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Build Your Own Garden Fire Pit

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Build Your Own Garden Fire Pit

Socialise outdoors – when it’s legal, obviously.

With the potential for lockdown lifting this spring, along with it comes the chance to finally have friends over again. Chances are though, we’re going to have to be outside when we do; for at least a while longer. During the last one, when we were allowed to socialise outside, our garden fire pit was invaluable.

This garden fire pit is cheap and simple to build. You’ll need to hunt around for an old oil drum but they’re usually easy enough to find on eBay, freecycle, gumtree or whatever you’re “free and cheap stuff people don’t want” website of choice might be. The rest of the materials that actually cost money are mostly for the gravel surround. So, if you’re not fussed about that then it could be a very cheap project; in the region of £30 or so.

For tools and materials, you’re going to need:

  • a garden fork and/or spade
  • bricklayers trowel
  • spirit level
  • tape measure
  • strong bucket
  • angle grinder (or another way to cut the barrel)
  • drill driver
  • stiff rake
  • hammer
  • hand saw
  • coach screws
  • clout nails
  • weed control fabric
  • 25kg bag of pea gravel
  • gravel boards
  • stone chips or gravel (enough to cover the area in bags laid flat)

Ground preparation

Do you like digging? Yes? Oh good, then you’ll love the first stage of this project. If not then, well… sorry there’s lots of digging. Them’s the breaks. To be fair, if you’re just planning on putting in the pit and not having a gravel surround then you can skip the levelling and flattening stage and jump straight to creating the fire pit.

Get digging
I’ll admit, this is the least fun part of the project.

Essentially, what you’re looking to do is remove any large rocks, roots (in a way that doesn’t harm the tree) and other debris from the ground so that you can get it flat and as close to level as possible. Start by turning over all the soil with a garden fork. I know it sounds obvious here but you really do need to be careful with your back when digging. Loosen everything in about the first 6 inches, more if the ground is particularly uneven.

Next, use a stiff rake to move the soil from any high points to fill up the lower areas; keep doing this until your ground is flat. Simple right? It can take a while but it’s very much worth doing – skipping this step will mean you get thin, or even bald patches in your gravel later. No one wants a bald patch, trust me.

Prepare your barrel

At this point you’re going to need to cut your barrel. This is probably the hardest part of this whole project, Use an angle grinder and appropriate PPE to cut the whole way around the circumference of the barrel about two thirds from one end. You can drill a bunch of holes in the larger part and use it as a garden incinerator. You may also want to light a fire in the part you’re using and get it hot enough to burn off the paint before you put it in the ground. The smoke from the paint won’t do much for your stone or brickwork (or lungs so keep a distance).

A circle marked on the ground in line marker shows where to dig.
I was fortunate that my shadow helped me out a fair bit on this project. Top bloke.

Once your ground is levelled out, mark the spot you’re planning to have the fire pit. Place the barrel on the ground where you want it, put a brick or piece of stone (depending on what you are planning to use) against the barrel and then draw out a larger circle, offset by the width of the brick.

Creating the fire pit

Guess what…? More digging! Your favourite… I remembered. Dig out the marked circle to a depth of around 150-200mm. A good way to gauge the depth is to keep dropping the barrel into the hole as you excavate soil and place a piece of stone next to it until the edge of the metal is just below the top surface of the stone. You’ll also want to go a little deeper so you can back fill the bottom with some pea gravel for drainage.

A hole is dug for the firepit  that is larger than the barrel.
Mr Shadow Crin – helpful as ever. I did most of the real work though.

You could actually make the hole even wider if you so wished. It’ll mean you need to use more concrete around the barrel in the next stage which adds cost. It does however, also add additional thermal mass which will mean your fire stays hot longer after it begins to burn down. Your call.

You can use any type of concrete to fill the cavity around the barrel. I used postfix because it’s easier and quicker. The concrete’s main purpose is to add thermal mass around the fire pit. This then absorbs the radiated heat from the fire and reradiates it as the fire dies down. It makes it marginally more thermally efficient and helps keep the fire hot between fuelling so also means you burn less wood. Honestly though, if your worried about fuel efficiency you should stop planning to build a fire pit because they just burn through wood at a rate of knots.

First put down a 25mm thick layer of pea gravel in the hole and drill a few drainage holes in the centre of the bottom of the barrel. Then, place the barrel on top of the gravel so that the space is even the whole way around. Pour in your concrete up to ground level. Make sure to tweak the position of the barrel for level before letting the concrete set.

One other reason for using postfix type concrete here is that you only have to wait the length of time it takes to make and drink a brew before you can move on to placing the blocks for your surround.

The fire pit surround

Stone blocks are dry laid to make sure they fit.
These stone blocks were reclaimed from the bottom of the garden where there used to be a small wall.

You can use anything you want for the surround really, as long as it’s dry. Really wet blocks are likely to crack or pop when you first light a fire so avoid those. I used some pieces of Yorkshire stone which I’d left to one side when I excavated the ground for the summerhouse build. Before you mix up and mortar, dry lay your surround to make sure all the pieces fit nicely. Cut any blocks to size with a bolster chisel and lump hammer. Don’t use a cutting disc on stone, it won’t look nice, it’s too clean of an edge.

Instructions on bricklaying is beyond the scope of this post but I’ll skirt over the steps for putting these down. First mix up some mortar. Put water in the bucket first, then add sand and cement in a 3:1 ratio. Mix until you have a peanut butter consistency. Find better instructions for doing this here.

Placing your blocks

Lay a thick bed of mortar on top of your concrete and spread it about with the point of your trowel. Then place the block on the mortar bed and tap it down with the end of your trowel handle until it sits level with an even bed all the way around the base. Add another bed of mortar beside the block you just laid, then take some mortar on your trowel and ‘butter’ the end of the next block you wish to place; essentially this just means getting a decent amount of mortar stuck to the end of the block in a sort of pyramid shape. Place this block by placing it onto the bed of mortar and pushing it up against the last block so the mortar fills the space between them.

Rinse and repeat until all blocks are laid. Then go around with a small pointing trowel (or whatever you have) and smooth over the joints, filling any gaps as you go.

Some people are probably going to say you should use some fireclay in the mortar mix to prevent cracking. This is absolutely a good idea but you don’t have to. I didn’t. My mortar did crack eventually (I’ve been using the firepit for a couple of years now) but it doesn’t cause an issue and if it gets any worse I’ll just do a bit of touch up pointing. Again, your call.

Finally, tip the remainder of the bag of pea gravel into the base of the barrel to aid with drainage. This completes the fire pit and if you’re not doing the gravel sitting area then you’re finished. Good work, my friend.

Sitting area

I’d highly recommend adding a sitting area to the fire pit. It looks nice, it’s easier to maintain and it dries out far quicker after the rain.

Gravel boards

Please don’t skip gravel boards. I know it seems like you could, but seriously, don’t. I see so many gravel drives and patios which thought they could manage without and within weeks half their gravel has distributed itself across the garden and pathways. Usually, I’d say you can’t fight entropy, but in this case you can, with gravel boards. Use them.

Start by measuring up the perimeter of your fire pit sitting area and producing a highly accurate and technical drawing from which to work, as pictured below. Then order enough gravel boards to completely surround the area that will contain gravel. Cut each of the pieces to length, not forgetting to account for the thickness of the timber. Then, lay the boards out around the area to check it all fits nicely before moving to the next stage.

If have some, or you don’t mind the additional cost, you should treat the cut ends of the boards with some ‘cut end’ wood preserver to stop water and other nasties getting into the timber.

If you have an area where the boards are holding back soil, I would recommend using some pea gravel for drainage. Dig out a little more soil behind the board and then back fill it with gravel once the board is in place. This will mean the soil isn’t directly against the wood and help it dry out more quickly after rain. Then use wooden stakes to hold the board in place against the soil and gravel.

Now it’s simple a case of fixing the remaining boards in place. Do this by attaching them to each other with coach screws. Drill a pilot hole before driving each screw to prevent splitting. Ideally, you should also be attaching the boards to some anchor points. As you can see in the pictures, I have a fence down one side so was able to screw through boards into this to fix them in place. If you don’t have something solid to fix the boards to, then I’d recommend driving some more stakes into the ground to prevent the boards from moving out of position.

Weed control

This is another thing I’ve seen people skip. Don’t! Why, oh why, would you do all this work and then have it ruined the first springtime when everything grows straight up through your gravel. I put mine down three years ago now and it’s needed almost zero maintenance besides raking up leaves in the autumn. A little work now will save lots of work later.

Roll out the fabric leaving extra against the gravel board. You want it so you can fold it over and have it come up about an inch from the ground. Continue rolling out pieces of fabric with at least 100mm of overlap, more is better. Try to avoid overlapping at all where possible; i.e. keep as much of the fabric in single straight pieces as you can. Fix the fabric to the floor using plastic ground pegs as you go.

Keep going until you’ve covered the whole area. I found it easiest to work from two outside edges towards the centre. If you’re ground is on a slight incline then over lap the pieces like you would roof tiles, this will mean any plants that did try to grow up would have to go downhill first, which they’re not inclined to do. Obviously, if you have too much of an incline then you probably didn’t do the first stage properly. Go back and do it again.

Securing the edges

You’ll need to make sure the fabric is fixed to the gravel boards securely. Otherwise, it’ll likely move over time and seeds and plants will find there way into the gap quicker than you could imagine.

As mentioned, you’ll want to fold down the rough edge of the fabric. This looks neater and will also help prevent fraying. Do this so that the fabric comes up the board about 25 mm. Make sure that the fabric goes right into the corner without putting tension on the fixing points. Then fix the fabric to the boards using galvanised clout nails; the sort that are used for roofing felt. These will hold the fabric securely and not perish in the damp conditions. You could also opt for a staple gun with some heavy duty galvanised staples, but I think nails are more secure.

If you’re really going for a tidy job, then use a mini blow torch (or a gas lighter) to melt any stray frayed edges. It looks nicer and it will stop them getting caught and pulling when brushing and raking.

Bonus stage: make a leaf cover

This is optional but recommended so the firepit doesn’t fill up with leaves in autumn. It also stops you falling into it when you’re not concentrating. Which I’ve never done. Really. Ok, just once.

You can use some of the pallet wood for this. Just cut the pieces to length, slightly longer than the diameter of your barrel but shorter than the inside of your stone work. Then use screws and exterior grade grab adhesive to fix two more pieces across the back to make a board. Mark a circle from the centre of the board and then cut around this with a jigsaw (once the adhesive has dried).

Laying the gravel

You’re on the home run now. You’re going to need enough gravel to have a good thick layer across the whole surface. A nice easy way to gauge this is to work out the area of your space and divide it by the surface area of one bag. Don’t skimp. A thin layer of gravel will firstly look bad and secondly mean the fabric underneath becomes damaged quickly.

Lay out the sealed bags evenly across the surface. Once they’re all in position you can begin cutting them open and pouring out the stone or gravel into the space the bag previously occupied. You’ll probably want some help with this part, it’s pretty exhausting. Every 3-4 bags rake the gravel even. If you’ve ordered your stone or gravel in a bulk bag then you’ll need to barrow it into the space, just dump out each load and rake it to the desired thickness each time. Keep going until the whole area has a good even thickness. Don’t forget to keep the pallet for your first fire!

Fire pit, fit for a king

Or if not a king, then someone who just really like being outside and burning stuff. To be fair, those aren’t mutually exclusive. Infact, I imagine kings of the past used to be outside burning stuff quite often, like villages in other countries. That’s how kings rolled way back when… right?

A completed fire pit with stone surround and gravel sitting area.
Don’t you want to get outside and build one of these immediately?

Anyway, I digress. Well done, your fire pit is complete. The only maintenance any of this really needs is to clear out ash from the bottom every few fires. If you don’t do this, it’ll get a thick wet layer in the bottom and lighting fires in it will become very difficult indeed.

If you use these instructions to build one of your own, please send pictures, I like seeing what people have done using the blog. For your next project, why not build yourself a secure bike shed for that bike you undoubtable impulse bought during the first lockdown? There’s even downloadable plans for that project. Enjoy your fires and let’s hope for an easier rest of 2021.

Crin

Crin

A lifelong fan of making and breaking things. If you can do it yourself, why wouldn't you?

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