Can You Use Regular Bricks to Build a Barbecue?

The chimney and fireplace chapter of the International Residential Code has no section for a barbecue, so its masonry fireplace rules are the nearest code reference. In those rules, ordinary solid brick, and block grouted solid, make up the body of the masonry. The firebox gets a lining of firebrick at least 2 inches thick or another approved lining, or thicker walls with no lining. Your city decides what applies to a barbecue.

Table of contents

• What is the difference between regular brick and firebrick?
• Which parts can be ordinary brick or block?
• Where does a masonry firebox need firebrick and refractory mortar?
• What does the code ask for, part by part?
• Does a built-in gas grill change what the island is made of?
• Does a brick barbecue still need clearance from things that burn?
• Which code applies to a barbecue in your yard?
• Frequently asked questions
• Sources

What is the difference between regular brick and firebrick?

When people say "regular brick," they usually mean the building brick or concrete block that walls are made of. The 2021 International Residential Code (IRC) names firebrick as a lining for a masonry firebox, the chamber where the fire burns; its firebox rule, section R1001.5, also accepts another approved lining. Where firebrick is used, that rule calls for firebrick that meets the ASTM standards the code names (C27 or C1261), laid with medium-duty refractory mortar (ASTM C199).

Refractory mortar has other jobs in the code. It is parged on the inside of a smoke chamber, the space above the firebox that funnels smoke into the flue (section R1001.8), and clay flue liners are laid in a water insoluble kind (section R1003.12).

The fireplace sections do not say why the fire face is treated differently. The code's rule for chimney linings hints at what it expects of a material facing hot gases: an alternative lining is accepted when it holds up, without softening or cracking, to flue gases at temperatures up to 1,800°F (section R1003.11.1). That is a test for the inside of a chimney, not a rating printed on any brick.

Which parts can be ordinary brick or block?

The code's chimney and fireplace chapter has no barbecue section, so this answer comes from its masonry fireplace rules. In them, most of the material around a fire is ordinary masonry:

• Firebox walls. They are built of solid masonry units, hollow masonry units grouted solid, stone or concrete (section R1001.5). With a lining of firebrick at least 2 inches thick, or another approved lining, the back and side walls total at least 8 inches of solid masonry, lining included. Everything behind the lining is ordinary building masonry.
• The hearth. Hearths and hearth extensions are concrete or masonry, supported by noncombustible materials and reinforced to carry their own weight and the loads put on them (section R1001.9). A fireplace hearth is at least 4 inches thick (section R1001.9.1).
• Chimney walls. Around a flue lining, the code's summary table calls for solid masonry units, or hollow masonry units grouted solid, at least 4 inches thick nominal (Table R1001.1).

Two details in those rules matter if you are weighing concrete block. Where block with hollow cores forms a firebox or chimney wall, the code calls for the cores to be grouted solid. And the wall thickness the code gives counts all of the masonry, lining and block together.

A BBQ island is a different shape from a fireplace, and the code text above is written for fireplaces. The BBQ islands page shows what an island quote has to settle, and the outdoor fireplaces page covers the fireplace side.

Where does a masonry firebox need firebrick and refractory mortar?

In a masonry fireplace built to the IRC, the surfaces that meet the fire and the smoke get the special materials:

1. The firebox lining. Firebrick at least 2 inches thick, with joints between the firebricks no wider than 1/4 inch, laid in medium-duty refractory mortar, or another approved lining (section R1001.5).
2. The smoke chamber. Its inside surface is parged smooth with refractory mortar. Its walls are at least 8 inches of solid masonry, or 6 inches including the lining where a firebrick lining at least 2 inches thick, or a vitrified clay lining at least 5/8 inch thick, is provided (section R1001.8).
3. The flue. Masonry chimneys are lined, and clay flue liners are laid in medium-duty water insoluble refractory mortar (sections R1003.11 and R1003.12).

The code also allows a firebox with no lining. Then the back and side walls are at least 10 inches of solid masonry (section R1001.5), and the summary table puts the two choices side by side: 10-inch solid brick, or 8 inches where a firebrick lining is used (Table R1001.1). So the fireplace rules do not ban ordinary solid brick next to the fire. It asks for more of it when there is no lining, and it still calls for refractory mortar inside the smoke chamber.

What does the code ask for, part by part?

This table sums up the 2021 IRC's masonry fireplace and chimney rules cited in this post. Measurements are minimums unless the table says otherwise.

These are rules for masonry fireplaces, and the table has no row for a barbecue. Chapter 10 of the IRC has six sections: masonry fireplaces, masonry heaters, masonry chimneys, factory-built fireplaces, factory-built chimneys and exterior air supply. None is written for a barbecue, so read the table as the nearest code reference and ask your city how it treats one.

Does a built-in gas grill change what the island is made of?

A gas grill brings a code rule of its own. A gas grill set into an island is an appliance, and the IRC's fuel gas chapter says that cooking appliances designed for permanent installation, grills and barbecues among them, are listed to national standards and installed in accordance with the manufacturer's instructions (section G2447.1). That makes the grill maker's installation instructions part of the code requirement for the island that holds it, so whatever they say about the enclosure around the grill applies to the island whatever your city decides about the masonry fireplace rules above.

If you are still deciding between a kit, a prefab island and one made on site, the comparison of kit, prefab and custom BBQ islands covers what each kind leaves to you.

Does a brick barbecue still need clearance from things that burn?

Both sources cited here point that way. Even for a masonry fireplace, the code keeps combustible material away from the masonry: wood beams, joists, studs and other combustible material stay at least 2 inches from the front faces and sides and at least 4 inches from the back faces, and that airspace is not filled except for fireblocking (section R1001.11).

The National Fire Protection Association makes the same point about grills. Its grilling safety guidance warns that a grill too close to anything that can burn is a fire hazard. It advises placing the grill well away from the home and deck railings, and out from under eaves and overhanging branches. It also advises keeping children and pets at least three feet from the grilling area.

Which code applies to a barbecue in your yard?

The code that applies is the one your city or town has adopted. The Town of Queen Creek, for example, adopted the 2021 International Residential Code and the 2021 International Fuel Gas Code, among other 2021 codes, effective January 1, 2023, and applications received from April 1, 2023 must be designed to the 2021 edition. The Town also lists its own 2021 amendments, and another city may be on a different edition. Your city's building safety office is the place to ask how it treats a masonry barbecue.

This post describes what the code text says. It is not a build method, and it does not describe how any particular contractor works.

Planning a BBQ island or an outdoor fireplace? Request a quote or call 480-807-5499, and what the quote includes is settled with you at the first contact. Big B's Bbq's and Beehives Inc, ROC 153059, holds a Specialty Dual CR-5 license, restricted by the Registrar to BBQ's and fireplaces, planters and decorative walls.

Frequently asked questions

Can I use concrete block instead of brick for a barbecue?

The chimney and fireplace chapter of the International Residential Code has no section for a barbecue. In its masonry fireplace rules, the nearest reference, firebox walls can be solid masonry units, hollow masonry units grouted solid, stone or concrete, so block with its cores grouted solid can form the walls. The fire face still gets a lining of firebrick or another approved lining, or the wall is made thicker.

How thick should the walls of a brick firebox be?

For a masonry fireplace, section R1001.5 of the 2021 International Residential Code calls for back and side walls of at least 8 inches of solid masonry, including a lining of firebrick at least 2 inches thick or another approved lining. Without a lining, they are at least 10 inches of solid masonry. That chapter has no separate rule for a barbecue firebox.

Do I need refractory mortar, or will regular mortar do?

In the code's masonry fireplace and chimney rules, firebrick is laid with medium-duty refractory mortar, the inside of a smoke chamber is parged smooth with refractory mortar, and clay flue liners are laid in medium-duty water insoluble refractory mortar.

How wide can the joints between firebricks be?

No wider than 1/4 inch, under the firebox wall rule for masonry fireplaces in section R1001.5 of the 2021 International Residential Code.

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About the author

Big B's is based in Queen Creek, Arizona. Big B's Bbq's and Beehives Inc holds Arizona contractor license ROC 153059, a Specialty Dual CR-5 license restricted by the Registrar to BBQ's and fireplaces, planters and decorative walls, and has been licensed by the Arizona Registrar of Contractors since March 2000.