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Many homes have fireplaces or propane stoves inside, but there’s nothing quite like enjoying a fire pit under the stars in your own backyard. On a cool night in the summer, you can cook up a feast of hot dogs over a fire pit, while in the chillier months, nothing beats a fireside snuggle in your most comfortable chair.
Of course, fire pit ideas can be as simple as a hole in the ground with stones haphazardly stacked around it. But in only a few hours, you can build a fire pit that is considerably safer and more attractive. Try these step-by-step instructions for making a fire pit out of retaining wall blocks, or opt for a variation using other materials.
Tools & Materials
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How to Build a Fire Pit With Retaining Wall Blocks
This simple fire pit project employs easy-to-find retaining wall blocks and tools you likely already have on hand. Retaining wall blocks are designed with a rear lip to interlock effortlessly—and without mortar—creating a secure wall with a uniform and polished look. You can find straight-sided bricks for use in a rectangular pit, or blocks with angled sides to form a round pit.
Step 1: Check local ordinances to ensure that fire pits are allowed in your area.
First things first. Satisfy yourself that building a fire pit won’t result in your getting burned with a fine from the local government. Contact the planning offices in your area to see if any restrictions apply. Only proceed once you have the necessary approvals or when you’re convinced that none are required.
Step 2: Choose a safe, sensible location for your fire pit.
Choose a location for your ring of fire that is on relatively flat ground and situated well away from flammable structures (typically 10 to 15 feet). Remember also to clear any tree branches that hang dangerously low. Before finalizing the spot, record the movement of wind at a few different times of day; the outcome to avoid is smoke billowing into your home’s interior through windows or doors.
Step 3: Stake out the shape and size of your DIY fire pit.
Decide how wide you want your fire pit to be—the recommended diameter for a round fire pit is between 36 and 44 inches—and use marking paint to outline the footprint. Accomplish this by driving a stake into the middle of the area where you want the fire pit to go. Tie a length of twine to the stake that is equal to half the planned diameter. Then walk around the stake in a circle, twine extended, painting the perimeter. If you’re planning to build a square or rectangular fire pit, make careful measurements and mark its footprint.
Step 4: Excavate at least 8 inches of dirt within the fire pit ring.
Now it’s time to excavate the ground within the circle you’ve drawn. Use a shovel to dig about 8 inches deep, or as much as 12 inches. If the yard is sloped, you might need to dig down deeper on one end to ensure your installation will be level.
Step 5: Fill the excavated area with a layer of sand.
Pour a 2-inch-thick layer of sand into the area you’ve excavated as a base. Tamp down the sand to compact and level it. If you don’t have a tamper, step on it to tamp it and then level the sand by going back and forth lightly with the back of a bow rake over the top.
Step 6: Begin laying the concrete retaining wall blocks.
Lay one course of concrete retaining wall blocks around the edge of the pit. If slight adjustments are necessary to make the blocks level with one another, tap them with a rubber mallet to establish the correct height.
Step 7: If needed, add construction adhesive to the wall blocks.
For a bit more peace of mind, you can use a fire-safe construction adhesive to bond the blocks together. This will ensure a solid structure that will withstand feet propping on it, but note that it will also make the fire pit more difficult to dismantle in the future.
Step 8: Continue laying the concrete retaining wall blocks.
Lay a second ring of staggered blocks above the initial one, attaching the two tiers with masonry adhesive, if desired. To promote air circulation around the fire, leave small, intermittently located gaps between the blocks.
Step 9: Add a layer of gravel on top of the sand and complete the installation.
Add about 4 inches of crushed stone within the cavity, then lay down your final two rings of blocks. Let the adhesive dry for approximately 2 days before enjoying your first fire.
Step 10: For best results, add a fire pit insert or liner.
Your fire pit should hold up just fine with retaining wall blocks, but once you’re done building the pit, consider inserting a steel fire ring (to match the pit’s inside dimensions). Doing so will extend the life of your blocks by preventing them from drying out prematurely.
You may find that you like the appearance of the steel ring. A variety of fire ring types are for sale, so be aware of the shapes and sizes. With fire rings, it makes sense to splurge on higher quality to ensure you’re getting the most protection. Local code might require a step like this, so be sure to check.
Alternatively, see the steps below for placing a layer of firebricks on the inside of your fire pit or as the main wall material.
DIY Fire Pit Variations
The steps above outline how to build a fire pit with retaining wall blocks, but you can also use other materials, including pavers and firebricks. Another option is to repurpose natural stones to create an attractive and inexpensive fire pit.
Line a Fire Pit With Firebricks
Also known as refractory bricks, firebricks are blocks of clay or ceramic material that can withstand high heat. They are an alternative to inserting a fire ring or liner, especially for a DIY fire pit that is an odd size or shape. Firebricks will resist cracking and add a layer of insulation between the fire’s heat and the exterior bricks, which are more likely to crack from the heat.
Look for curved firebricks to line a round fire pit, or rectangular bricks for a square or rectangular pit.
Firebrick Option 1
If you find a firebrick with the right shape and appearance, you can construct the entire fire pit with curved, slightly curved, or colored firebricks. Just beware that the kilning, construction, and density that help these bricks hold up to fire-high temperatures also add to their cost compared with retaining wall blocks of natural stone.
- Proceed with the steps above (1 through 5) about selecting and preparing a fire pit site.
- Begin lining the shape of the fire pit with firebricks to outline the fire pit’s footprint.
- Place firebricks end-to-end and butted up against each other. Use a level to ensure the tops of your bricks are aligned, setting them tightly against one another.
- Line the gaps between bricks with refractory cement.
- Leave a gap at four opposite points around the first layer (base layer) of bricks. You can use a smaller brick or cut bricks to leave a half-brick-size hole at each point for airflow.
- Follow the tips above for leveling and mortaring the fire pit walls as you go.
- Finish the inside of the pit with gravel while you still can easily reach inside before completing the wall’s full height.
Firebrick Option 2
Most DIYers opt to use firebricks only as the inside layer of the fire pit. This ensures good heat insulation, saves on costs, and provides more possibilities for the fire pit’s external appearance.
- Proceed with the steps above (1 through 5) about selecting and preparing a fire pit site.
- Begin lining the shape of the fire pit with firebricks to outline the fire pit’s footprint, butting the bricks up against each other, cementing, leveling, and providing airflow as described in the previous firebrick option.
- Finish the inside of the pit with gravel while you still can easily reach inside.
- Face the outside of the fire pit with your selected decorative brick or natural stone.
Build a Fire Pit With Natural Stone
Although a fire pit without a steel or firebrick liner is likely not as safe or durable as one with a lining, it can be easier and less expensive to build, especially if you source local stone. The stone works best if it is relatively flat.
- Complete the steps above (1 through 5) about selecting and preparing a fire pit site.
- Scour your property to repurpose flagstone or other natural materials, or visit a nearby stone yard to secure enough flat, paver-like stones to build your fire pit.
- Gather more stones than you think you will need to ensure you have enough stones to fit together properly; natural materials are less consistent in size and fit than pavers or firebricks.
- Fit the stones against each other as tightly as possible. You may have to try several combinations to get the right fit.
- Place small bits of broken stone to fill significant gaps in your fire pit walls; they will probably require mortar.
- Simply stack the stones or use mortar to secure them more firmly. Look for refractory mortar for the best heat resistance.
- Allow the mortar to dry before laying about 4 inches of crushed stone, lava rocks, or fire pit glass within the cavity.
Safety Tips for DIY Fire Pits
While it can be a fun weekend project, building a fire pit is a serious undertaking with high stakes for the safety of your friends and family. Fire pit safety must be top of mind through each step in the process to ensure a final product that offers not only enjoyment and beauty, but also a safe environment for all involved.
- Start by ensuring that your fire pit is built in a safe area, away from flammable structures and plant life.
- Select materials that are fire-resistant and safe for high-heat situations. This includes the stones, adhesives, and mortar you use to construct the fire pit.
- Build the pit carefully and solidly.
- When enjoying an evening around your pit, always have a fire extinguisher or water source nearby in case things get out of control.
- Do not use regular bricks to build a fire pit. They may crumble and degrade or, because they can contain trapped water and gases, they can even explode.
- Do not use river rocks as the base layer of your pit. They, too, can contain moisture that can explode.
- Use care while building. If a heavy block lands on your foot or if you get carried away with the rock chisel, it’s good to have someone nearby to administer first aid.
Final Thoughts
Nothing beats the charm and ambience of a backyard fire pit. Family and friends are drawn to the glow of the flames, and songs and roasting marshmallows will make memories that everyone will cherish forever. Gather a few supplies and put in an afternoon of endorphin-releasing labor, and you’ll be the family hero!
FAQs
Line the bottom of your fire pit with a 2-inch layer of sand. An excellent heat shield, sand is fireproof and helps to distribute heat around the entire pit. Top off your sand with a layer of gravel or firebricks.
You can build a fire pit on dirt as long as you add a layer of sand on top of the dirt, and then a layer of gravel on top of the sand.
Look for cinder blocks that are fire-rated to avoid this problem. Cinder blocks that are too dense may contain trapped water, which can cause the blocks to explode if the water turns to steam.
The least expensive fire pit to build is one using found materials—stones you source on your own property, for example. Otherwise, purchase fire-safe blocks from a home improvement store and buy just enough to build your fire pit two layers high. This should keep the cost under $60.
