Step-by-Step
Overview
1 of 1Meet 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.”
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.
Keys to a better fire pit
A well-built masonry fire pit is rock solid, safe to use, and will easily last for as long as you own your house.
Dig the pit
1 of 2Photo 1: Mark out the pit
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.
2 of 2Photo 2: Level the pit
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.
Pour a sturdy footing
1 of 3Photo 3: Stake the forms
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.
2 of 3Photo 4: Add the rebar
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.
3 of 3Photo 5: Finish the footing
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.
Dry-set the firebrick liner
1 of 1Photo 6: Dry-set the firebrick
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).
Mortar the firebrick
1 of 2Photo 7: Mortar the firebrick
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.
2 of 2Photo 8: Create air holes
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.
Complete the outside walls with face brick
1 of 4Photo 9: Split 80 bricks in half
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.
2 of 4Photo 10: Set the face brick
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.
3 of 4Photo 11: Work in sections
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.
4 of 4Photo 12: Strike the joints
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).
Finish off the top lip
1 of 2Photo 13: Mortar the brick caps
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.
2 of 2Photo 14: Fill gaps
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.
