Preparing the Site

• 1). Mark just outside the area where the sandbox will go, using wooden stakes and mason's string.
  
  
• 2). Dig at the lowest end of the sandbox site to the desired depth, usually 4 to 6 inches. Dig out the rest of the area, trying to stay as level as you can.
  
  
• 3). Remove the stakes and string outlining the excavation area.
  
  
• 4). Pound in a stake at the high point and outside the excavated area. Tie a piece of mason's line to the stake, long enough to reach anywhere in the excavated area. Put the line level onto the string.
  
  
• 5). Hold the line taut and level at the low side of the excavated area and measure the distance from the string to the ground. Once the measurement from the level string to anywhere in the excavate area matches the first measurement, it is level. Adjust high spots by digging out a little dirt, or put some back in to fill low spots.
  
  

Building the Sandbox

• 1). Spread sand inside the excavated area 4 inches wide and 1 inch deep along all four edges. The 4 x 4 boards that frame the sandbox sit on the sand, which makes leveling them much easier.
  
  
• 2). Level the boards with the 4-foot level, hammering down on the boards toward the high end to bring them down into level.
  
  
• 3). Lay the next course of 4 x 4's on top of the first, reversing the end to side joint pattern so they alternate with the boards beneath. Secure the two courses together by placing 6-inch timber screws every 3 feet all the way around the perimeter.
  
  
• 4). Lay the landscaping fabric down over the excavated area and overlapping the boards. Push it down on all four sides so it lies flat against the four walls and the bottom of the excavated area.
  
  
• 5). Lay the last course of 4 x 4's on top (sandwiching the landscaping fabric between the second and this final course) with the overlap of the joints opposite the second course. Secure the final course of boards using the 6-inch timber screws about every 3 feet.
  
  
• 6). Trim the landscaping fabric hanging outside the box using the utility knife, and fill the sandbox up.