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How to build a fire pit

Adam_W
Super Contributor

Difficulty: Intermediate

Our gardens and outdoor spaces are increasingly becoming both entertaining and chill-out zones. A fire pit can make a great addition to a back yard. A well-designed fire pit provides a brilliant space to come together with friends and family, and can work as a decorative element in the landscape. Here’s an easy fire pit project you can build.

 

This fire-pit uses a small slab as the base, a circular support, or well, of brickwork and a removable rustic fire-bowl. You can modify the techniques used to suit your needs and materials. It’s a project of two parts as you’ll need to lay the slab first before adding the brickwork. We have mixed our concrete from scratch however you can just buy bagged, pre-mixed concrete. Estimate the concrete volume required by multiplying width by length by depth to obtain a cubic volume measurement. The brickwork will be a circular fan pattern will large in-fills of mortar to create an interesting design.

 

Steps

Step 1

The size of your fire-pit well determines the size of the slab. The well-size is the fire-bowl width (less its supporting lip) plus the length of two bricks. We allowed 1.16m - 700mm for the 750mm diameter fire bowl and 460mm for brickwork.

 

Position a peg where the centre of your fire pit will be, loop a stringline over the peg hold a can of set-out paint at ½ the width of the pit (58cm in our case) and then walk in a circle while spraying.

 

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Step 2

Determine the set-out of one slab side, ideally this should be square with anything nearby such as a pathway or deck. Measure, position your straight edge and mark a line to the required length, our sides were 1.2m. Use builder’s square to set a right-angle for the next side, mark and repeat until complete.

 

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Step 3

Measuring from the lowest side (if on a slope) excavate the area to a minimum depth of 100mm. Check the excavated area is roughly level using your level.

 

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Step 4

Measure excavated area to check size, measure and cut formwork timber and created a square a butt-jointed box frame with internal measurement to match your desired slab size. Position frame and check it is square by measuring diagonals - front-left to rear-right and vice versa - these should be equal. Hammer in stakes at centre of each side on the outside of the frame. Check level on all sides and then use screws through formwork to secure to stakes.

 

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Step 5

Measure and cut mesh to size, allow around 30mm in from all sides. Position in excavated area and place chairs underneath at regular spacings. The chairs will be notched with two height options. Select the higher 40mm one, this should leave the mesh around half-way up the formwork height. Use enough chairs to stop the mesh from sagging at any point.

 

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Step 6

In wheelbarrow dry-mix concrete ingredients at a ratio of 1 part cement : 2 parts sand : 3 parts aggregate. Use the bucket to keep ingredient amounts accurate. Blend well and then slowly add water while continuing to mix. Add water a little at a time until you reach a consistency that is just pourable. Pour into the formwork working down with a shovel to remove air-pockets and repeat process until formwork is full.

 

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Step 7

Once full, use straight-edge to bring to level removing any excess concrete. Allow to dry a little and then use a float to finish surface (or a coarse broom for a textured surface). Cover with builders plastic for at least 24-hours and then allow to cure for around a week before commencing stage 2. Formwork can be removed after around 2 to 3 days.

 

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Step 8

Now that the slab is done, it's time to build the fire pit well. Position straight-edge from corner to corner each direction and mark lines to find exact centre of the slab.

 

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Step 9

Position the fire bowl upside down on the slab and measure in from all four sides to position it in exact centre. Draw a line around the lip of the bowl. Remove bowl and dry-position the bottom course of bricks. To support the bowl their inside face should be around 2cm over the marked circle line. Position bowl on bricks to double-check. Remove bowl, mark on slab around the inside and outside edge of bricks before removing bricks.

 

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Step 10

Using bucket to measure ingredients, make up a batch of mortar in wheelbarrow. The ratio is 1 part cement : 4 parts Brickie’s sand. Dry mix first and then add water slowly while blending. You’ll need a very stiff mix that holds shape well. With marked brick lines as your guide lay a bedding course of mortar and then start laying. Lay the first brick aligned with a side edge of the slab to make sure you are on-line from the start. Use a short level as you go to check that each brick is itself level and level relative to those beside it. Use tape measure to check.

 

AHW26371.jpg

 

Step 11

As you progress, gently pack the large wedge-shaped joints with mortar using your trowel to shave and shape the front edges. Layer a mortar bed on top of the first course and then commence laying the second course. Bricks should overlap so gaps alternate, not be stacked straight up. Repeat process for each course, we made ours three courses high.

 

Step 12

Once laying is complete trim excess mortar and pack extra mortar into any gaps. Allow to cure for time recommended on brick cleaning acid bottle. In a clean bucket mix up brick cleaning acid at recommended rates ensuring all safety directions are followed including wearing suitable safety equipment. Gently rub all bricks and mortar, this will clean surplus mortar from brickwork and smooth mortar.

 

AHW26384.jpg

 

Step 13

This last step is optional, but a timber surround can look fantastic. 

 

Cut timber to make box-frame to surround slab butt-jointing together with construction screws.

 

Excavate around slab if required to accommodate frame. Position surround leaving it around 30mm proud of slab. Check level on each side. Secure with stakes if required, these should be hammered in on outside of frame to height where they won’t be visible.

 

Fill in the spaces created around edge with decorative gravel or pebbles. Our frame was a snug fit around the slab but you could make it larger if desired.

 

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Materials

To create a concrete slab measuring 1.2m x 1.2m x 100mm, you will need:

  • 20mm aggregate x 6 bags
  • Washed beach or Sydney sand x 4 bags
  • Cement x 3 bags
  • Mesh panel 1.8 x 1.2 with 100mm aperture, 5mm wire x 1
  • 100mm x 2.4m treated pine fence palings
  •  50mm treated pine screws
  • Mesh or reinforcing bar chairs 25/40mm x 8
  • Short timber stakes x 4
  • Aerosol set-out paint.

 

For the fire pit well, you will need:

  • Cement 20kg bags x 2 (we used off-white)
  • Brickies sand 20kg bags x 6 (we used yellow)
  • Bricks x 60 (we used white ‘chalk’ bricks) 
  • Brick cleaning acid.

 

For the timber surround, you will need:

  • Timber (we used 50 x 200 x 2.4m treated pine sleepers)
  • 100mm exterior bugle-batten or construction screws
  • Decorative gravel (we used medium/20mm washed river pebbles).

Tools

  • Wheelbarrow
  • Mattock
  • Digging spade
  • Shovel
  • Mixing hoe
  • Screed bar or straight-edge
  • Tape measure and spirit levels
  • Large builder’s square
  • Grinder or bolt cutter (to cut mesh if required)
  • Bucket
  • Brickie’s trowel
  • Straight edge
  • Builder’s pencil
  • Brick cleaning sponge (acid resistant)
  • Chemical resistant gloves
  • Safety glasses.

Images

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AHW26343.jpg

AHW26345.jpg

AHW26346.jpg

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AHW26347.jpg

AHW26349.jpg

AHW26350.jpg

AHW26351.jpg

AHW26352.jpg

AHW26354.jpg

AHW26368.jpg

AHW26370.jpg

AHW26371.jpg

AHW26384.jpg

AHW26385.jpg

AHW26387.jpg

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4 Replies
Community Manager Jason
Community Manager

Fantastic project @Adam_W. We're really excited to share this with the Workshop community and know that your work will inspire a lot of people. 

 

Workshop community members, we'd love to hear your feedback on this new format of "how-to" articles complete with step-by-step instructions and lists of tools and materials. 

 

Feel free to send me a private message here on Workshop or email workshop@workshop.com.au if you have any requests for projects to feature or suggestions about how we can improve the format of these special sponsored articles. 

 

Jason

 

Adam_W
Super Contributor

Thanks @Jason , was great working with the team to put this together for everyone.

BIM_Engineer
Valued Contributor

Hey Guys 

I think the new " How To.." format is great

@Jason  You might wish to

1.Give members access to a PDF down Load off the site.

2.Structure the categories 

3.I often get asked for material links, costings & other info which I embed into the PDFs

Cheers

 

ProjectPete
Valued Contributor

Nice one @Adam_W! A great project and and informative guide.

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