What you'll need:
Concrete retaining blocks
Colored spray paint
Gravel or lava rocks, or fire bricks
Metal ring (optional)
Fire-resistant mortar or masonry adhesive (optional)
What you'll do:
1. Safety first. Before you take any other steps, you should check that firepits are allowed in your community and obtain any permits that may be required. Then keep these safety precautions in mind as you move forward:
Take 10. Build your fire pit at least 10 feet from anything else: your home, shed, fence, trees, pool, etc.
Look up. Nothing should be dangling over the fire pit, including tree branches and fairy string lights.
Check the wind. You need level ground and an open area, which could end up being a windy spot. You don't want to be sitting in a plume of smoke or letting it blow into your home.
Keep water nearby. Or a fire extinguisher, but your garden hose will do the trick if you keep it close.
2. Mark your space. Lay out the bottom ring of your stones in the grass or put down your metal fire ring — available at any big-box hardware store — where you want the fire pit to be. Most fire pits are 4 or 5 feet in diameter and 3-4 layers high. Once you decide on the right spot, remove the stones and mark the circle using your spray paint (or spray around the outside of the fire ring).
3. Dig in. Using your painted circle as a guide, dig your pit 6 to 12 inches deep. You want the bottom to be as flat and level as possible. Once that's done, you can pour in your gravel or lava rocks. Using these small rocks is important as they allow for drainage. Fill it up to grass level, or just below if you've dug a deeper pit.
Using a Metal Fire Ring
A metal fire ring is often recommended for DIY fire pits, especially if you’re burning wood, but they aren’t really necessary. However, if you choose to use one, you’ll have protection for your pit’s inner walls, which might crumble faster due to the stones coming directly into contact with flames. It can also make stacking your outer wall stones easier by giving you a solid structure to align them against.
Helpful hint: The type of rock you use to fill your pit is critical as some rocks can't take high heat or can trap steam and could explode! Avoid pea gravel, river rocks, and other porous stones, and stick with base or crushed-stone gravel, lava rock, or fire bricks.
4. Build up. Lay your first ring of stones. Tamp them down so they're flat and even. You might choose to cement them together with fire-resistant mortar, but it's not critical to do so at this level. When you're ready to put on the second layer, you can use some mortar or adhesive to be sure they stay in place. Offset the stones in the second layer so their edges are not lined up.
Repeat again for the third and final layer of outer stones. Tap stones with a rubber mallet if you're having trouble getting them tight together.
5. And finally … Fire it up! A few old newspapers and kindling followed by pieces of dry wood will get the party started. Pack some s'mores ingredients in a basket, grab your music player and a refreshing adult beverage, and you are all set. Enjoy!
Sources: A Beautiful Mess | This Old House | Bob Vila