How to Make a Concrete Fire Pit
This article will show you how to make a fire pit for under $50
Find a nice spot in your yard away from overhead obstructions like trees, power lines and decks. Once your spot is chosen you want to dig down roughly 3"-4" and compact soil as much as possible. Once the ground is level you are able to add 2" of base stone which will help keep the concrete from having direct contact with with the ground.
Once your stone is added you are now able to set your forms in place. In this case I had some 3/4" ply wood left over from a different project. The outside dimensions can vary depending on your project and what you have on hand, but in my case I used 3' outside formwork with a 2.5' inside form. This form needs to set roughly 1-2" below ground, we will back fill this to make everything level after the concrete is placed and the forms are stripped.
Now that everything is leveled out you are ready to add rebar (I found this old fencing material in my shed which I cut to size). You want to try and center the rebar up as best as you can, as long as there is some reinforcement in your forms you should be fine. To keep your form work from shifting during your pour, you want to be sure to add bracing at the top so the forms don't bow/shift during the placement of the concrete.
Calculating the amount of concrete needed is pretty simple, there are plenty of online calculators out there that will tell you exactly how many bags you'll need. What ever this number is I'd add 2-3 (you can always take them back). In my case I calculated 16 60 lbs bags, I used 17.5. To make the top of the pit smooth you want to be sure to screed the top off and follow up with a float to feather it out.
To cure your concrete evenly you want to be sure to cover with a plastic tarp or trash bags, wetting it every 2-3 hours for 24 hours. After the 24 hour time period you can strip the forms by taking out the screws and continue to 'wet cure' the concrete for another 72 hours. This will guarantee the strength of the concrete and reduce the chances of cracking in the future.
After 1 week you are ready for your first bonfire! Enjoy.
- 3/4" ply wood (Home Depot)
- 2-1/2" screws (Home Depot)
- All Purpose Gravel (Home Depot)