Details Landscape Art is one of the premier landscape design-build firms in the North Bay, offering a wide range of hardscape products. We build patios, walkways, driveways and steps, using various materials including stamped concrete, brick, tile, decomposed granite, and colored brushed-finished concrete. Our specialty, however, is flagstone, either set in sand or road base, or mortared onto a concrete base
Flagstone mortared on a concrete base is preferable for a patio, since it is solid, the pieces don’t move as the subsoil moves, and holds up well to lots of foot traffic and patio furniture.
Once the area has been graded so that there is a gentle slope away from the house, the multi-step process begins with laying out the outline of the patio and steps according to the design. The forms are then installed, also sloping so that the top of concrete will carry water away from the foundation.
Then within the forms, the area is excavated to a depth of about seven to eight inches – allowing two inches of road base, three and a half to four inches of concrete, and about one and a half to two inches for flagstone and mortar. After the road base (which acts as kind of a shock absorber) is installed and compacted, a grid of 3/8” rebar is placed throughout the area. The rebar binds the concrete so that if there is a hairline crack, it won’t expand or shift.
The concrete is poured, floated flat, but intentionally left rough, for better mortar adhesion. The forms are then removed the next day and we are ready for flagstone.
We prefer using really thin flagstone – a little more expensive, but easier to work with, less labor, less mortar. We begin laying out pieces of stone, chipping, cutting with a diamond blade, and gradually putting together the ‘puzzle’, keeping the joints between the stones a uniform ¾ to one inch wide. We try to turn the stone so the nicest side is up, and mix and blend any color variations. It is an artistic process. It takes extra time, but makes a huge difference in the appearance of the finished product. We also try to place pieces on the perimeter that do not involve cutting so that the outside of the finished patio has a natural look with minimal cuts showing. Sometimes, if necessary to cut, we will score the underside of the stone and break it along the score line to avoid showing a perimeter cut. Again, extra time, but worth it.
When the puzzle is complete we then have a big cleanup project. The saw cutting of the stone has created a thick layer of stone dust throughout the area. Beginning at one end and working in a continuous direction, we lift each piece of stone and hose down the rough concrete underneath. The stone is replaced and the next stone is lifted and cleaned. This process continues until the entire patio is perfectly clean.
We return to the project when the area is completely dry and begin mortaring the stone down onto the concrete. We use mason’s mix enhanced with a bonding adhesive to strengthen the adherence of the stone. Each stone is leveled with the adjacent stones, so that the surface of the patio is perfectly flat – not level, but flat, since we want to maintain the gentle 1% slope away from the house. Any variance in the thickness of the stones is accounted for by using a little more or less mortar.
The mortared patio is allowed to dry and harden for a day or two, and we come back and grout the joints. We add a special grout color powder to the mason’s mix, so the grout is the same color as the flagstone. We usually go with a darker color grout, to allow for fading from the sun over time.
And now a little cleanup, placement of outdoor patio furniture, and time for a gathering of family and friends on a gorgeous flagstone patio!