Building on a Concrete Slab

• 1). Clean the slab with a solution of TSP and water. Allow the concrete to dry before proceeding.
  
  
• 2). Build a border by sawing down and attaching four two-by-fours together with hammer and nails so the two-by-fours form an outside border.
  
  
• 3). Mix the mortar according to the instructions and pour enough mortar to lay three to four flagstone tiles at a time. Spread the mortar around evenly with a trowel.
  
  
• 4). Set three to four flagstone tiles at a time on top of the mortar, butting the outside tiles against the two-by-four boards and leaving 1/4 inch of space between each of the tiles. The tiles should be even with the top of the two-by-fours. Repeat this process until all of the flagstone tiles have been set. For tiles that need to be cut, use a pencil to mark a line where your cutoff point is, and use a wet saw to make the necessary cut.
  
  
• 5). Allow the mortar to dry, mix the grout and spread the grout in the spaces between the tiles using a grout sponge. Once all spaces have been filled, allow the grout to dry for 24 hours.
  
  
• 6). Clean the surface of the flagstone tiles with a clean sponge.
  
  

Building with Sand and Gravel

• 1). Measure the area of the space in which you would like to install the flagstone tiles and mark the four corners of the border.
  
  
• 2). Excavate the soil within the border, about 6 inches deep into the ground. Use a shovel to level out the ground. The slope should run slightly away from your home.
  
  
• 3). Add a 4-inch layer of gravel on the entire bottom area and spread the gravel around evenly.
  
  
• 4). Compact the gravel down tightly using a plate compactor.
  
  
• 5). Install a two-by-four on each inner border by pounding the two-by-four against the inner edge with a hammer. You may need to saw the two-by-fours down to size first. Secure the two-by-fours to each other with a hammer and nails.
  
  
• 6). Pour a 2-inch layer of sand on top of the gravel and use a rake to spread the sand across evenly.
  
  
• 7). Set the flagstone tiles one at a time on top of the sand, leaving 1/4 inch of space between each tile. Butt the outside tiles against the outer two-by-four border. For tiles that need to be cut, use a pencil to mark a line where your cutoff point is, and use a wet saw to make the necessary cut.
  
  
• 8). Tap each flagstone tile with a rubber mallet to set it into place securely.
  
  
• 9). Place a level on top, once all tiles have been set, and ensure that the surface is level and even and not sloping toward any building structures.
  
  
• 10
  
  Fill the spaces between the tiles with polymetric sand and use a broom to ensure the sand is spread evenly.
  
  
• 11
  
  Spray the tiles and sand with a light mist of water and allow the polymetric sand to set for 24 hours before walking on the tiles.