non-masonry fireplaces.

Pre-Cast Concrete – Often referred to as Rampart fireplaces, these units were cast offsite and were thought to be a great way to install fireplaces in the large

Cracked Pre-cast Chimney - Click to enlarge

Cracked Pre-cast Chimney – Click to enlarge

developments that were being built at the time. The pre-cast fireplaces, including the firebox and chimney, were trucked to a construction site and lifted into place with a crane. The efficiency of this installation sped construction and reduced the cost to develop houses. The concrete chimneys were cast to look like they were constructed of bricks and can be difficult to identify at first glance. These fireplaces often crack and repair is not recommended. These fireplaces, once cracked, should be removed and replaced.

Factory Built – Modern building standards call for factory built metal fireplaces that have a metal flue surrounded by a wood frame chimney. These are more cost effective than building a masonry fireplace, they are seismically stable, and they are easier to clean. You will see this type of fireplace in most modern houses built since the late 1970’s. These fireplaces do have ceramic or masonry panels inside that are stamped with a brick pattern. This panel shields the firebox from the heat generated by the fire. Over time, these panels do crack and deteriorate. The good news is that these panels are easily replaceable. If your panels have cracks greater than 1/8″, they are not effective at shielding the structure from heat. This is a fire hazard. You’ll need to get them replaced prior to using the panels.

Fireplaces are not maintenance free!

Even though people in Southern California only use their fireplace a few times a year, fireplaces still need to be cleaned periodically. Before you use your fireplace in the fall, be sure to do your own visual assessment. You will need to carefully look inside the fireplace, and up through the flue or chimney. A flashlight is very useful for this. If you see a heavy coat of creosote or soot that is 1/8″ thick or more, have your chimney swept before using it. Also, rust is very dangerous as it can let Carbon Monoxide flow into the living space.

Rusted firebox where top of fireplace meets flue.

Rusted firebox where top of fireplace meets flue.

Tip: Have your fireplace cleaned in the summer. You can usually find a coupon or discounted service in the off season.