How To Make a Sandbox

It's Easy to Build One With Interlocking Blocks

Child playing in sandbox.
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To make this sandbox, you will need no lumber and no carpentry skills. What starts as a children's play area can be refilled later with topsoil to become a raised garden bed. Instead of wood, which rots and splinters, you'll use prefabricated interlocking blocks, the type sold to make low garden walls or retaining walls. You can find these at any garden center in attractive shades of concrete or faux stone.

Supplies Needed:

  • Prefabricated interlocking wall blocks
  • Masonry glue (sold with blocks)
  • Landscape fabric (non-woven, porous type)
  • Earth staples (sold with landscape fabric to hold it in place) 
  • Shovel for digging
  • Tamper (a tool used to compact a soil surface)
  • Carpenter's level
  • Play sand
  • Tarp, old bedspread, or screen

The project should take 3 to 5 hours to complete if you follow these instructions:

  1. Choose a wall block style that complements your garden. To make a sandbox, you'll want blocks with a flat, smooth top, so little knees won't get scraped. Curved blocks allow you to make round or kidney-shaped beds; straight blocks make straight lines. Most interlocking blocks for garden walls come in curved and straight versions, so you can mix the two for any shape. Two courses (layers) will make a sandbox 8 to 10 inches high. The bigger and taller your walls, the more play sand you'll need to fill the sandbox.
  1. Dig out the space. If your aim is to make a sandbox that is nice and deep for kids to play in (with well-loosened soil for that future raised garden bed, too), dig down 4 to 6 inches.
  2. Place landscape fabric at the bottom. Also called "weed barrier," landscape fabric lets water through but prevents insects, weeds, and small animals from coming up into the bed. You can find landscape fabric at any good home and garden supply shop. Leave slack on each side, so that you'll be able to tuck this extra material between the bottom and the next course to secure it. Or use earth staples (hairpin-like, curved, metal pins) to secure the fabric directly into the ground.
  1. Spread a layer of sand around the edges of the bed. This will help you level the low wall you will be building for your sandbox.
  2. Lay interlocking blocks on the outside edge. Settle the first course into the sand, using a tamper and a level to make sure it is straight and neat-looking. Apply a layer of masonry glue and then put on the next course. Add more courses later if you wish to make a sandbox with a higher wall.
  3. Fill the contained area with sand. To make a sandbox, what you'll want for sand will be labeled as "Play Sand" or "Sandbox Sand." Sterilized and sifted, it contains no large particles that children might swallow or choke on, and it will not stick to your child's skin as landscape sand or masonry sand will do.
  4. How much play sand do you need? If the size of your sandbox is 4 feet x 4 feet, to fill a 10-inch high surround adequately you'll need one half of a cubic yard of play sand (or a little over half a ton). To determine how much play sand to get, measure your contained area (depth x width x length in feet). Divide this number by 27 and you'll know how many cubic yards are required. Confirm it's correct with your sand supplier.
  5. When not in use, cover the sandbox. If you don't, wandering cats will use it as a litter box. Cut a plastic tarp to the size of the bed, or use an old bedspread. It is easy to remove for play, and a dark color such as brown will blend in. Alternatively, use a screen as a cover, so that sunshine can enter and act as a disinfectant.

    Variations:

    • Build a sandbox with plastic blocks. Mail order sources sell such blocks, made of heavy plastic to look like paving stones. These interlock with metal rods and are sturdy enough for a children's play area, yet they are lighter than masonry blocks. There is no need to dig down into the ground: Just assemble the blocks upon the ground or the grass, then add play sand.
    • Build a "sandbox" of dirt. Children too old for a sandbox (5 to 8 years) will thoroughly enjoy a "dirt box." Simply fill the bed area with good topsoil, and let the kids play in it for a season or two. This will be a magnet for kids, providing endless hours of playtime involving toy metal trucks and plastic army men. Warning: kids will get very, very dirty in a dirt box. But that's the fun of it.
    • Build a beach for adults. This idea from Dick Cavanaugh is a nice addition to waterfront gardens or a backyard's built-in pool. Dig down about 12 inches in a large area 7 feet x 9 feet adjoining the pool patio. Fill with clean landscape or builders' sand (you will need 2 1/2 cubic yards.) Replenish the sand each spring or as needed.