How to Build a Flagstone Walkway

In this video, This Old House landscape contractor Roger Cook shows how to rescue an old stone walkway.

Pro Tip: Skimping on installation quality can cost you more in the long run. On one This Old House project, a homeowner’s existing flagstone pieces had been set directly in topsoil—and they had already sunk, creating a dangerous trip step. As the crew observed, when previous owners tried to fix the problem by switching to concrete, the result was an uneven patchwork that still caught visitors off guard. Investing in a proper base from the start avoids costly rework later.

Steps:

1. Remove the old flagstones and set aside.

2. Lay out two garden hoses to represent the shape and position of the new 3-foot-wide walkway.

3. Use an edger to cut into the lawn along both hoses.

4. Move the hoses out of the way and use a shovel to excavate the walkway. Dig down at least 4 inches.

5. Install steel edging along each side of the excavated walkway. Hammer in steel stakes to hold the edging in place.

6. Install a 2×4 stretcher every 6 to 8 feet to hold edging at precisely 3 feet apart.

7. Line the bottom of the excavated walkway with landscape fabric.

8. Spread about 3 inches of pea stone over the landscape fabric. Remove the 2×4 stretchers.

9. Set a flagstone into the pea stone with a downward twisting motion. Then tap down the flagstone with a rubber mallet. Repeat to set the remaining flagstones.

Pro Tip: For a longer-lasting walkway, consider building up a more robust base. According to This Old House Magazine, a proper flagstone walkway rests atop a compacted, 6-inch-thick base of unwashed, 2-inch-diameter modified stone, with a 1- to 2-inch-thick layer of masonry sand sandwiched between the base and the flagstone. The sand makes it easier to level the slabs and prevents them from rocking.