Making your concrete fire pit is fairly simple. You can make one of these in a few hours with minimal preparation and work, and for less than $50 in materials. The cement is poured and set between the two bowls using a bag of cement and various tools, as well as two bowls as the mold (one in and one out).
Then you simply finish and sand it, and you’ve got yourself a concrete fire pit!
This design has the advantage of being a cost-effective solution to create a weather-resistant concrete fire pit that will provide a modern and sleek style to your outdoor patio.
It’s also a strong portable fire pit that uses gel “Sterno” fuel to create a rapid 30-minute fire after a grilling session.
Materials and Tools:
- Mixture of concrete
- One extra-large bowl (ours was 18′′ in diameter) for external mold
- One large bowl (ours was 15′′ in diameter) for interior mold
- Paintbrush and non-stick cooking spray or vegetable oil
- Mixing bucket, large
- Masonry trowel, medium-duty
- Working with concrete requires the use of the following safety equipment:
- For sanding and grinding, wear a dust mask.
- Goggles or safety glasses
- Work gloves or refinishing
- Drop cloth (plastic or reusable)
- Exercise weights, for example, are heavy things (or you can use the rocks below)
- Coarse and fine-grit sandpaper or sanding pads
- Canisters of gel fireplace fuel
- Grill grate replacement (ours was 14 1/2′′ in diameter)
- Decorative stones that are not flammable
Casting the Bowl
Finding the correct materials and operating safely are the two most important aspects of this project. We utilized the largest mixing bowls we could locate for the primary fire basin. Extra-large alternatives can be found at your local restaurant or party supply store. You can use a stainless steel mixing bowl on the interior and a plastic punch bowl on the outside.
Working with concrete isn’t tough, but it does necessitate a certain amount of dexterity. For starters, it’s quite heavy and can be tough to mix by hand in large volumes. Second, it’s critical to employ the correct safety equipment when planning and carrying out your project. Cover your work surface with plastic and work outside or in a well-ventilated location.
1. After you’ve finished preparing everything, spray your molds with non-stick spray. This will aid in the release of the concrete once it has dried. It’s enough to apply a thin, even layer to the interior of the outer mold/outside of the inner mold.
2. Then you’ll need to make your concrete. It’s difficult to estimate how much you’ll need, but it’s better to make more at the start than to scramble to make more later. For this project, you can use approximately a third of a bag, adding water a little at a time until the mixture is thick and cookie batter-like. Make sure you’re wearing your protective equipment because this is when the majority of the particles and irritants are floating around.
3. The concrete mix should next be added to the outer mold with the trowel. Half-fill it, then examine the inner mold to see how high the concrete rises to the side. It’s fine to put the inner mold back in and out a few times as long as you don’t lose all of your non-stick sprays. (You can clean it and reapply it.) A companion or an additional pair of hands is useful in this situation. Then, to keep it in place, add weights or rocks. There are a few things to keep an eye out for:
- Make sure the inner mold is centered when you insert it so your bowl has an even thickness all the way around.
- For an even, symmetrical finished product, keep the bowls’ lips coplanar.
- Adjust the weights to create the largest inner bowl feasible while maintaining a robust framework. Make sure there’s enough room on the inside of the bowl for your gel canisters to fit beneath the lip.
4. Use something with a motor to vibrate the bowl to remove any air bubbles inside the mold for an extremely smooth finishing surface. You can also use a reciprocating saw without a blade here, but any powered sander, oscillating or rotary tool or even an immersion blender will work. Let the concrete cure according to the package guidelines until it has settled and everything is no longer moving. (about 48 hours).
Finishing the Bowl
- Carefully remove the concrete from the mold once it has hardened. You can use a rubber mallet to gently pound on mine, first removing the inner bowl, then detaching the outside bowl. Don’t be scared; it’s solid at this point, but be careful because it’s rather hefty.
- Clean up the top lip with a coarse sanding pad (60-80 grit) and give everything a well-rounded contour. Wear your safety glasses, gloves, and dust mask again because you’ll be generating a lot of tiny particulate dust.
- Finally, bring it outside and insert the gel fuel canisters. Mine came from a local fireplace/swimming pool/outdoor recreation business, but they’re also available in hardware and home improvement stores, as well as online.
- In the bowl, place the grill grate. You can use a 14.5′′ bottom grate for a Weber kettle grill (for the charcoal, not the cooking surface). If you can’t find one, you can use a hacksaw or grinder to trim a larger one down to size or make your own out of hardware cloth or steel mesh.
- Cover the grate with a layer of rocks after that. A lot of people purchase “Mexican beach pebbles” from a garden center. These are regularly used with fire, so we are confident they’ll withstand the heat and won’t burst into fiery shrapnel if used for an extended period. So, just make sure that the rocks you’re utilizing are suitable for the job.
- While the flames aren’t as large as a bonfire, the gel canisters produce a lot of heat and a lot of enjoyable ambiances.