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How to Prepare for a Flagstone Patio in 2017

Posted in: patio design, patio questions, how to build a patio, patio tips

James Moylan

Monday, January 30, 2017

curved flagstone patio, recessed hot tub, and Phantom retractable screened potio at night Clifton, VA (1).jpg

What are the first steps of installing a flagstone patio?

Flagstone patios are a great way to incorporate the beauty and uniqueness of natural stone into your outdoor living space. Because the process involves real stone with natural variations in thickness and dimensions, each flagstone patio is a unique creation. Although the process for actually building a flagstone patio is essentially the same, the patio built for this particular project reflects that every job yields a personalized result.

Free patio consultation by Design Builders, Inc.

Water Considerations

One of the most important considerations with any patio is water. A patio itself is not permeable, so whenever water hits it from any source, that water is going to run. This necessitates that the water is controlled in certain areas.

When in the planning phase, a build and design team must ensure the existing downspouts of the house have proper runoff. That way, water isn’t falling onto the patio itself. All the downspouts also need to be trenched ahead of time. This deliberate and strategic diverting of water is the most important consideration before actually starting the construction phase.

Also keep in mind that patios are typically built on a very gentle slant. This drop is approximately one-quarter inch for every foot away from the house. This slant allows gravity to naturally divert water away from the patio. In this way, you can strategically push water anywhere it needs to go by manipulating how that physical slant of the patio is constructed.

While this slant is not enough to necessarily be felt while using the patio, it does play an important and necessary part in controlling water runoff.


Excavation and Subsequent Layerspatio excavation in Clifton, Virginia

After the planning stage, the next step is excavation. This typically means digging down to about eight to inches below the finish grade. After that process is complete, a stone aggregate is placed next, after which four to six inches of concrete is poured.

At this point, the project is ready for mortaring on different pieces of flagstone onto the concrete.


Getting Everything Level

One key challenge of a patio install is ensuring that everything on the patio fits together despite the irregularities in the flagstone.

  • Flagstone: These pieces tend to be one to two inches thick with a fair amount of irregularities and variance in the stone.
  • Mortar bed: This can be anywhere from one-half inch to one inch thick. This depends partly on how thick the flagstone is.

Edgesflagstone patio with decorative brick border in Clifton, Virginia

One way to differentiate between a quick, cheap flagstone job and a more thorough high-quality job is with the edge work. As seen in this project, the front contains a brick border, and the back edging is done in a thermal cap bluestone.

These edges or “border pieces” give the job a finished, uniform look, but they also serve a functional purpose. They prevent cracking or chipping, and on steps where people are frequently walking, they keep the flagstone pieces from coming loose.

While the flagstone pieces are irregularly shaped, the edge caps are uniform, which lends the edging that clean, uniform, finished look.

For more information about the flagstone patio created for this job or how a flagstone patio could be incorporated into your outdoor living space, please contact a representative of Design Builders, Inc.