Build your own stone barbecue

Good weather is synonymous with barbecues in the company of family and friends. The term barbecue can refer to both the grill and the cooking technique, but also indicates foods prepared in this way, as well as the informal outdoor gatherings at which they are enjoyed.

In this article we focus specifically on barbecue grills. Based on their structure, they can be portable or fixed, and depending on how they produce the heat needed for cooking, they can be fuelled by wood/charcoal, or powered by gas or electricity. Today we will see how to build your own built-in barbecue for the garden. The simplest one to make is the charcoal or wood-fired version, although it requires more time and skill to cook food compared with a gas or electric BBQ.

Stone barbecue: start with the design

We suggest you build a stone barbecue. Do you prefer bricks? You can create a DIY brick barbecue by following the same principles. Compared with a prefabricated model, in both cases you have the freedom to customise the shape, dimensions and finishes, perhaps reusing recycled materials that you have put aside.

Our DIY barbecue proposal is therefore just a starting point, but before you get on with the task of building your grill, take a little time to plan it. A simple pencil sketch on a piece of paper will make you think carefully about where to place the barbecue, what dimensions it should have, how much material you will need and so on. Starting off on the right foot reduces the likelihood of realising that something has gone wrong later on.

Where is the best location for your stone barbecue? Find a suitable spot where it will be comfortable and safe to use. The barbecue should stand on a stable surface that is larger than its own size, leaving you room to move around it while cooking, as well as a pathway to the dining table, kitchen, woodshed etc. Make sure it is at least 5 m away from tree foliage, flammable liquids/materials, your home and the edge of neighbouring properties. Speaking of distances, check whether your local council’s building regulations include any specific rules governing barbecues. If you live in a windy area, orient the grill perpendicular to the wind direction, so that burning embers aren't swept out of the firebox and into the surrounding spaces.

The DIY wood or charcoal-fired barbecue that we propose is a conventional structure consisting of a firebox, i.e. a hearth enclosed on three sides and containing the cooktop which will accommodate the wood burner (that produces the embers) and the brazier, i.e. the space for the bed of embers over which you place the grill grate for cooking food. The firebox in our design is approximately 70-80 cm high, is not equipped with a hood and rests on a U-shaped base, which is 80-85 cm high and built on existing paving or a pre-positioned concrete slab.

To determine the dimensions of the firebox, you can base them on the measurements of the grill grate with feet that you already have or intend to purchase. To determine the size of the barbecue, take into account your needs and also consider the construction method. In our design, the size of the cooktop is dictated by the available dimensions of the hollow clay planks, a special kind of long, thin perforated brick about 10 cm thick that will be used to form the cooktop.

The design doesn’t include a worktop, but you can create one, personalising your barbecue however you like. Instead of wood or charcoal, would you prefer to make a DIY gas-fired barbecue for more practical cooking? The structure will need to be modified, by providing a hotplate for cooking food and an enclosure underneath for the gas stove, which must be connected to an LPG cylinder or a domestic gas outlet.

Materials and equipment for a stone barbecue

Here are the materials you will need to build your DIY stone barbecue:

• Squared stone blocks for the base and firebox.

• Refractory bricks, which are resistant to high temperatures, for the firebox.

• Hollow clay planks for the cooktop.

• Ready-mixed masonry mortar (just add clean water to prepare it) for the base and firebox blocks.

• Ready-mixed refractory mortar for lining the firebox.

• Ready-mixed concrete and electrowelded mesh for reinforcing the concrete slab and cooktop.

If you prefer a brick barbecue, replace the stone blocks with solid bricks. Building with bricks is simpler and faster because they generally have a more regular shape and standard dimensions. As we often suggest, you can use recycled materials, but the most important thing is that they are clean so that the mortar adheres to them, so first scrub away any old mortar residue and earth with a wire brush.

Here is a rough list of equipment for making your own barbecue:

• Hoe, spade and shovel for digging.

• Wooden planks to build the formwork.

• Mixer drill for mixing mortar and concrete.

• Float for spreading mortar and concrete.

• Trowel and scale rule for spreading and levelling the concrete.

• Other: wheelbarrow, tape measure, hammer, carpentry nails, mixing bucket, chalk, string and wooden pegs, plumb line, level, screw clamps, brushes and protective work clothing.

One useful tool on your barbecue site is a transporter – which you can use instead of a wheelbarrow to transport stones, bricks, bags of powdered products and other heavy materials – and a power generator for running electrical equipment, such as a mixer, if you are far from a mains socket. The generator can also help you during garden parties by powering a mini fridge, sound system and so on: take a look at how to choose the most suitable power generator.

How to build a DIY stone barbecue

Start work on your DIY barbecue by making a reinforced concrete slab about 8-10 cm thick:

• Clear the area of any vegetation using a brushcutter; if there is only tall grass, cut it with a lawnmower.

• Using the hoe, mark out the perimeter of the hole for the concrete casting (in addition to the surface area of the slab, include the measurements of the formwork around it).

• Dig the hole and level the bottom: the depth depends on how thick the slab will be and how high you want it to protrude from the ground.

• Line the hole with the planks that will form the edges of the casting (formwork) and keep it in the desired shape until it sets.

• Mix the concrete in the bucket, pour some into the hole lined with formwork, lay the electrowelded mesh on top, then pour in the rest of the concrete.

• Level everything and wait at least 24 hours for it to dry, then remove the formwork.

Using chalk, mark the concrete with the shape of your barbecue base and start building the U-shaped stone wall:

• Prepare the masonry mortar and spread a layer onto the concrete slab.

• Lay the stones of the first course (row of blocks or bricks).

• Spread some mortar on top so that the first course of blocks doesn't touch the second and no empty spaces remain.

• Continue laying courses on top until the desired height is reached: this base supports the cooktop, which should be at a comfortable level for your height.

The base must have a flat surface, so to keep the courses as horizontal and regular as possible, stretch some string between some pegs as a reference and check that it’s horizontal using the level. You should also check the verticality of the wall using the plumb line.

In order to build a perfect stone wall, the blocks must be as square as possible. Working with rough-hewn stone (pieces of irregular shape and uneven size) or even with cobbles (which are rounded with no flat surfaces) requires considerably more skill and time. In any case, mount the stones in horizontal courses, ensuring that the vertical mortar joints (perpends) between stones in successive courses are offset rather than aligned above each other. You can insert smaller stone elements to reduce the spaces between the blocks. At the corners arrange the largest and most regular stones so that the back and side walls are interlocked (toothed): to ensure that the structure is solid, alternate a course of ‘stretchers’ (blocks laid end to end) with a course of ‘headers’ (blocks laid side to side). The same rules apply if you use bricks instead of stone blocks for your DIY barbecue.

It's time to lay the clay planks that cap the U-shaped base of the barbecue and act as temporary formwork – which will remain incorporated into the structure – for the concrete cast cooktop:

• Spread a layer of mortar on top of the stone base of your DIY barbecue.

• Lay the clay planks side by side, centring them with respect to the thickness of the walls.

• Create the sides of the formwork for casting the cooktop: the edge of the cooktop should be flush with the base of the barbecue.

• Prepare the concrete, then fill the holes in the clay planks as much as possible, as well as the lateral spaces between them and the formwork, so that they form one unit with the casting.

• Insert the electrowelded mesh and pour the concrete into the formwork.

• Level the concrete and let it dry.

At this point, build the firebox or hearth of your stone barbecue, aligning it with the U-shaped base underneath:

• Build the stone wall of the firebox, just as you did for the base.

• Mix the refractory mortar and cover the cooktop with the refractory bricks, then cover the internal walls of the hearth.

• Finish the top of the hearth by smoothing it with mortar and the float.

• Coat the edge of the cooktop with mortar to hide the clay planks.

The exposed faces of the stones of your DIY barbecue must be cleaned, and the same goes for the refractory brick covering. So before the mortar sets, finish the mortar joints, remove any projecting mortar with the trowel and – after it has partially set – clean it with a wire brush, then go over the entire stone or brick surface with a bricklayer's brush.

Is DIY your favourite pastime? Here are some ideas for making the most of your garden:

• Create a biopool that purifies the water itself, without chlorine.

• Build a tree house with your own hands.

• Give new life to pallets by turning them into furniture.

• Equip your garden with a trellis for climbing plants and a DIY compost bin for producing your own fertiliser.