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    Fireplace Fireboxes

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    Firebox Buyer's Guide

    What is the difference between a fireplace and a firebox? These terms are often thrown around and used interchangeably. We'll set the record straight so you know exactly what you are looking for.

    Here's an overview of what fireboxes are and why they're important. We'll also cover what they are made from, how they're installed, and how to choose the best one for your home. You can also see our list of the top five brands we recommend.

    Fireplace Fireboxes

    Fireplace vs. Fireplace Box

    A fireplace fire box is the structure that contains the fire and holds your wood or gas fuel. In other words, the firebox is just a box. It doesn't include the fuel source like a gas log set or burner.

    All fireplaces (including gas, wood-burning, and pellet stoves) contain a fire box. With open wood-burning fireplaces, the firebox is pretty much all there is. The chimney is separate from the fireplace box, but it is the fireplace box that holds the wood and contains the fire. In this case, "firebox" and "fireplace" are essentially the same thing. There aren't other components like a gas burner or gas log set, so the firebox is all there is besides the venting.

    Fireplace Fireboxes

    Gas fireplaces are a bit more complicated. A gas fireplace includes a "firebox" by design (the area that houses the fire) and a gas log set or fire glass set and burner to create the flame effect. In the case of a gas fireplace, referencing the fire box is just speaking to the area where combustion will occur. Referring to the fireplace itself is talking about the entire unit, including the firebox, gas burner, and log or glass set.

    Keeping It All Straight

    It's important to know the correct terms when buying a gas fireplace or firebox online. Here are some tips to help you make the right purchase.


    • Lower cost. A basic vent free gas fire box costs less than a fireplace. Some models are only a few hundred dollars.
    • No BTU ratings. The manufacturer might list the BTU rating for the log set you can buy separately, but the unit itself will have no specific ratings since there is no burner included.
    • No mention of control options, remotes, or description of the log or glass set.
    • Usually mentions the recommended gas log or glass set size.
    • Remember, the firebox is only a box. All of the other features of a gas fireplace such as the logs and burner are not included.


    • More expensive. Especially with gas appliances, the gas fireplace will often cost more than just the fire box.
    • Lists BTU ratings and/or gas pressure requirements.
    • Includes information about how the unit is controlled
    • Describes the log or glass set included with the unit.
    Fireplace Fireboxes

    Again, the term firebox refers to the box or opening that contains the fire. A wood-burning fireplace is only composed of a firebox and chimney components. So in the case of wood burning, firebox and fireplace are essentially the same things.

    If you buy a gas firebox, however, you will need to purchase the gas burner and log set separately.

    Fireplace Fireboxes

    Materials and Function

    Fireboxes are either metal, metal covered with masonry, or just masonry. Prefabricated fireboxes often consist of a metal insert that may be lined with stone, brick or a decorative liner.

    The purpose of a firebox is to provide protection. It keeps smoke and hot gases from seeping into the walls and igniting wood beams within the walls. The firebox also keeps any water from leaking into the walls or floor.

    When to replace a firebox

    A cracked or damaged fire box is a fire hazard and could also allow water to damage your home. If you notice crumbling mortar or suspect that the firebox could be damaged, have it inspected or arrange to replace it right away. Visible cracks in the firebox also signal that it's time for a replacement. While some cracks can be patched and repaired, the long-term solution is a replacement.

    Fireplace Fireboxes

    Wood-Burning Fireplace Fireboxes

    These units burn wood and can be converted to burn vented gas or vent-free gas logs. Make sure the correct venting system is in place and that you have the proper clearances (distance away from flammable material).

    The Superior WCT3000 Louvered Wood Burning Fireplace is a great example of these types of models.

    Open wood-burning fireboxes are ideal if you don't want to have a masonry fireplace built on site. If converting to gas, it's possible to use vent-free gas logs, but keep in mind that the chimney will lower the heating efficiency. If efficient heat is a high priority, opt for a gas fireplace box model specifically designed for vent-free use.

    Fireplace Fireboxes

    Note that this section only deals with open wood-burning fireboxes. Any high-efficiency wood-burning fireplace models with a closed front will not use the term "firebox" in this way.


    • Versatility. You can switch between wood-burning, vented gas or vent-free applications.
    • Large, beautiful flames. Open wood-burning and vented gas appliances typically have better flames than vent-free models.
    • Great for warmer climates or infrequent use. These models aren't as heat efficient.
    • Less expensive than a site-built masonry fireplace.
    • Virtually no installation restrictions. Just make sure you have the proper venting and clearances and you're good to go.


    • Less efficient. Even with a vent-free gas log set, some of the heat is lost to the chimney.
    • Burns more fuel. Not only is heat lost, but the lower efficiency uses more fuel.
    • Venting components make it more expensive to operate than vent-free gas fireboxes.
    • Often requires professional installation, resulting in more labor costs.

    Gas Fireboxes

    The term "firebox" is most common when referring to gas appliances. It houses the vent-free gas logs or glass set, but these are sold separately. The fireboxes come as a metal enclosure with a flat floor and will occasionally have a decorative liner or blower. The Monessen 36 Inch Lo-Rider Clean Face Vent Free Gas Firebox is one example and here's another vent-free model. Note that they will not come with a burner, as these are also sold separately.

    These metal fireboxes are made to be framed into a wall and are for vent-free applications only. Because direct vent fireplaces and b-vent fireplaces are designed for use with a specific vent system and diameter, they will always be supplied with their own burner system.


    • Relatively low cost.
    • Allows for customization since the gas log sets are purchased separately.
    • No need for venting equipment.
    • More heat efficient and ideal for colder climates.
    • Easier to install than open wood-burning fireboxes.


    • Cannot be converted to vented gas or wood-burning.
    • Vent-free appliances can release low levels of particulates into the room air. They are not suitable for people with severe air-quality sensitivities like asthma or bronchitis.
    • May require the installation of a gas line.
    • Most are limited to a traditional square fireplace shape.
    • Not recommended for small rooms.
    • Banned in certain states and cities worldwide.
    • Not for use at high elevations.

    For more information about vent-free installation restrictions, please read the vent-free section in our gas fireplace article.

    Fireplace Fireboxes

    Industry's Finest

    There are a number of different gas firebox manufacturers available, with different design and sizing options to fit your exact needs.

    Empire — In business since 1932, this manufacturer specializes in gas hearth appliances. Their very popular gas firebox lineup, known as the Breckenridge series, offers three tiers of sub-models. Each model offers unique liner and blower options, with progressively larger viewing areas with each tier.

    Monessen — Having long focused on vent free gas models, Monessen offers an impressive lineup of both traditional and floor level vent free fireboxes. Competitive pricing and solid build quality ensure strong value from this manufacturer.

    Stone Age Manufacturing — This respected manufacturer of indoor and outdoor masonry fireplaces offers a unique option for customers wanting the look of a real brick fireplace. Consisting of individual sections that are assembled and finished with firebrick, their fireboxes offer a very long-lasting and realistic option for customers that want to use a vent free log set but maintain the look of a masonry fireplace.

    Superior — Part of the IHP lineup of products, this manufacturer offers a broad range of wood burning open fireboxes that can be installed to burn wood or be converted to vented or vent free gas applications. The firebox itself is part of a larger system, using an air-cooled chimney system to vent.

    Firebox Installation

    When buying a replacement firebox or shopping for a gas log set, start by measuring the dimensions of the current firebox. You will need to measure the front width, back width, height, and depth of the firebox.

    Fireplace Fireboxes

    Installing a Wood-burning or Vented Firebox

    These fireboxes should be installed by a professional or a skilled handyman.

    • Start by reading the owner's manual carefully.
    • Plan the vent route and contact eFireplacestore NFI certified technicians to get appropriate venting components.
    • After your firebox arrives, frame the opening according to the manufacturer's instructions.
    • Slide the unit back into the framed opening until mounting flanges touch the adjacent framing.
    • Make sure the firebox is still far enough away from flammable material. The instructions will give specific distances to measure.
    • Secure the firebox by nailing through the flanges.
    • Add your custom surround veneer (i.e. brick, stone, or tile).
    • Construct all venting components (For detailed information, consult our article on how to choose the correct venting here .)
    Fireplace Fireboxes

    Installing a Vent-Free Firebox

    • Check with local authorities to see if vent-free appliances are approved for use in your area.
    • Consult with NFI certified professionals and located a certified plumber to install or hook up any necessary gas line connections.
    • Once gas lines are installed, construct framing dimensions according to the manufacturer's instructions.
    • Make sure the firebox still has the correct clearances (appropriate distance from flammable material).
    • Secure the firebox through the nailing flanges.
    • Add your custom veneer surround to complete the look.

    For more detailed information on installation, check out this article.

    Care and Maintenance

    The proper care and maintenance will keep your firebox safe and functioning for years to come. Feel free to read this article for even more tips on fireplace care and maintenance.

    Fireplace Fireboxes

    Wood-Burning Firebox

    • To clean, remove the fire log grate and sweep out the ashes. You can dispose of the ash or read about alternative uses for wood ash. Clean the bottom of the firebox with warm soap and water. Use creosote remover and a wire brush to remove creosote buildup around the firebox.
    • Check the firebrick for cracks and inspect the chimney for blockages. Schedule a professional chimney sweep each year. (If using a vented gas appliance, you should schedule a gas vent inspection each year.)

    Gas Firebox

    • Read the owner's manual to find out the recommended cleaners. Before cleaning, unplug the gas line to the unit and remove the gas logs or other decorative media. If possible, take the logs outside and scrub them with a soft brush. You can vacuum the dust and other debris out of the firebox. When you're finished cleaning, carefully replace everything and conduct a test run to make sure everything (including the venting) works properly.
    • Vent-free appliances do not require yearly professional maintenance. If you have a vented gas appliance, schedule a yearly gas vent inspection.


    Wood-burning fireboxes are heavy and weigh up to 500 pounds. Gas fireboxes typically weigh no more than 150 pounds.

    Both wood-burning and gas fireboxes usually ship via LTL freight. The freight company will schedule a delivery time that works with your schedule. They often require two or more people to accept the delivery.

    Do NOT sign off on the delivery until you have inspected all of the components and made sure that nothing is damaged or missing. If you sign off, the freight company is no longer responsible for any damage that might have occurred during the shipment.

    Notify the manufacturer immediately if you notice any damaged or defective parts so that you can take advantage of any warranties.

    Fireplace Fireboxes


    Fireboxes provide a way to buy exactly what you need to customize your fireplace. The wood-burning fireboxes save the extra expense of building a masonry fireplace on-site. The gas fireboxes allow you to purchase or replace the firebox without buying the gas burner or log sets. This is ideal if you already have the gas burner or want more gas log options.

    The key is to remember that the firebox is just a box. It won't come with the necessary venting for a wood-burning fireplace or with the gas burner and log set for a gas fireplace.

    Have any questions about fireboxes? Contact our NFI Certified Specialists and we will be happy to help!

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    Fireplace Fireboxes Q&A with the NFI Certified Specialists

    * Please Note: All customer questions are answered by our NFI Certified Specialists free of charge!
    11 Questions & 11 Answers
    from Chattanooga, TN asked:
    March 14, 2023
    Do you sell a gas starter for your wood-burning fireboxes?
    1 Answer
    Yes, we do. Here is a link to some of the different log lighter kits that we carry.
    Submitted by: Cody S. on March 14, 2023

    Mike R
    from Atlanta, GA asked:
    February 9, 2022
    Does it have to be an exterior firebox for a screen porch in Atlanta?
    1 Answer
    Due to the humidity and temperature fluctuations that happen, it is recommended to use a firebox rated for outdoor use.
    Submitted by: Aaron D. on February 10, 2022

    from Akron, OH asked:
    May 29, 2021
    Do you have a firebox approx. 18W x 17H?
    1 Answer
    Unfortunately, we do not offer a firebox of that size.
    Submitted by: Aaron D. on June 1, 2021

    Pam O
    from Louisiana asked:
    February 20, 2021
    Do the gas logs and firebox have to be from the same manufacturer?
    1 Answer
    No, a vent-free firebox can house any appropriately-sized ventless gas log set.
    Submitted by: Tyler M. - NFI Master Hearth Professional on February 22, 2021

    from Lamar, AR asked:
    January 5, 2021
    What is the temperature rating on the Empire Breckinridge 36 vent free  fireplace box?
    1 Answer
    The manufacturer does not provide a temperature rating. This firebox is designed to house any properly-sized ventless gas log set.
    Submitted by: Tyler M. - NFI Master Hearth Professional on January 5, 2021

    from Brownsboro, TX asked:
    October 24, 2020
    What is the side lever for?
    1 Answer
    The side lever is usually for fresh air intake during combustion.
    Submitted by: Brennan W. on October 26, 2020

    from Louisiana asked:
    September 9, 2020
    Is it possible to install the firebox of a ventless fireplace on the exterior of a house to save interior room?
    1 Answer
    Yes. Exterior chase installations are quite common and for this very reason.
    Submitted by: Will M. on September 9, 2020

    from Gladewater, TX asked:
    May 15, 2020
    When my firebox is not in use, do I need to close the dampener or leave it open for condensation?
    1 Answer
    When not in use, there would be no need to leave it open.
    Submitted by: Owen O. on May 15, 2020

    from McDonough, GA asked:
    February 15, 2020
    What is the benefit of having an insulated firebox vs. uninsulated?
    1 Answer
    Insulated fireplaces are generally recommended for exterior chase applications where a 3-sided structure is constructed outside the preheated living space to house the fireplace and chimney where the front face of the fireplace is flush with the interior wall. In these cases, the internal firebox can remain closer to outside temperatures which can result in issues with the startup as well as cold hearth syndrome.
    Submitted by: Will M. on February 17, 2020

    from Eugene, OR asked:
    October 5, 2019
    Can I install a firebox in a manufactured home in Oregon?
    1 Answer
    We carry units that are designed for mobile homes but you will want to check with your local building inspector and/or insurance company prior to making the purchase.
    Submitted by: Kathy O. on October 7, 2019

    Katharina E
    from Nokesville, VA asked:
    January 4, 2018
    Hello, I have currently a 2000 built gas fire place, but would like to insert a wood burning insert. With your firebox system, can that be safely done without much alteration to the existing chimney?
    1 Answer
    Inserts are traditionally intended for masonry fireplaces not prefabs. You would have to check if your model is rated for use with an insert otherwise it will not be up to code to do so. There can also be an issue with finding an insert to fit in a prefab and still allow for venting hookup.
    Submitted by: Kelsey C. on January 4, 2018

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