Stunning brick fire pit: a masonry masterpiece you can build--with some tips from our veteran bricklayer.
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
Dig the pit
Before digging, call your utility companies (dial 811; for more info, go to call 811. 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 ($45 for the two from a concrete supply company). You could also make your own forms by screwing together l/8-in. hardboard. Rip a 4 x 8-ft. sheet ($7) 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 l). Then shovel out the soil to a depth of 8 in. (Photo 2). Don't disturb the underlying soil.
Pour a sturdy footing
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 ($3.40 per 80-lb. bag 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.
Dry-set the firebrick liner
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 ($2 per brick compared with 75 cents or less), 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).
Mortar the firebrick
Firebrick is mortared with refractory cement, which, unlike regular masonry mortar, can withstand high heat. Refractory cement comes premixed in a bucket ($10 per half gallon at brickyards) 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.
Complete the outside walls with face brick
We used SW ("severe weathering") face brick (also called "common" or "building" brick; 25 cents to 75 cents per) 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 ($5 per 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).
Finish off the top lip
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.
RELATED ARTICLE: MEET A PRO
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."
* 36" cardboard concrete form ($15 at a concrete supply company)
* 48" cardboard concrete form ($30 at a concrete supply company) or use a 4' x 8' sheet of hardboard to make both forms
* Ten 80-lb. bags of concrete mix
* Two 10' lengths of 3/8" rebar (at a concrete supply company)
* 25 firebricks (at a brickyard)
* One half-gallon bucket of refractory cement ($10 at a brickyard)
* 120 face bricks
* Five 80-lb. bags of Type N mortar mix
* Margin trowel
* Tuck pointer
* Mason's trowel
* Concave jointer
* Concrete float
* Brick hammer
* Spray paint (for marking grass)
by Elisa Bernick
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|Publication:||The Family Handyman|
|Date:||May 1, 2011|
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