Build a circular masonry fire pit for not much more than the cost of a flimsy store-bought fire ring. With tips from a veteran bricklayer, we’ll show you how.
Doug Montzka, of Montkza Concrete & Masonry in St. Paul, MN, has been in the concrete and masonry business for 23 years. “I started getting requests for brick fire pits a few years ago. It isn’t rocket science, but there are a few tricks to doing the job right.”
Backyard fire pits are still all the rage, and for good reason. There’s nothing like a crackling fire to draw friends and family together. Sure, you could set some stones around a hole or spend a hundred bucks on a steel fire ring. But if you spend twice that, you can build a handsome brick fire pit to create a gathering space in your backyard. We spent $250 on this fire pit. It’s maintenance free and easy to clean out, and it will last forever.
If you’ve ever wanted to learn to lay brick, a backyard fire pit is an excellent project to start with. Even if your brickwork isn’t perfect, the fire pit will still look great. We asked Doug Montzka, of Montkza Concrete & Masonry in St. Paul, MN, to show us some tricks and tools of the trade. Set aside several days to complete your fire pit: First you’ll pour the footing and let it set up. Then you’ll mortar the bricks into place.
Set the larger form in position and spray paint around it. Dig a hole about 8 in. deep and 3 in. larger in diameter than the form.
Check the bottom of the hole with a level. Remove high spots by scraping off soil rather than digging. That way, you won't loosen the underlying soil. Compact the soil with a hand tamper or a 4x4 post.
Before digging, call your utility companies (dial 811; for more info, go to call811.com) to check the location of buried utility lines. Also check the fire pit code in your area. Most require a fire pit to be 25 ft. away from any structures and overhanging trees. Think about how the prevailing winds blow through your backyard. Don’t locate your pit upwind of your patio or where the smoke will blow into your windows or those of your neighbors.
A 3-ft.-diameter fire pit creates enough room for a good fire, yet keeps everyone close enough to chat (and complies with most codes). To make measuring the pit and pouring the concrete footing easy, we used two cardboard concrete form tubes (purchased from a concrete supply company). You could also make your own forms by screwing together 1/8-in. hardboard. Rip a 4 x 8-ft. sheet into four 8-in.-wide strips. Carefully bend and screw two strips together to create a 36-in.-diameter circle, and use the other two to make a 48-in.-diameter circle.
Mark the outside edge of the pit (Photo 1). Then shovel out the soil to a depth of 8 in. (Photo 2). Don’t disturb the underlying soil.
If the forms aren't quite level, raise one end and drive a screw through the stake. If the forms aren't completely round, reposition the stakes.
Bend rebar into half circles and tie them together with wire to make a ring. Fill the forms halfway. Press the ring into the concrete, making sure it doesn't touch the sides of the forms.
Shovel in the remaining concrete until the forms are filled. Recheck level, hammering the forms down if necessary, and smooth the top of the footer. Let the concrete set overnight.
The concrete footing will create a stable base for the pit walls and keep the sides of your pit from cracking as the ground moves over time. Stake the forms (Photo 3) and mix up ten 80-lb. bags of concrete mix (sold at home centers) according to the manufacturer’s directions. If you’re using hardboard forms, stake them so they’re nice and round. Fill the forms halfway and press a rebar ring into the concrete for strength (Photo 4). Finish filling the forms to the top and tap the tubes gently with a sledgehammer until the concrete mix is level. Smooth the top of the footing (Photo 5). Let the concrete completely set up overnight and then remove the forms.
Adjust the spacing between bricks so you won't have to cut the last brick to fit (cutting firebrick isn't easy). Mark the position of every brick on the footing.
Because regular clay brick can crack at high temperatures, we’re using firebrick (also called “refractory” brick) to line the inside of the pit walls. Firebrick is a dense brick that’s kilned to withstand high temperatures. It’s larger, thicker and wider than regular brick, and you can find it at most brickyards. Firebrick is more expensive, but it will stand up to nightly fires for years to come. You’ll need 25 firebricks for a 3-ft. diameter pit.
Because firebrick is so dense, it’s tougher to split than regular brick. “Soldiering” the brick (standing it on end) minimizes the amount of splitting and lets you easily accommodate the curve of the pit. You’ll only need to split four firebricks (use the technique shown in Photo 9), which you’ll place across from one another around the pit to create draw holes for oxygen for your fire. After you split your firebricks, dry-set them in place on top of the footing (Photo 6).
Butter a thin layer of cement on the footer and position your first brick. Butter the second brick and butt it against the first. Continue around the circle checking level side-to-side and back-to-front as you go.
Leave gaps in the firebrick in four spots and then fill them with half bricks. These gaps are "draw holes" that feed air to the fire. Prop up the half bricks until the mortar sets.
Firebrick is mortared with refractory cement, which, unlike regular masonry mortar, can withstand high heat. Refractory cement comes premixed in a bucket and has the consistency of peanut butter.
A margin trowel makes it easier to scoop cement out of the bucket and butter the bricks. A tuck pointer is useful for cleaning up the joints.
Work with four bricks at a time. The secret is to trowel the cement on thin, like you’re spreading peanut butter on toast, and use the tightest joints you can (Photo 7). Continue mortaring the firebrick around the pit, placing the half bricks for the draw holes at four opposite points around the ring (Photo 8). Check for level across the pit and the vertical level of the bricks as you go.
Cup the brick in your hand, keeping your fingers below the top edge of the brick. (Our mason doesn't use gloves, but we suggest you do!) Give the brick a solid tap (a very solid tap for firebrick) on the outside edge near the center hole. Avoid hitting your hand. Repeat 79 times.
Lay a thick bed of mortar and let it harden for 15 minutes. Then lay 3/8 in. of fresh mortar and begin setting brick. Butter one side of each brick before you set it in place.
Working on one-third of the pit at a time, check the level of each course and tap down the bricks as necessary. Stagger the joints between courses for strength.
After you finish each section of face brick, use a jointer to smooth ("strike" or "tool") the joints before the mortar dries too much. The mortar is ready to strike if you press your finger into it and the indentation remains. Striking gives the wall a uniform, polished look.
We used SW (“severe weathering”) face brick (also called “common” or “building” brick) to line the outside pit walls. If your climate doesn’t include freeze/thaw cycles, you can use MW (“moderate weathering”) building brick. Home centers and brickyards carry a large variety of brick. You’ll need 80 face bricks for a 3-ft.-diameter pit. Face brick with holes (“cored”) is easy to split with a brick hammer (Photo 9). It’s easier to form the curve of the pit walls with half bricks. You’ll lay three courses of face brick and mortar them together with Type N mortar mix (sold in 80-lb. bag at home centers, and you’ll need about five bags).
Because face brick is smaller than firebrick, you’ll need to make up the size difference as you lay your three courses of face brick. The difference between the height of your firebrick and the total height of three stacked face bricks will determine the width of your mortar beds between courses. Dry-set the face brick, marking where each course of face brick has to hit the firebrick to make the third course of face brick level with the firebrick.
To keep your mortar joints between courses a reasonable width, first lay a 2- to 3-in.-thick bed of mortar right on top of the footing. Let it set up slightly (15 minutes) and smooth out the top. Then, working on one-third of the pit at a time, mortar each course of face brick into place, leaving a 1/4-in. gap between the firebrick and the face brick (Photo 10). Level the brick between courses, tapping the bricks down when necessary (Photo 11). Remember to leave the draft holes open as you mortar each section of face brick and smooth out the finished joints (Photo 12).
Lay a 3/8-in. bed of mortar across 10 to 12 bricks at a time. Lay the bricks on edge and butter the face of each brick on the outside edge as you go.
Add a small amount of mortar to the joints to fill any gaps. Check level frequently and tap gently with a brick hammer to adjust the spacing. Leave a 1-in. overhang on the outside to allow for rain to drip off. Once all the bricks have been mortared in place, strike the joints for a smooth, finished look.
Finish the pit with a matching “row-lock” cap using regular face brick set on edge. You’ll need about 40 face bricks for this cap, which will help protect the wall joints from rain, keep sparks contained and give you a nice ledge to warm your feet on. We used brick, but you could use natural stone for a different look. Work with 10 to 12 bricks at a time. Lay a 3/8-in. bed of mortar, then butter each brick and press it into place (Photo 13). Work your way around the circle, filling any gaps with mortar and checking level and placement frequently (Photo 14). Smooth the finished joints with a concave jointer.
Give the cement and mortar a week to cure completely before lighting a fire in your pit. Pour a few inches of gravel on the pit’s floor for drainage and you’re ready for your first wienie roast.
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
You'll also need a margin trowel, a mason's trowel, a concave jointer, a concrete float and a brick hammer.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.