Mark Powers leveling out dry concrete mix with a scrap piece of 2x4
Photo: Kolin Smith

Step 3: Prep the Project Site

The mosaic should sit level with or slightly higher than the surrounding ground so that water won't collect on top of it; take this into account when selecting your project site. Dig out an area at least 1 foot larger than your mosaic on all sides to a depth of 6 to 8 inches. (This will ensure proper drainage of the base and create enough space around the mosaic to add edging.) Tamp 6 inches of paver base and a 1-inch layer of stone dust into the excavated area. Pour dry concrete mix into the center of the installation spot, and use a 2x4 to screed the mix to an even 2-inch layer that extends 2 inches beyond the mosaic's footprint on all sides.
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    Tools List

    • trenching spade
      Spade to dig out the base
    • 2x4
      2x4s to screed the concrete and hold a tarp in place as the mosaic dries
    • garden sprayer
      Garden sprayer or hose with fine-mist attachment
    • 2 nails and string
      Two large nails and string
    • garden spade
      Garden spade
    • 4x4s
      4x4 to set and level the stones. It should be about the length of the mosaic's radius so that you can work on one small section at a time.
    • mallet
      Rubber mallet
    • Natural Bristle Brush
      Paint brush to spread the topping mix.
    • mason's brush
      Stiff-bristled brush to shape and dress the topping mix.

    Shopping List

    1. Sand and scrap plywood to make a box in which to lay out the mosaic's design. (Or spread the sand on a plastic tarp.)

    2. Mosaic stones. Choose flat pebbles or cobbles in colors you like. We used green and slate black from the Signature Stones collection at Stone Decorative

    3. Paver base

    4. Stone dust

    5. Concrete mix, such as Quikrete.6. Topping mix. Also known as sand mix, it's finer than concrete mix and contains no aggregate. Quikrete and other companies make it. You'll add it like grout between the joints after laying the stones.

    7. Pavers, bricks, or bluestones to surround the mosaic and hold it in place.

    8. Plastic tarp or sheeting