The Importance Of The Firebox

Both masonry and prefabricated fireplaces contain what is known as a “firebox,” which is essentially the visible area of your fireplace where your fire is lit and burns openly. If you want a specialty firebox built or want one just like your previous one, you can count on Lords Chimney to take care of you.

Don’t know much about the firebox and its important role in your fireplace and chimney system? Let us explain. Masonry fireplaces, which are made of bricks, blocks, or stone and mortar, have fireboxes that are built on-site and made of firebrick, which is often yellowish in appearance. Meanwhile, prefab fireplaces—which have become much more common and popular over the past 25 years or so—have lightweight metal fireboxes along with metal chimneys. These metal fireboxes are made of cast refractory panels.

Both types of fireboxes can present their own problems. Because masonry fireboxes are built to the specifications of the original mason, their quality varies greatly, and the firebrick therein tends to deteriorate over time because of the direct exposure to extreme heat. Prefab fireplaces, meanwhile, must abide by very specific installation instructions to ensure that proper clearances are met, and it’s important that their fireboxes be professionally inspected for inevitable signs of wear and tear. Because of the amount of water we get here in Houston and the infrequency with which we use our prefab fireplaces, it’s very common to see improperly maintained fireboxes rusting out rather quickly.

Cracked refractory panels on the bottom of the firebox as well as the sides.

Broken Refractory Panels

Masonry Fireplace Firebox Issues

If you see loose firebricks or holes in the mortar or brick in your firebox, don’t put off calling about having your firebox repaired or rebuilt. A firebox in disrepair means that your fire may not stay contained and could wind up posing a huge danger. Your firebox receives the brunt of your fire’s heat and understandably begins to show wear over time. Even though firebrick is designed to stand up to heat, its joints will eventually begin to deteriorate from the expansion and contraction cycles caused by the extreme heat of a fire as well as the changing seasons. Chimney leaks are also notorious for causing damage to the firebox, as rainwater can mix with soot to create an acidic substance that will erode mortar joints. We also often find that the original firebox was built without special high-temperature refractory mortar, making it more vulnerable than a firebox built with refractory mortar.

Prefabricated Fireplace Firebox Issues

Because the prefab’s firebox comes as part of a complete factory-built system, it’s important to have a professional check out your fireplace so you can be assured that all parts are compatible, installed correctly, and still in good working order. It’s common knowledge that factory-built fireplaces cannot withstand the amount of use that their masonry counterparts can. And according to the Chimney Safety Institute of America (CSIA), over half of the prefab units inspected by professionals are improperly installed.

Prefab firebox clearances prove to be especially difficult for homeowners to check themselves. With regards to your firebox, let us reiterate: Call a professional! Your safety isn’t something you want left to chance. Here in Houston, we also find that many prefab fireboxes rust out rather quickly, due to the large amounts of rain we receive and the infrequency with which we use our fireplaces. Schedule an inspection today for the peace of mind you deserve.

Live in the greater Houston area and have concerns about your firebox or need a firebox replaced? Reach Lords Chimney at 281-497-4000, or use our convenient appointment request form!


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