Flagstone Patio Ideas

The cost of a flagstone patio varies widely depending on your location, the amount of flagstone needed, as well as the type and color of flagstone. You can expect to pay between $15 and $30 dollars per square foot. Because flagstone is expensive, many homeowners choose to use it in conjunction with other materials such as concrete, bricks or manufactured pavers.

How to Lay a Flagstone Patio

David Beaulieu is a landscaping expert and plant photographer, with 20 years of experience.

Johnathan C. Brewer II is a licensed general contractor specializing in kitchen, bath remodels, and general construction with two decades of professional experience.

• Working Time: 8 – 12 hrs
• Total Time: 8 – 12 hrs

• Skill Level: Beginner
• Estimated Cost: $3 – $5 per square foot

Laying flagstone patios in stone dust or sand, as opposed to mortar or concrete, is known as dry-set or sand-set. Dry construction is much easier for do-it-yourselfers because you can build directly on the ground, while mortared stone requires a concrete slab foundation to prevent cracking in the mortar. For a lasting installation, a dry-set stone patio does need a foundation, though. It’s best to start with several inches of compacted gravel, followed by a layer of stone dust, also called decomposed granite, or DG.

The DG is pulverized stone and contains small pieces along with gravel-size and sand-size particles. The variation in particle sizes allows the material to compact well. And while it is still loose, you can use it to level the stones, just as you would with sand. You can buy flagstone and DG at local stone yards and landscaping materials suppliers.

When choosing stone for the project, select the largest stones you can maneuver by hand, and choose them for consistent thickness and appearance. The stones should be at least 1 1/2 inches thick for strength; 2 inches thick is better. Note that “flagstone” merely describes the stones’ wide, flat shape; flagstone comes in many different types of stone.

Codes and Regulations

Check with your city’s building department to learn about rules and requirements that may pertain to your project. Chances are, you won’t need a building permit for this project, but you may need to gain approval from the zoning department, which governs land use.

Most important, call 8-1-1, the national “Call Before You Dig” hotline, to have all underground utility lines marked on your property. You must do this before breaking ground. The service is free but can take several days, so call well in advance of starting your project.

What You’ll Need

Equipment / Tools

• Tape measure
• 8 Stakes
• Small sledgehammer
• Mason’s line
• Line level
• Shovel
• Rake
• Carpenter’s level
• Hand tamp or plate compactor
• Broom
• Garden hose

Materials

• Compactible gravel
• Decomposed granite (stone dust)
• Flagstone
• Fill material (as desired)
• Long, straight 2×4 board

Instructions

Mark the Patio Edges

Set up mason’s lines to represent the perimeter of the patio. Drive two stakes at each corner, about 2 feet beyond the sides of the patio perimeter. Tie a mason’s line to opposing pairs of stakes to create a square or rectangular layout (use a square layout if the patio will be circular). You will have a total of four strings; the points where the strings intersect represent the corners of the patio area. This layout method allows you to excavate and prepare the entire patio area without having to move the stakes.

Square up the Layout

Confirm that the string layout is square by measuring diagonally between opposing corners (where the strings meet); the layout is square when the diagonal measurements are equal. Adjust the positions of the stakes, as needed, to square the layout.

Slope the Layout Strings

Level and slope the strings based on the position of the patio: The patio surface should be level from side to side (typically parallel to the house) and should slope down and away from the house from end to end at a rate of about 2 inches per 10 linear feet. For example, if the patio is 10 feet long, it will be 2 inches higher at the house end than at the opposite end. This ensures that surface water drains away from the house (or other structures). To level and slope the strings, place a line level on each layout string and adjust one end of the string up or down, as needed, so the line is perfectly level, then tie off the string. Keep in mind that all of the strings should be at the same height. Then, readjust the two strings running down the sides of the patio to set the correct slope. For a 10-foot-long patio, lower the strings 2 inches on the stakes at the lower end of the patio. Finally, adjust the perpendicular string on the lower end of the patio so it is even with ends of the sloped strings.

Excavate the Patio Area

Remove all grass and other vegetation in the patio area (defined by the strings), then excavate the soil to a depth of 6 inches plus the thickness of the flagstone. For example, if the flagstone is 2 inches thick, excavate a total of 8 inches. This is to make the patio flush with the surrounding ground; you can dig less deep if you want the stones to lie higher than the ground. Measure down from the strings to gauge the excavation depth. It’s usually easiest to dig to full depth right under the strings, then clear out the soil in between, checking with a long, straight 2×4 and a level to make sure the ground is level from side to side (it won’t be level from end to end because of the slope). Tamp the soil with a hand tamp or a rented plate compactor.

Tip

Don’t kill the grass! Move your piles of excavated turf and soil off of your grass within two days so you don’t over-stress it.

Install the Gravel Base

Add a 2-inch layer of compactible gravel over the patio area. Rake the gravel smooth and level, then tamp it thoroughly. Add two more inches, then smooth and tamp. As with the excavation, measure down from the strings to gauge the thickness of the gravel and to maintain the proper slope.

Add the DG Layer

Add a 2-inch layer of decomposed granite over the gravel base. Rake the DG smooth, and level it side-to-side with the long board and level. Tamp the layer thoroughly. Remove the stakes and mason’s lines.

Organize the Stones

Stack or lay out the stones you will use for the patio surface on a broad, flat area, such as the surrounding grass or a driveway. Arrange the pieces by size and shape so you can select them readily as you lay them into the patio.

Lay the Patio Stones

Place the stones onto the DG surface, starting at one end and working toward the other. Place the stones as close together as desired. You will fill the gaps later with sand, gravel, or even soil and grass or other plants. Vary the size, shape, and coloring of stones for a random pattern, which looks most natural.

Tip

Don’t worry too much about keeping a clean line around the edges of the patio: Meandering edges will be visually appealing and further the natural look of the final patio.

Level the Stones

Level each stone, as needed, by adding or removing DG underneath the stone. Each stone should be stable and at the same height as the surrounding stones. Stone edges that stick up create tripping hazards.

Fill the Gaps

Fill the gaps between stones with sand, DG, or gravel. Sweep the material across the patio with a broom to push it into the cracks. Spray the patio with a garden hose to settle the fill material, then sweep more filler across the stones to fill the gaps as desired. Alternatively, you can fill the gaps with a potting soil mix and plant grass or traffic-tolerant ground cover plants between stones.

Flagstone Patio Tips

Some of the stones in your dry-set patio inevitably will move over time, due to use and to seasonal freeze-thaw cycles. But fixing shifted stones is easy. Simply dig out the sand, gravel, or soil around a problem stone, then pry up the stone using your hands or a flat pry bar. If the stone is too high, remove some bed material from under the stone; if the stone is too low, add some bed material. Reposition the stone and make sure it’s flush with the surrounding stones, then repack the joints around the stone.

Flagstone Patio Ideas

• 

Flagstone is one of the best materials for patios primarily due to its narrow packed joints that allow water to permeate instead of running off. Flagstone patios also have a very natural, organic look due to their shape and earthy shades of browns, reds, grays and blues.

Most Popular Links

The most common types of flagstone used for paving patios are sandstone, slate and limestone. Flagstone provides a durable and naturally slip-resistant patio surface that will last for years.

Benefits of a Flagstone Patio:

• Natural look
• Durable
• Can be laid dry for a permeable surface
• Moss, grass or a hardy ground cover can be grown between the stones
• Rich color with natural variation

Flagstone Patio Patterns and Layout

Flagstones can be used to create a formal or informal patio. For a formal look, select cut flagstones and have them laid in a repeating pattern. For an informal look, select irregular flagstones and have them laid randomly. This informal style is often called crazy paving. Get flagstone design ideas with color tips, material match ups, steps, and more.

Random Rectangle Pattern

Selecting flagstone in a random rectangle pattern is ideal for creating a formal, organized look. The rectangle shape provides continuity in conjunction with the staggered joints that break up the monotony. When this pattern is mortared, it makes for a smooth surface for sliding chairs in and out from a dining table.

Irregular Pattern or Crazy Paving

For a more casual, organic appearance, an irregular flagstone pattern emphasizes the natural shape of the stone. Small stones or groundcover are used to fill the gaps, or it can be mortared. This layout may be more difficult to move patio furniture around on because of the rough stone edges and the series of small joints. Wide, sturdy wooden furniture is most suitable so that the chair and table legs don’t get stuck between the stones.

Popular Plants to Grow Between Flagstones

Growing plants in the small openings between flagstones will soften the look of a patio. Certain groundcovers and grasses are well suited, including these five popular types:

• Various Types of Thyme
• Baby Tears
• Dichondra
• Mint
• Sedum
• Moss

Sometimes the surface of a flagstone patio can become uneven. This problem is typically caused by improper installation or deep freezes that cause the ground to heave. Ask a professional installer how to avoid this issue. Learn more about flagstone maintenance.

• Pro Tip: Avoid furniture with feet that are incompatible with the joint size and planting in an on-grade flagstone patio. See Ideas for Flagstone Joints.

Flagstone Patio Prices:

The cost of a flagstone patio varies widely depending on your location, the amount of flagstone needed, as well as the type and color of flagstone. You can expect to pay between $15 and $30 dollars per square foot. Because flagstone is expensive, many homeowners choose to use it in conjunction with other materials such as concrete, bricks or manufactured pavers.

Flagstone patio prices also depend on how it is installed. Mortaring flagstones on top of a concrete slab is typically more expensive than dry laying the stones over a base of sand and gravel.

• Pro Tip: We start by looking at the intended use of the flagstone area. If it is to be used primarily for the main dining and entertaining area, we recommend that the flagstone is mortared directly to the concrete base underneath. This is because we can provide a surface that will accommodate patio furniture and traffic without the uneven surface that plants and gravel cause,” says Roger Haywood of Accent Landscapes in Colorado Springs, CO.

How to Install a Flagstone Patio:

Here is a general overview of how a flagstone patio is installed:

1. Prep and grade the area
2. Dig down 3-6 inches
3. Compact a gravel base
4. Top with decomposed granite
5. Lay flagstones like a puzzle
6. Cut stones to fit if needed
7. Level each individual stone
8. Fill the gaps between the stones

Laying flagstones requires a lot of hard work. Did you know stamped concrete can be used to achieve a similar look? Check out these design ideas for faux stone concrete patios.

Related Reading: