How to Lay Flagstones in Mortar

Prepare the Area

• 1

  Pound stakes into the ground around the perimeter of where your flagstones are to be placed.

• 2

  Attach a string to all of the stakes, forming a string perimeter that will soon be the outline of your newly laid flagstones.

• 3

  Dig out the area inside the string down 6 inches from the surface.

• 4

  Place salt-treated 2-by-6 lumber around the edges of the string border. Set them on edge against the inner walls of the dug-out area. Drive stakes in front of the boards to hold them in place. Drive nails through the ends of the touching boards from one to the other, creating a solid barrier.

• 5

  Pour 4 inches of sand in the 6-inch hole that you dug and wet it down with a garden hose. Compress the sand with a hand tamper by pounding all of the sand down forcefully.

• 6

  Mix a mortar made of two parts sand and one part cement; add water until you have a stiff but manageable consistency.

Lay the Flagstone

• 7

  Pour mortar into a small section of the patio hole and level it to 1 consistent inch using a trowel.

• 8

  Set the flagstones where you want them to be and push them firmly into place. Wipe away any excess mortar on top of the flagstones with a wet sponge.

• 9

  Apply more mortar to another section of the patio and lay a new set of flagstones and wipe away any excess mortar. Continue this process until all of the flagstones are in place.

• 10

  Mix your grout according to the directions on the container and place it into a grout bag. The grout should be the right consistency to stay on a putty knife without running off, but it should not be in large clumps either. Squeeze the grout into the joints between the flagstones and smooth it into place using a damp sponge. Wipe away any excess grout using the clean end of the damp sponge.

• 11

  Wait a day for the grout to set. After 24 hours, mix nine parts water with one part muriatic acid to create a cleaning solution. Mix a five-gallon bucket with half a gallon of muriatic acid and four and a half gallons of water. Clean the flagstones with a sponge dipped in the mild acid solution to remove any film left from the grout application.