Install a Flagstone Path

Once your walkway is laid out, measure the approximate length and determine the square footage of stone you’ll need. Add 10 percent as a safety margin; 20 percent if your path winds a lot.

Visit a home center or stone yard to check out flagstone options. While limestone is most common, flagstones are also made of sandstone, blue stone, and even granite. Avoid the 3- to 5-foot long monsters; they’re a bear to handle and most suitable for patios. Instead, opt for the more manageable flagstone “steppers” 1- to 3-inches thick and 1- to 2-feet long. You can buy flagstones at your home or garden center and haul them home in your trunk (don’t tax your shocks with more than 10 at a time). Or, have all you need delivered by a stone yard or quarry. If you buy from a home center, you can measure a typical piece of stone and estimate the total quantity you’ll need. But since you’ll be hauling stone in installments you need only worry about this on your last trip.

You’ll also need coarse sand as a bed for the flagstone. Home centers sell it in 50-pound bags or you can have a load delivered by the stone yard. Multiply the square footage by 3 inches to estimate the square-foot volume of coarse sand you’ll need. (A 50-pound bag equals about one-half cubic foot.)

Using a garden spade, dig along the edges first, then dig out the entire width of the path to a depth of 4 inches. Use a wheelbarrow to remove the soil. Use a garden rake to smooth the bottom of the walkway. As you dig, you may encounter roots. Use pruning shears to remove the small roots and a hatchet or axe for larger ones.

Lay landscape fabric to keep weeds from growing up through your path. Fit the fabric in the bottom of the hole as precisely as possible, using scissors to cut the fabric. Overlap pieces by at least 4 inches. As you work, splash on a bit of sand to hold the fabric in place.

Spread a bed of sand, smoothing it with a garden rake so the top of the layer is about 1–2 inches below grade. This bed provides a firm base for the flagstones and promotes drainage. Tamp the sand with a store-bought tamper or by pounding it with a 1-foot square piece of plywood attached to a 4 x 4 or a fence post.

Arrange the flagstones on top of the sand using a pleasing variety of shapes and sizes while maintaining about a one-inch gap between them. There is an art to this, so allow for plenty of trial and error.

Often, you’ll find the shape you need in your pile of stones. But every now and then, you’ll need to trim a stone to make it fit. Begin by marking your cut line with a thick pencil or piece of chalk. Wearing protective eyewear, chisel a quarter-inch-deep channel with a mason’s chisel and a hammer or, even better, a small sledgehammer. Set the stone on a short length of steel pipe, position the chisel on the groove and tap it with the hammer until the stone breaks.

Set the stones so the final surface is even. Given the varying thickness of the flagstones, you may have to scoop some sand out from under high stones with your hand or a trowel. Others you’ll have to raise by pushing more sand underneath. Use a carpenter’s level to create a smooth surface and consistent inclines. Wiggle each flag back and forth to settle them in.

Spread sand across the set flagstones. Use a utility broom to sweep it into the joints. Spray the pathway with water to settle the sand into the joints. Add more sand where needed.