Flagstone Patio – Cost to Install An Outstanding Flagstone Patio

Flagstone is one of the best ways to impress your guests come to your landscaping design. Due to its attractive shape, color, and natural look, flagstone embellishes your backyard and makes it unique instead of using rigidity materials like old blocks or concrete layouts. Moreover, thanks to its narrow joints, a flagstone patio provides a non-slip and permeable surface to protect you from fall accidents.

A flagstone patio is like a long-term investment for your house because of its low maintenance which will last your lifetime. To install a flagstone patio, there is more than one way for anyone to finish this project. In this article, there are some guidelines for you to have the work done by yourself. Also, this article will provide you with the average cost to install a flagstone patio in both ways of DIY and hiring a professional. You’ll need to consider which is better for you.

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  • What is Flagstone?
  • Pattern and Layout of Flagstone Patio
  • Tools You’ll Need
  • Install Flagstone Patio Project by Steps
  • Cost of Flagstone Patio Installation
  • Hiring local professionals



There are three common groups of flagstone which are separated into sedimentary stone, igneous stone, and metamorphic stone. In which, the sedimentary stones are formed by the pressure of a sediment layer, conclude the layer of sand and organic sediments.

sedimentary stone

While igneous stone is created when hot, molten material cools and solidifies, the metamorphic stone is a kind of stone that arises when heat, pressure, fluids, and strain combine to transform sedimentary or igneous stones into materials with distinct properties.

igneous stone

Under heat and pressure, the metamorphic flagstone is what converts sandstone to quartzite and limestone to marble.

Sandstone, slate, and limestone are three common types of flagstone people usually use for landscaping their patio. In which, the sandstone and limestone belong to sedimentary rocks which the former is formed by sand while the latter is formed and composed of calcite. Another one – slate – is one of the metamorphic stones with layers of minerals.

Whatever the ideas about using which types of stones for your flagstone patio are, all of them also provide homeowners a durable and permeable patio surface with a spectrum of various colors. Moreover, you can plant grass, moss, other green plants, or you can lay hardy sand between each stone to fill the gaps and make your flagstone patio a natural appearance.



Flagstones may be utilized to install both a formal and an informal patio. Choose cut flagstones and have them set in a repeating pattern for a more formal effect. Choose uneven flagstones and have them set randomly for a more casual vibe. Crazy pavement is a term used to describe this casual type of paving.

The surface of a flagstone patio can become uneven over time. This issue is usually caused by poor installation or by deep freezes that cause the earth to shift. Inquire with a competent installer about how to avoid this problem.

These are two specific ways to arrange your pattern patio:

Random Rectangle Pattern

A random rectangle pattern is perfect for producing a formal, ordered impression for your flagstone patio surface. The rectangle form combined with the staggered joints not only offers consistency but also breaks up the monotony of the patio landscape. The special point is that this pattern will construct a smug surface for your sliding dining set to be much easier because it’s been mortared before installation.

Irregular Pattern

Irregular pattern is an uneven flagstone patio design that accentuates the natural form of the stone for a more casual and warming appearance. To fill the gaps, you can place some small stones or lay a cover onto the ground surface, or you can decide to mortar it to avoid gaps between each stone of your flagstone patio. Because of the tiny joints as well as the uneven edge of the stone, many homeowners will get into trouble with this irregular pattern while moving the patio furniture.

You should choose the furniture set which is wooden for the flagstone patio to ensure the legs will not be stuck between the gaps of each stone.



There are particular materials and equipment you’ll need to construct a long-lasting and attractive flagstone patio, whether you’re doing it yourself or hiring a landscaping firm to do it. If you don’t have the right tools, you could end up with something that won’t last long.

Or find a professional for doing all the right things required

You’ll need some basic types of equipment for masonry project, include:

  • Masonry hammer
  • 8 wooden stakes (or steel)
  • Jointer
  • Wheelbarrow
  • Shovel (all kinds of shovel you have)
  • Measure tape
  • Line level
  • 4-foot level
  • Plate compactor
  • Hand tamper
  • Edge grinder
  • Garden hose (in addition)

In addition, you’ll also need to prepare some particular masonry materials for your flagstone patio installation project. The materials might include compactible gravel, straight 2×4 board, decomposed granite, materials to fill the gaps (plants, grass, moss, hardy sand, soft sand, etc.)



Installing a flagstone patio may significantly improve your house design and inspire your visitors to come to your house. As we discussed from the beginning, there is more than one way for you to finish the flagstone patio project. In the next part of this article, you’ll know one of the effective ways to install your own flagstone patio which is committed to longevity, high quality, and ease of installation.

Tip for you:Check your under-ground utilities before going to any digging work and call 811 for approval and make sure you’ll not break the under-ground utility lines in your local area. If you start your project yourself, you’ll not have to get any building permit but your landscaping firm does. And you also need permission from your local zoning department.

Or call us for all work you need to do – Green Arbor Landscaping

Step 1: Planning the flagstone patio ideas

For a long-term installation, a flagstone patio requires a good foundation. And aside from the obvious concerns such as patio placement, size, and form, there are a few more factors to consider:

  • Grade: You must construct your patio in such a way that it drains correctly, or you will face puddling issues later. Instead of creating a level patio, construct it at a modest slant to allow water to drain freely – about 1/8 inch per foot. Take notice of the property’s current landscaping drainage.
  • Stone size: The larger the stone, the less effort there will be in putting them together. Larger stone, on the other hand, is heavier, thicker, and more costly. So, select a stone size that is appropriate for you.
  • Stone thickness: If you choose the stone which is so thinner, the excessive weight will break your flagstone before installation. Flagstone that is thicker is heavier and more costly. If you’re creating a patio in your backyard, about 1.5 – 2 inches thick flagstone would be enough. If you’re going to create a driveway out of flagstone, use stone that is at least 2 inches thick and preferably thicker.

Step 2: Mark the Patio Edges and Square up the Layout

Start to measure the height of your patio yard and its slope to place the stakes at each corner. Tie the string to connect each pair of stakes and form a square or rectangle layout for your flagstone area. You’ll expect to have about four strings which each point is for you to follow and excavate the ground base on it without moving all the stakes.

Measure the diagonal among opposing corners to ensure that there are equal diagonal measurements. If not, adjust the stakes to make the layout square. Remember to keep your surface flat and the slop is just about 1/8 inch per foot to drainage.

Step 3: Excavate the area

Remove all the lives in your patio, including sod, grass, and plants. You’ll need to dig deep enough to fit 3-4 inches of the packed gravel base, 1 inch of leveling material, and the thickness of the pavers. That implies you’ll need to dig down around 7-8 inches in most situations. In case you want to lay the flagstone higher than the ground surface, you can excavate less deep than normal.

You may be able to clear the soil around the patio in some situations, but you must prepare ahead of time. If the patio is adjacent to a structure, don’t construct it too high or you’ll wind up with soil right up to the siding – a perfect breeding ground for termites. Use a straight 2×4 board to check out and remember to leave the room for concrete forms when digging.

Use a plate compactor to tamp the soil on the ground.

Step 4: Adding Gravel Base

The gravel base is essential unless you like an uneven patio. It will keep your patio flat in the long run and will support your stones so they do not fracture and shatter. This is the patio’s basis, so don’t scrimp on it if you want a professional-looking end product.

Add the gravel 2 inches at a time, packing it down thoroughly before adding more. Smooth the gravel first and level it, then tamp it by a plate compactor or a hand tamper.

Step 5:  Add the decomposed granite layer

Decomposed Granite is the finest material to utilize (DG). This material looks like sand, but it is considered to be better than sand because you can easily walk on it rather than sand. Similar to the soil, DG is made up of larger bits of sand (about 1-2mm diameter). However, weeds get a hard time growing in DG, so you don’t need to worry about it.

Smooth the DG thoroughly because this is the final layer before you place the flagstone, and grade it side to side by using mason lines replacing the stakes to get the grade correct. When it’s level, use the hose to wet it down and thoroughly pack it down. If necessary, level up again. When you finish, remove all the stakes and mason lines.

Step 6: Puzzle The Flagstone

Start by gathering the bigger stones and arranging them around the patio’s perimeter. Larger stones should be used on the outer since lesser stones will shift and move over time. Large stones will hold the smaller stones in place toward the center.

Add the rest of the stones on the DG ground surface toward the center of the patio. Place the various color, textures, shapes of each stone in random to make a natural feeling for your house. Add sand, grass, gravel to fill the gaps between stones.

Tip: If the stones are not smooth and you need to spend most effort to cut them, use a concrete saw equipped with a bigger diamond blade.

Step 7: Leveling the flagstone

Because the bottom of some flagstones is going to be uneven, you’ll have to add or remove some DG underneath the stone. You may have to pick up a stone and tweak it 5 or 6 times until it sits perfectly. Unless so, the stone edges which are uneven create tripping accidents for homeowners.

To level each stone, first place a 4′ level on it to check how it sits in relation to the grade you’ve established and the other stones. Then make any necessary changes. This process isn’t enjoyable, but if you take your time, it results in a highly professional finish.

Step 8: Fill the gaps

To fill the gaps, you may use whatever you wish. You may fill the spaces with dirt and plant moss or something else. Alternatively, you may just apply extra DG, which will help keep weeds away. Sand, grass, or gravel is also a great choice for this step.

No matter what you add, make sure to spray it down with a hose to seal in the stones, and you’re ready to enjoy the fruits of your labor!

Don’t hesitate to call us for a free estimate – (206) 265-2940



The cost of a flagstone patio installation varies greatly based on where you live, the number of flagstones required, the kind and color of flagstone used, and the condition of your yard surface. You should budget between $15 and $30 per square foot. Because flagstone is costly, many homeowners combine it with other materials such as concrete, bricks, or prefabricated pavers.

The flagstone patio installation labor cost is calculated by hour. With a flat patio surface, the cost can vary from $70 to the maximum of $90 per hour – equivalent to about 3.5 – 4 square feet to hire labor. The labor will take the responsibility for all the work, including planning the ideas, collecting the equipment and material. The labor you hire will also mark and excavate the patio of your outdoor area, add the gravel, edge border, and sand if you want, apply sand to the joints, etc.

You might need to expect to pay for the cost of materials and supplies for this project, includes cutting and grinding consumables, mortar, etc. This cost is about $2 per square foot. Also, the cost for flagstone patio equipment is required – between $55 to $80 for a project. Some particular equipment used for this project might include a wet masonry saw, a mortar box, and a plate compactor.


Flagstone patio installation is a heavy project that requires many efforts and masonry skills. You can choose to do it yourself or spend an amount of worthy money to have your natural flagstone patio with maintenance and no difficulties. Search some information about the local landscaping firm around your area in the Google site or their own site, as well as its contact information and reviews from other clients to check whether they’re doing well. When you finish choosing a firm, call them for the estimated cost and their building permit before going to make a contract.

Green Arbor Landscaping is the top ranking in the landscaping field in general, and the flagstone patio installation field in particular. With 35-year of quality service in landscaping, Green Abor Landscaping is the superior choice for all of your outdoor living needs. You can search for other clients’ comments about the Green Arbor service site which will absolutely satisfy your expectations with their experiences and enthusiasm. You can check some reviews below on the Google site:

Izzy Gaming:“We were having a hard time finding someone to do some work for us. It was a relatively small area that needed to be leveled out and we didn’t have the equipment to do it ourselves. We reached out to four different companies and either the price was astronomical, they were too busy with other larger projects to do ours, or they just never showed up. Green Arbor Landscaping & Maintenance responded to our request a within a few days and had someone out here to give an estimate within a week. They were very kind had no problem taking on the job and the price was very reasonable. They did great work and we will definitely be using them again!”

Killua Decks:“I was referred to Green Arbor Landscaping & Maintenance by a friend and I had a incredible experience, they did sod, bark and installed a couple of plants. It looks great and they were very good at communicating throughout the process.”

To contact Green Arbor for a free quote estimate here is some information that you might need:

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