Flagstone in Stone Dust or Sand


There are two basic ways of laying or setting "flagstone". One way is in a cement mortar on a concrete base; the other, a more simple way, is in Stone Dust.

Following are 4 simple steps for the completion of a well-built patio.

Tools Required

  • 2 lb. Hammer
  • Shovel
  • String
  • (4) Stakes
  • Level
  • 2x4 Straight Edge (8 Feet Long)
  • 2x4 Straight Edge (2 Feet Long)

Step 1 - Preparing Area

flagstone1.gifFirst decide where the patio is to be. Drive 4 stakes in ground, one at each corner of patio area. Decide at what level the finished patio will be and mark one stake at this point. Using a string and a level, mark all the other stakes for the same level allowing for a slight drainage away from the house. (Slope 2 inches in 10 feet)


The ground now must be graded so that the area is 3-inches below the marks on these stakes. This grading is accomplished by either or both of the following methods (A or B). If drainage is poor or for a better job, put in 3 inches of Crusher Run Bluestone and pack well before placing Stone Dust

Method "A" - Excavate (See Figure "A")

Where the level of the patio is going to be about the same level as the existing grade, the area must be dug out to depth of approximately 3 inches. If this is lawn area save some of the sod for jointing as described below in Step 4.

Method "B" - Excavate (See Figure "B")

Where the level of the finished patio is going to be above the level of the existing grade, the area must be filled up and tamped to within 3 inches of the marks on the stakes.

To retain this filled area, there will have to be a retaining wall of some sort or, more simply, more fill dirt extending off to the sides of the patio area and sloping down to the existing grade as show below in Figure "B". In some cases, where the existing grade is sloping more than is needed, you may have to use a combination of Methods A & B.

Step 2 - Preparing Base

Spread out damp Stone Dust to a depth below the finished patio level to coincide with the thickness of stone to be used. As you lay each stone you will have to do a certain amount of leveling for each stone as described in Step 3. Irwin Stone carries a complete line of flagstone in all different thicknesses. 1-1/2" thick or thicker stone is best suited for laying patios of this type. THE THICKER THE STONE, THE BETTER THE JOB.

Step 3 - Laying or Setting the Flagstone

Start at one corner to lay flagstones. Lay flagstones along tight string on finished grade. Using a wooden mallet or a 2 pound hammer and block of wood, tap stone into place. If stone is tapped below finished grade, raise stone and spread more stone dust under stone. Determine where more stone dust is needed by the impression the flagstone leaves in the stone dust. Be sure to fill all voids under the stone. Reset the stone and tap into place. Set the next stone. Set all stones along one edge of the patio using string and long straight edge to insure a level surface then set the rest of the stones. Use level on top of long straight edge for a long level. Continue on to Step 4.

Step 4 - Joints and Finishing

Sodding - Use a wedge shaped stock about 4-inches wide to press down the stone dust between the stones. Fill between the stones with topsoil to within approximately one inch of the tops. Cut sod into strips and press down between the stones. If you do not want grass growing between the stones, put down a layer of landscape fabric below the stone dust and packed stone dust between flagstones. Never fill between the flagstones with cement unless the flagstones are laid on a concrete base.

Seeding - Use wedge shaped stick to press top soil between the stones. Fill to within 1/2-inch of the top. Mix grass seed with topsoil, by volume, 1 to 1 of seed and topsoil. Mix well. Fill between the flagstones and press in with wedge shaped stick to level of flagstone.