Instructables

40 Inch (Inner) Diameter Retaining Wall Fire Pit ~ $110

Picture of 40 Inch (Inner) Diameter Retaining Wall Fire Pit ~ $110
As stated in the title this fire pit cost me about $110 for the raw materials. The inner diameter is 40 in (102 cm) while the outer is 54 in (137 cm). I purchased materials from both Home Depot and Lowes and I recommend visiting both because they had different block colors and sizing if you want to create a variation of this pit.

Raw Materials: 6 bags of .5 cu ft of drainage gravel (Lowes)
                           42 Retaining Wall Blocks (Home Depot)
Tools Needed:
                            Rubber Mallet
                            Level
                            Shovel
                            Angle Grinder with concrete-ready blade (only needed if you get blocks that do not have two level faces)
 
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Step 1: Place 14 Blocks in Circle

Picture of Place 14 Blocks in Circle
You could use a string and two pencils to mark out a more perfect circle, but I found it easiest to just lay the blocks in the best circle I could. Then, use a shovel or a stick to mark the outer and inner edges of the blocks.

I would also like to note at this point that you could use any number of blocks for different size fire pits and 12 would actually be the easiest to set up because the angles work the best. I chose 14 simply because I liked that size.

Step 2: Remove Blocks, Dig, and Lay Gravel

Picture of Remove Blocks, Dig, and Lay Gravel
Dig out in between the two circles you marked to a depth of  2- 3 inches. Fill this with gravel. It will help when you need to level the blocks and it also helps with drainage.

Dig a hole in the center of the pit about 20 in deep and 15 inches in diameter. Fill this with gravel for drainage.

Note: My pit was located in an area with wood chips so the area already drained well, hence less drainage rocks were needed. If you have clay soil I would advise following the instructions from this old house on the trench/ hole depths. Or you can use your own discretion.
valcider11 months ago
Very nicely done.I'm looking to build something similar in my own backyard.This gives me a good start.Thank you!