How to Build a Round Block Pool
Construct a durable, perfectly circular backyard pool using a center-pivot layout, concrete footing, curved masonry walls, and a smooth sand-coved liner base.
- Read the tools, materials, safety notes, and steps below for free.
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🧰 Required Tools & Equipment
- ✓ Center pivot stake with radius arm
- ✓ Torpedo and 4-foot bubble levels
- ✓ Masonry trowel
- ✓ Shovel and pickaxe
- ✓ Hand tamper
- ✓ Angle grinder with diamond masonry blade
- ✓ Wheelbarrow and mortar pan
📦 Materials & Supplies
- ✓ Marking spray paint
- ✓ Concrete blocks or radius wall stones
- ✓ Type S mortar mix
- ✓ Concrete mix (for footing)
- ✓ #3 (3/8-inch) steel rebar
- ✓ Masonry sand
- ✓ Heavy-duty round vinyl pool liner
⚠️ Safety Checkpoints & Warnings
- • Call 811 to locate underground utility lines before digging any ground.
- • Wear heavy-duty work gloves, steel-toed boots, and eye protection when cutting masonry and mixing concrete.
- • Do not stand inside deep trenches or under unsupported block walls during construction.
📋 Step-by-Step Guide (6 Steps)
Lay Out the Circle and Excavate Ground
Drive a heavy metal stake into the exact center of your pool area. Attach a non-stretching radius line or pivot arm and rotate it 360 degrees while spraying a crisp perimeter line. Excavate the entire footprint down to solid, undisturbed subsoil, keeping the floor roughly level.
- • A clear, uniform circular pit with vertical outer dirt edges
- • Exposed subsoil free of grass, topsoil, and large roots
- • Using stretchy string which creates an oval perimeter
- • Leaving loose organic topsoil at the bottom of the excavation
Pour and Level the Ring Footing
Dig a 10-inch wide by 6-inch deep circular trench directly along the block line. Place two continuous rings of rebar elevated on rebar chairs inside the trench. Pour concrete into the trench, continuously checking and screeding it dead-level using a long bubble level rotated around the center stake.
- • A smooth, continuous circular concrete ring footing
- • Level bubble centered at every 45-degree interval around the entire ring
- • Failing to make the footing perfectly flat, causing entire wall courses to tilt
- • Letting concrete cure before leveling high spots
Lay the Base Course of Blocks
Spread a 1/2-inch bed of Type S mortar along the cured footing. Set each block radially, using your center pivot arm touching the interior face to ensure an identical distance from center. Tap each block level side-to-side and end-to-end with the previous block.
- • A complete, gapless circular ring of blocks
- • Every block inner face precisely kisses the rotating pivot arm without pushing it
- • Setting blocks without checking radial distance from the center point
- • Allowing mortar joints to vary widely in thickness
Build Wall Courses and Fill Cores
Lay subsequent courses in a running bond pattern so vertical joints are staggered. Insert vertical rebar dowels into block cavities aligned with footing anchors, and place horizontal rebar in bond-beam courses. Pour structural concrete grout into all block cores, tamping out air pockets until solid.
- • Staggered wall courses forming a smooth, plumb vertical cylinder
- • Block cores completely filled with consolidated concrete to the top rim
- • Stacking vertical seams directly over each other, weakening the wall
- • Leaving large hollow voids in the block cores
Install Sand Base and Form Perimeter Cove
Wheel clean masonry sand into the pool center and spread it evenly to a depth of 2 to 3 inches across the floor. Compact the flat area firmly with a hand tamper. Build a continuous 45-degree sand cove (6 to 8 inches high and wide) along the entire inside base where the floor meets the block wall.
- • A flat, footprint-resistant sand floor across the center
- • A smooth, continuous 45-degree triangular sand wedge banking up the interior wall perimeter
- • Using coarse gravel sand with sharp stones that can puncture the liner
- • Skipping the sand cove, leaving a sharp 90-degree corner that tears the liner under water pressure
Fit Liner, Smooth Wrinkles, and Fill
Drape the vinyl pool liner over the walls, centering the floor seam evenly. Secure the liner over the top edge with coping clips or heavy-duty clamps. Add 1 to 2 inches of water, then gently work barefoot from the center outward to push all wrinkles toward the perimeter coving before filling completely.
- • Liner resting smooth and taut against the sand base without floor wrinkles
- • Water level rising uniformly against horizontal block lines around the entire circumference
- • Letting water fill past 3 inches before removing floor wrinkles (water weight locks wrinkles permanently)
- • Pulling the liner too tightly over walls, causing it to bridge over corners instead of resting on sand
Credit: inspired by an original tutorial by Valmor — watch the original on YouTube.
Don’t have everything?
- No Center pivot stake with radius arm? Heavy metal pipe driven into center with measured steel cable
- No Hand tamper? Flat 8x8 wooden post end wrapped in rubber
- No Curved radius blocks? Standard rectangular cinder blocks miter-cut on outer corners with a diamond blade