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Hearth & Floor Protection

After coming in during a cold, dark, stormy night, there’s nothing finer than standing directly in front of your fireplace to soak up the inviting warmth for a few minutes. After a short time of standing in front of the fire, you either need to rotate and warm up your other side, or move further away because if you remain stationary, you may get a little TOO HOT!

Radiant heat emitted from your fires can be inviting, but your outer hearth extension plays a vital role in keeping your fire where it belongs...in your fireplace!

Radiant heat emitted from your fires can be inviting, but your outer hearth extension plays a vital role in keeping your fire where it belongs…in your fireplace!

Many of us have had this experience and know that the area directly in front of the fireplace can get very hot in a hurry, and if an object is left in close proximity to the front of the fireplace for too long, it can burn due to intense radiant heat being emitted from the fireplace.

This fireplace's outer hearth extension is made out of the same green marble that the fireplace's decorative facing is made of.

This fireplace’s outer hearth extension is made out of the same green marble that the fireplace’s decorative facing is made of.

For this very reason, building codes require that every open face masonry fireplace have a Hearth Extension (or outer hearth extension) installed on the floor in front of your fireplace. This Hearth Extension is usually constructed of the same non-combustible materials that the rest of your fireplace’s decorative facing is made out of, whether it be brick or stone or marble, etc.

A properly sized outer hearth extension is vital to keeping the flooring from igniting.

A properly-sized outer hearth extension is vital to keeping the flooring from igniting.

Hearth extensions not only give you a nice place to store your fireplace tools, but they also help try to protect your home’s flooring from the fire’s intense radiant heat and the occasional hot ember that may roll out of your fireplace.

These Outer Hearth Extensions not only need to be the proper size (i.e., cover a large enough area to protect your flooring), but they also need to be constructed of the proper materials as well as be properly supported.

Proper Sizing

Flooring such as Carpet, wood, and Linoleum are all susceptible to catching fire if exposed to intense heat. The farther away you get from your fireplace, the less intense the heat becomes.

For this reason, Building Codes have specified how much area must be covered and protected in order for your fireplace to operate as safely as possible.

The size of the hearth extension required is based upon the size of your fireplace… the theory being that larger fireplaces usually equate to larger fires, and therefore require a larger area of protection in front of them.

This diagram shows the minimum size requirements for hearth extensions depending upon the size of the fireplace opening.

This diagram shows the minimum size requirements for hearth extensions depending upon the size of the fireplace opening.

A fireplace that has an opening size 6 square feet or greater requires an outer hearth that extends at least 20 inches in front of the opening and at least 12 inches to either side. For example, a fireplace with an opening 2 feet tall and 3 feet 6 inches wide has an opening larger than 6 square feet and would require a hearth to extend at minimum 20 inches to the front and 12 inches on either side.

A smaller fireplace with an opening less than 6 square feet needs the hearth to extend at least 16 inches to the front and at least 8 inches on either side.

Yes, this triangular hearth extension is modern looking, but is it safe?

Yes, this triangular hearth extension is modern looking, but is it safe?

As chimney sweeps, we sometimes find fireplaces that don’t have these minimum hearth extension sizes. This is often due to the fact that it was not built properly to begin with, or in the course of a remodeling project, the old fireplace hearth extension was removed and replaced with an improperly-constructed one.

Proper Materials

With the house long gone, it's apparent that this fireplace's hearth extension was laid directly onto the home's raised wooden sub floor.  If it had been properly supported, the foundation would have not only been directly beneath the fireplace, but also beneath the hearth extension, too.

With the house long gone, it’s apparent that this fireplace’s hearth extension was laid directly onto the home’s raised wooden sub floor. If it had been properly supported, the foundation would have not only been directly beneath the fireplace, but also beneath the hearth extension, too.

Most especially, if your home was built on a wooden raised sub-floor, you need to pay special attention that your hearth extension is constructed of the proper materials and provides adequate coverage. Otherwise, heat could transfer through your non-combustible material and ignite the wooden sub-floor beneath! A good example would be if someone’s hearth extension were made out of thin ceramic tile (a material that is not a very good insulator, but is a good conductor of heat) laid directly over a wood sub-floor. Because these ceramic tiles readily conduct heat, they could easily allow heat to transfer through the thin tile and onto the wood flooring directly beneath them, thus causing a fire. As such only materials with an adequate insulating value should be used.

Proper Support

This is the perfect example of how a hearth extension should not be supported!  Using combustible wood goes against building code.

This is the perfect example of how a hearth extension should not be supported! Using combustible wood goes against building code.

Non-combustible materials such as brick, block, stone, and cement are usually quite heavy. As such building codes require that outer hearth extensions be properly supported with no wood support members beneath them. In other words, an outer hearth extension shouldn’t just be built lying directly on top of the wooden raised sub-floor. Outer hearths that are built in this manner are called “floating hearths”.
The reason for this is two-fold:

First, the potential danger of heat transfer is a concern. If the radiant heat were to transfer through your hearth extension and reach the combustible wood support beneath, a fire may occur.

Without proper support, the outer hearth may settle and cause a crack to open up between the fireplace's inner hearth and it's outer hearth.

Without proper support, the outer hearth may settle and cause a crack to open up between the fireplace’s inner hearth and it’s outer hearth.

Second, wood flooring and wood supports stand a higher chance of sagging or settling beneath the weight of a heavy outer hearth extension. This movement (no matter how slight) often opens up a crack between the inner and outer hearth extensions, providing an avenue for hot embers or sparks to come in direct contact with the combustible wood supports beneath and start a fire.

Conclusion

If your Masonry fireplace’s hearth extension does not meet these minimum sizing, material or support requirements, we recommend that you DO NOT BURN FIRES until proper repairs have been made to rectify the situation and your fireplace has been brought up to current building codes. The peace of mind knowing the job has been done right is well worth the minor inconvenience of fixing a questionable situation…especially when it comes to fire safety in your home!

AtoZChimneySweep-SacramentoCA-FloatingFireplace

 

 



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