3-Tiered Propane Fire Pit

This project will create a 3-tiered propane fire pit. Each tier will be made of a different material, so you will be able to try out several new skills.  The bottom tier will show you how to create a flagstone covered base.  The middle tier will show you how to work with metal and burn a design into a metal ring.  The top tier will show you how to make a metal stud frame and cover it with tile.  You can use these same skills on any other project you may want to accomplish.  This project is based on a propane stub out I have in my back yard.  You can also use a propane tank or a natural gas stub out you may already have in your backyard.  More important, your fire pit can be made in any shape or material you desire.  I will highlight in this instructable some things to consider when making your own fire pit.  So, let’s get started.

I chose to use a kind of plastic wood material for the base frame of my fire pit.  It is easy to work with, and will stand up to the outdoor extremes.  If you choose a different material for your frame, just make sure it can handle the outdoor weather and wetness.  To start the base, take two 2in x 6in x 12ft boards then cut one board to 9ft long and leave the second board 12ft long.  When made into circles, one board will be slightly smaller than 3ft in diameter, and the second, slightly smaller than 4ft in diameter.  Start with the nine foot board.  Use a circular saw to cut a straight line into the back of the board 2 inches from a short end, and parallel to the short end of the board.  Do not cut all the way through the board.  The cut should be approximately an inch and a quarter deep leaving only 1/8in of the board still attached.  Make the same cut every 2 inches for the entire length of the 9ft board.  When you are done, you will be able to bend the board into a circle.  Be very careful, the board will be very easy to break at this point.  Apply outdoor grade construction adhesive (glue) into the gap of every cut made, and bend the board into a circle.  Also, apply glue to the ends of the board to make a complete circle. Use strong tape or strap to hold the board in a circular shape until the glue dries.  If the board breaks on a cutline, just add more glue and stick the broken ends together.  Do the same thing to the 12ft board.  Cut eight spacers from the left over cut for the 9ft board, so you can evenly space the two circles. Wait for the glue in the circle pieces to dry.  Glue and screw the spacers to the smaller circle then glue and screw the larger circle into place.  When you’re done you will have an approximate 4ft circle frame for your flagstone.

I used ceramic backer board found in any home store near the bathroom fixtures sales area.  This material is used as backer board in wet areas behind tile.  You can also use a cement board material.  It’s normally located in the same area of the store, and is used for the same purposes.  Start with a piece of ceramic board and screw it to the top of your wood frame.  Use outdoor construction glue in addition to screws to make a strong connection.  Using a scoring tool for ceramic board cut away the excess around the outside of the circle.  To do that, you just score the material with the tool, and snap off the excess pieces.  Make sure you glue and screw the ceramic board to the inner and outer circles along with the spacers for a good connection.  Before you completely cover the top of the frame, draw the outline of the inner circle on top of ceramic board.  Using a grinding wheel cut out the center of the ceramic board so it is even with the inner circle. Once that’s complete, use the remaining pieces of ceramic board to cover the rest of the top.  It’s okay to piece the ceramic board to completely cover the top of the frame.  This whole frame will be covered in flagstone.  Just use enough glue and screws to attach the ceramic board securely to the frame.  When you are done you should have a plastic wood doughnut just short of 4ft in diameter with cement board across the top. The last part of this step is to check to make sure the top of the base is level.  Use any available scrap wood and screw it to the bottom of the frame to make the top of the base level.

Use outdoor construction adhesive to glue pieces of flagstone to the top and sides of the frame.  Use any design and spacing you desire.  To fill in the larger spaces, glue stone chips and smaller pieces of stone into the spaces.  Make sure the top layer of stone overlaps the sides, and use a grinder to shape the stones to fit.  Mix a batch of mortar using the directions on the bag, and include any color you desire.  Using a putty knife, your fingers and any small tools, fill the cracks between the flagstones with mortar.  Be sure to pack the mortar tightly into the holes.  When the mortar completely dries, we want a single, solid base.  Don’t worry about getting extra mortar on the flagstone, we will clean that up later.  When you completely filled in all the gaps, let the mortar dry overnight.  When the mortar is dry, use muriatic acid and soft bristled brush to scrub the excess mortar off of the flagstone.  *** CAUTION *** Be sure to read all the instructions, and wear protective clothing and eyewear when handling muriatic acid.  It’s very dangerous stuff, but can be handled safely when you follow all directions and safety warnings.  If you are not sure about something, look it up on the web before continuing.  When you’re done cleaning all the mortar off the flagstone, hose it off one last time to clean off the remaining acid, and the base is complete.

Start by cutting two 5in x 1/8in thick pieces of flat steel 9ft long. Before cutting, make sure you cut the flat steel long enough so the circle fits on top of the base just outside the doughnut hole without any big gaps between the metal and the base.  Using the metal bender from my first inscrutable or similar tool, roll each piece of flat steel into a circle.  Clean and grind the short edges of the first piece of steel and weld into a closed circle. Using the first circle as a guide, weld the second piece of steel to the first circle.  Remember to clean and grind any edges on both pieces of metal that will touch for a good weld.  Weld both the inside and the outside of each joint for a good connection.  As always, check to make sure the top of the middle tier is level when it sits on top of the base.

Align the middle layer on the base and mark where you need an access hole for the gas shut off valve. Cut a hole in the metal for an access door to turn on and off the propane gas.  Use the piece you cut out to create a door with some hinges and a locking mechanism.  Bolt or weld the hinges and lock into place. Create a design template and draw the design on the metal rings. Using a welder or oxy-acetylene tank, cut the design into the metal ring.  To ensure I didn’t cut holes all the way through the middle ring, I adjusted the gas on my oxy-acetylene tanks to be cooler than needed to cut all the way through the metal.  With the torch cooler than required to cut, the cutline would fill itself back in verses cutting through the steel.  You can also just weld your design right onto the outside of the metal using welding rod. To attach the metal ring to the base, cut and bend a few metal strips that you can screw into the bottom base. Drill a hole in the metal strip for a screw, and weld the metal strips to the ring. Paint metal ring with a heat resistant fireplace quality paint. Screw the metal ring to the base making sure the top of the metal ring is level, and you are finished with the second tier.

To create the top tier, start with a metal frame that is a square surrounded by a circle. First cut 4 metal stud pieces to create a square so the rim of the copper fire bowl rests on top of the square.  Add 4 more metal stud pieces inside the square to create an octagon shape that supports the bowl.  Use self tapping screws to attach the studs together.  Take a full metal stud and cut the sides every 3 inches over the entire length.  Bend the stud into a circular shape that fits around the square.  To make sure the circle is as round as possible you can add a metal ring to the inside. I used a metal frame from a small trampoline to help make the circle round. Using self tapping screws, screw the circle to the square metal frame.  Start covering the frame with ceramic board by laying a piece over the top and screw it on. Continue adding pieces of ceramic board until the top is completely covered. Again you can piece the ceramic board as long as each piece is well attached. Cut a bunch of three-inch square ceramic board pieces and glue them one at a time to the side. Try to make this outer ring as round as possible. Use extra glue to fill in any gaps.  Remove any excess ceramic board from the top so that you have a perfect circle.  Flip the whole top over, and drill a hole in each corner of the hexagon to mark where the inside octagon is located.  Flip the top back over and draw a line between each of the holes.  Using a grinder with a cutoff wheel, cut out the inner hexagon.  Place the bowl in the center of the hexagon and place the top layer on top of the metal ring checking for level.  The next step will be tiling the top tier, but now, you can see the fire pit is coming together.

Tape all the cracks on the top tier using backer board tape. Make a batch of thin set mortar using the directions on the bag. Cover the entire top tier with a thin layer of mortar. Repeat this step enough times to get the side round with a flat surface all over. Let the top dry completely. Make a second batch of thin set to attach the tile to the top. Start laying tile at one end and work evenly across the top. It’s important to make sure the tile reaches all the way to the outer edge of the top. The inside edge will be covered by the rim of the bowl, so the tile does not have to be perfect on the inside. Work your way around the outside and cut off any excess tile. Use a grinding wheel to shape any tiles around the curve. Cut off any tiles that are too small to shape with the grinding wheel. We will come back later to fill in the spaces. To attach the tile to the sides of the top tier, work your way all around the outside of the sides in one direction. When you get to where the tiles meet you may have to cut the tiles so that they fit. When you’re done with the tile, let the top completely dry before going on. Now it’s time to come back and fill in the little pieces. Cut and shape little pieces of tile to fit any gaps that are missing around the edge. Glue the pieces in place using outdoor construction adhesive.  When all the holes have been filled, you are done with this step.

Cut little tabs from scrap angle iron and weld them to the 2nd-tier metal ring. Using self tapping screws, attach the top tile tier to the metal ring. Make a batch of grout using the directions on the bag, and grout the entire top. Using the instructions on the bag clean off the excess grout and let dry. You now have three tiers complete on your fire pit and just need to add gas.

Cut a hole in the side of the cement block that the gas line can fit through. The cement block will be used to support the bottom of the fire bowl. To connect the gas, start at your gas stub out and using appropriate pieces for gas and pipe compound, attach a flexible water heater hose to the gas stub out. Thread the other and of the water heater hose through the hole in the cement block. Drill a half-inch hole in the bottom of the fire bowl. Attach a pipefitting to the top and bottom of the copper bowl using a piece of threaded pipe. Make sure the pipefitting is tightly attached to the fire bowl. Drill several 1/4 inch holes around the pipefitting for drainage. Connect the pipefitting attached to the bottom of the fire bowl to the water heater hose using the pipe compound and pieces from the water heater kit. Since I used propane gas, I needed to use an aerator fitting before connecting the fire ring.  Any barbeque supply store will show you the piece you need. If required, put the aerator fitting at the bottom of the bowl. Attach the fire ring to the inside of the fire bowl using the instructions that come with the ring. Depending on whether you use propane or natural gas, it will change how you connect the ring. Once the ring is connected you are ready to test the fire pit. If there are any leaks in the gas connections, you must fix them now. When the gas is correctly connected it’s time to add the glass. First, fill the bottom layer of the fire bowl with the much cheaper barbecue rock. Place a 1in layer of decorative glass on top of the barbecue rock to complete your fire pit.   *** Warning *** Sometimes instructables keep you from picking weeds...  Not that its a bad thing...

If I had to do this again, I would have fixed a few boo boos...  First, technically, I braised the metal together.  I accidently used braising rod instead of welding rod, and end to end joints are much stronger when welded verse braised.  Second, I would have turned the top tier over when I tiled the side.  My tile slid down a little while it dried, and left me with a slightly larger "smile" around the edge.  However, all in all not too bad for a rookie...  Besides, it’s the boo boos that make the project a one of a kind, and something to remember.  I really hope it will not take me over a year to write my next instructable.  I have lots of projects completed and in the works...