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How to Build an Outdoor Stone Fire Pit

by Olivia

Thinking of building an outdoor stone fire pit?

Sick of those perfect afternoons being cut short, when you’re gathered with a few friends outside at your home and the sun goes down? We get chilly – some of your friends decide that this signals time to head home, while others retreat indoors. Indoor gatherings mean dropped nibblies, vacuuming, spilled drinks – no thanks! Outdoor gatherings are the way to go for sure and an outdoor fire pit means you can extend those fun afternoons well in to the evening as the temperature drops!

Outdoor fire pits come in a range of sizes and designs, but they also come in a variety of budgets! If you have the time and/or money to spend on your outdoor space, then you can create something truly spectacular. The great news is that building a stone firepit yourself can also be done for very little cost, especially if you can source some recycled materials to work with! Start planning and asking friends and family if they have any materials left over from their last DIY project – you might be surprised at just how much you can source without spending a cent!

how to build an outdoor stone fire pit

Safety Considerations When Building an Outdoor Fire Pit:

Before we start the steps on how to build an outdoor stone fire pit, there are some safety notes you should pay attention to:

  1. You should check your local safety codes. Depending on where you live, you might find that you need approval for any new structures (and someimte that includes fire pits!) Also check what the envionmental legislation in your area says about having back yard fires – it would be a shame to go to all the effort of building your fire pit only to find out that it isn’t legal and you can’t use it!
  2. Location is super important. Look up! Make sure your fire will be away from tree branches, overhead power lines and any other structures such as awnings. Again, this is worth checking with your local governing body, but as a general rule, your fire pit should be at least 20 feet away from any flammable structures.
  3. Line your pit with either a thick steel ring or a ring or firebricks. These protect the blocks from the heat, which can cause them to dry out and break down prematurely.
  4. A fire pit should sit low to the ground, with walls rising no more than a foot off the ground. But for stability, the base of the wall must be buried below ground in a hole lined with gravel, providing drainage, which you can then pour a concrete base over, similar to how you would create the foundations of a garden shed or other small structure.
  5. Not so much a safety concern, but definitely a consideration… get some sort of cover for your fire pit! If you want to sit around the fire after a week of rein, you will be grateful I brought it up!

What do you need to build an Outdoor Fire Pit?

For your foundations, you will need:

  • A shovel
  • Gravel/blue metal or similar
  • Some old timber to create a formwork frame
  • Enough cement mix to create a solid base (depends on the size fo your fire pit)

On day 2, or once your cement has set, you will need:

  • Mortar
  • A mortar trowel
  • Your chosen stone, brick or pavers to be used
  • A good playlist for your ears to get you pumped for your next outdoor gathering!

Can you use any stone for a fire pit?

The type of stone you use for your fire pit needs to be selected by considering that they are going to become super heated. Really dense rock such as granite and marble don’t absorb moisture easily and can actually explode when exposed to high heat. The safest type of rock to build a fire pit with include sandstone, lava rocks, fire rated brick, recycled paving stones and concrete.

How to Build an Outdoor Stone Fire Pit:

Fire Pit Foundations:

Once you’ve selected the location for your firepit, it’s time to build the foundations. Mark out where your firepit will be situated and dig out a square, the desired width of your pit and approximately 200mm deep. Lay a bed of gravel in the hole, to allow drainage. Create yourself  a formwork frame with some scrap timber, such as old floorboards. You want this frame to be able to sit inside the hole that you’ve dug out – it’s going to keep the concrete in place when you pour it in until it sets. Hammer a few stakes in to hold your formwork in place to keep it from budging.

Pour the Concrete:

Use a wheelbarrow to pour cement into your formwork. Ideally, lay a piece of reinforcement metal about halfway up and continue to pour concrete on top until you reach the top of the dig out area. (ask around for an offcut of reinforcement if you don’t have any – someone you know should have some lying around!)

Build your Fire Pit:

The first layer of bricks/stones is the one you want to really take your time with. This layer needs to be perfectly level and if you get this bit right, the rest becomes so, so much easier! I suggest making your mortar mix slightly wetter than usual if you’re using materials such as firebrick, because it tends to absorb moisture, which can cause your mortar to dry out quickly and lead to cracking. The mortar acts as the glue to hold your stones together, but also helps you gets your layers level as it provides cushioning and a bit of wiggle room to play with.

The technique you use from here depends ont the type of stone or bricks you are using. Obviously square or rectangular shapes are pretty easy to layer around your wall, although be warned that any mistakes you make with these same-sized bricks will stand out a lot more than with different sized stones! If you are using stones that vary in shape and size, try alternating bigger and smaller ones as you go to create a nice aesthetic.

Once you’ve created that first layer, I recommend lining the inside of the wall with a row of fire bricks (also held in place with mortar). The fire bricks will work as a fire retardant on the inside of the wall and assist with the longevity of your fire pit. Continue the process of wall layers and firebricks until you’ve reached your desired height.
I like to use a black oven spray to paint the firebricks as they stand out a lot less when they are black (instead of white).

Capping the top of your Fire Pit:

 

This step isn’t essential, but it does add a lovely finish to the way your firepit looks. Consider a final layer of stone/bricks that slightly overlaps the inside and/or outside of your wall. This could be achieved by laying pavers or bricks on a different side to how they’ve been used in the wall, or turning stones to face a different direction. If you do let the capping layer overlap the inside of the wall slightly, it can provide just a little more wind protection too!

home made fire pit

Testing it Out!

Now comes the fun part!
As with any sort of campfire cooking, wind is your enemy, so pick a good day to christen your new fire pit! Depending on the size you’ve built, you can now get experimenting with all sorts of campfire cooking methods and equipment. Try hanging a dutch oven from a tripod over your fire pit or placing a cast iron grilling plate across the top of the wall for an instant hot plate. Oh, and make sure the fridge is stocked with beers, because your friends will be staying for a lot longer now!

build a backyard fire pit

 

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