How to Flagstone Concrete Steps

Flagstone is a commonly used material for wall cladding and floors, mostly in exterior settings. While flagstone is available in several different varieties, the natural look is most common. As a natural material, flagstone offers a durable, strong, long-lasting finish that can suit just about any setting or environment. The application of flagstone to concrete steps is a generally straightforward task that can be successfully completed by using basic masonry tools.

Wheel barrow

Mortar mix

Shovel

Brick trowel

Flagstone

Masonry hammer

Angle grinder with masonry blade

2-foot level

Grout bag

Large sponge

Layout flagstone pieces over the concrete step treads (horizontal portion) in your desired pattern. Leave about a 1/2- to 3/4-inch gap between each stone, to allow for a grout joint. Trim the stones to fit as necessary, using an angle grinder; refer to the angle grinder owner's manual for safety and operation instructions.

Mix mortar in a wheel barrow (as directed on mortar packaging), using a shovel.

Lift a stone from the top step and apply about a 3/4-inch layer of mortar to the bottom side. Press it to the concrete step tread; press the stone hard enough so that the mortar joint between the stone and the step compresses to about 1/2-inch. Work your way across the step, using this method.

Repeat Step 3 on remaining concrete step treads, working your way from the top to the bottom of the stairs. Set a 2-foot level over the surface of the stones as you set them, to ensure a level step surface; correct the stones as necessary.

Allow the mortar to completely cure as directed on its packaging, before moving on.

Fill a grout bag about 3/4-full with mortar, and lightly twist the top of the bag closed.

Evenly apply the mortar to the joints between stones, using the grout bag.

Wipe any excess mortar from the stone joints using a large wet sponge; rinse the sponge in clean water as you work.