Step 8: Cap the Blocks

Cap the Blocks for the Fire Pit
Photo: Kolin Smith
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Loosely arrange the cap pieces on top of the pit walls. (If you are using natural stone, try to arrange the pieces together like a puzzle.) Lay one stone edge over the next and mark the upper stone where they meet. Also, roughly mark the stone for a 2-inch overhang on the outside of the circle and an inch on the inside. Using a brick hammer and a chisel, score the stone on those marks. On thick natural stone, use a grinder fitted with a diamond blade to score it more deeply.

Lay the stone on a hard surface. Split it by hitting a chisel in the score mark, or by tapping against the stone's edge with the brick hammer until it breaks. Score and split each stone this way, moving around the circle in one direction until you've made a cap that fits together tightly.

If you're using blocks, glue the pieces on top of the wall. If you're using natural stone, combine the dry mortar with enough bonding additive—not water—to make a mix with a peanut-butter consistency.

Wet the wall with some bonding agent. Lay a large mound of mortar on two blocks. With the point of the trowel, make a groove across the mortar. Lay the capstone on top, push it down, then tap it with the rubber mallet to set and level it. Continue to lay the capstones in this manner until the wall is finished. Wait two days before lighting a fire.
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    Tools List

    • brick hammer
      Brick hammer
    • cold chisel
      Cold chisel
    • square spade
      Spade
    • masonry hoe
      Hoe
    • metal garden rake
      Steel rake
    • tamper
      Tamper
    • two-foot level
      2-foot level
    • four-foot level
      4-foot level
    • mallet
      Mallet
    • caulk gun
      Caulk gun
    • brick trowel
      Trowel
    • angle grinder
      Grinder

    Shopping List

    1. CAST-CONCRETE WALL STONES

    2. CAPSTONES

    3. STEEL CAMPFIRE RING
    The one we used here is from MARKSTAAR

    4. 3/4-INCH DRAINAGE GRAVEL

    5. PATIO BASE
    (stone dust)

    6. MASONRY ADHESIVE

    7. READY-MIX MORTAR
    (if needed) to cement a natural-stone cap onto the wall. A 40-pound bag is enough.

    8. CONCRETE BONDING ADDITIVE
    (aka "milk") to make the mortar more flexible.