In Ground Fire Pits
Create a fire pit where flames seem to burst from the earth. Discover design ideas and tips for success with in ground fire pits.
Enjoy the crackle of a backyard bonfire by adding an in ground fire pit to your yard. These types of fire pits contain the fire underground, so flames appear to leap from the earth. The blaze creates an optical delight that can be breathtaking on a dark night. In ground fire pits can be as simple as a hole dug in soil or as complex as a fire brick-lined pit built into a formal patio.
Underground fire pits eliminate some of the risks of their aboveground counterparts, like flames leaping high enough to ignite overhanging trees or burning embers flying high enough to land on nearby combustible surfaces. The reason sunken fire pits eliminate some of these risks is because they’re typically smaller in diameter and contain the flames more than aboveground fire pits.
On the other hand, in ground fire pits do present some unique risks. It’s easier for children or pets to stumble into the fire, so stringent adult supervision is required anytime you’re burning. If the fire pit area isn’t well-lit, anyone is at risk of falling into it. When the pit isn’t in use, it’s wise to have a cover to keep out weather and prevent anyone—or any critters—from tumbling into it.
Follow the same rules for siting an underground fire pit as you would any fire pit, keeping it at least 20 feet from nearby structures, shrubbery, or overhanging trees. Double-check local regulations for backyard burning to make sure your fire pit is legal and won’t cost you more in fines than in construction.
Most landscapers recommend that the base of a fire be positioned six to 12 inches below the surrounding grade. A fire that’s located deeper in the earth will warm fireside seating less than one that’s built closer to the grade.
If you plan to cook over an in ground fire pit, position the base of the fire so flames will reach the food to cook it and not just heat it. This is trickier if you’re planning to cook using a rotisserie, which typically suspends food well above flames. For skewer and grill cooking, positioning food in relationship to the fire is a snap.
The most basic in ground fire pit is a hole dug into the ground. Create a diameter that accommodates the number of folks you’ll typically have seated around your fire pit. A two- to three-foot-wide fire pit usually seats three to four people easily. Add another foot for every additional one to two people.
To dig an in ground fire pit, mark the center of the pit and measure outwards to a distance equal to half the total diameter in every direction. Mark the surrounding lawn and start digging. Excavate to a depth of six to 12 inches, depending on how deep you want your fire base. Be sure to create a level base in your fire pit.
Afterwards, excavate a smaller, three- to four-inch-deep circle inside the fire pit. This area should equal roughly one-third the fire pit diameter. For example, with a 24-inch-wide pit, dig an eight-inch circle in the center of the larger one. Fill this inner circle with rocks or gravel to create a natural sump area for drainage. Top the entire fire pit base with two inches of sand. Surround the outer edge of the in ground fire pit with stones or logs.
You can also create more costly and permanent in ground fire pits that are built into a patio. For these types of underground fire pits, be sure to use fire-rated bricks inside and around the fire pit, as well as fire-rated adhesives to attach these hardscape materials. If you’re creating an in ground fire pit in an existing concrete paver patio, make sure the pavers are fire-rated.