Last year my grandma (Meme) finally took the plunge and decided she wanted a fire pit. I offered to do all of the research and planning and my brother volunteered to help dig because that involved him driving the 4x4 to haul dirt. Whatever works right? There weren't many examples or resources to go off of so we used our neighbors as a example and winged it. I think it turned out pretty well so I'm documenting it in the hopes of helping someone else.
4-6 man hours
Wheel barrow (optional)
Sand ~3-5 50lb bags of sand depending on the fire pit size
Decorative rocks for the outer ring
Piping for stoking the fire (optional)
Arguably the most important step in the fire pit creation process is choosing the perfect spot. This was pretty easy for us because we have had cookouts my entire life in the same location. Before the fire pit we used a cutoff bottom of a 55 gallon drum to contain the fire. We ended up moving the center of the pit by about 6 feet in from the shore so that we could put chairs around the full 360 degrees of the fire. This was important to get the maximum number of people around the fire.
To correctly size and locate the fire pit we placed rocks out in a circle to simulate the edge of the fire pit. We then lined the circle with lawn chairs and anything else to complete the ensemble. We ended up increasing the diameter of our fire pit by 2' to allow plenty of separation from the fire to the edge of the pit and the rocks and grass. This ended up being a wise decision because we can actually pull our chairs up close and put our feet in the warm sand.
Take a spade and inscribe a circle in the placeholder rocks. Remove the top layer of sod from your circle and take it somewhere that needs it (I'm sure you have a spot). Then start digging a bowl shaped hole. We ended up making the center around 2.5' deep and then gradually coming up to ground level at the edge of the circle. Remember there's going to be a layer of sand on top of this so keep the edge of the circle vertical for a few inches.
We also had a little helper name Riley!
We chose to incorporate a ventilation idea that my brother came up with. We have some old 2' sections of 6" diameter ceramic tile laying around that were used for septic laterals back in the day. They've been out of the ground for years and are assumed to be sterile :). After we finished digging the main pit we dug a channel for the pipe to fit in. We put one section of it basically horizontal with the end about 6" offset from the center of the fire pit and slightly protruding from the sand. We then cut angles on the end of that and the beginning of the next piece. This allowed us to place the second at an angle so it protruded out from the ground about 6" outside of the fire pit. Using this we can blow or use a billows to stoke the fire from a distance.
Make sure to pack the dirt by stepping on it or using a shovel so that it doesn't mix easily with the sand. We then put a 3-4" layer of sand in the fire pit. We used a rake to even it out and make it nice and smooth.
For the finishing touch add some decent sized rocks to cover fire pit circle where it transitions from sand to dirt/grass. We didn't have large enough rocks so we ended up using a couple layers to get the effect we wanted. If you can, make sure to choose rocks that haven't been in the water. The rocks can absorb water that can flash boil when exposed to enough heat, causing the rock to explode.