Building a Flagstone Patio

Want to create the ultimate backyard escape?

Building a beautiful natural stone patio using flagstone is easier than you think and is a great DIY project. There’s no need for concrete or mortar using our simple guide for laying flagstone using the dry construction method. Laying flagstone using this method is quite forgiving, even for those without experience.

First let’s determine what you need to get started, starting with landscape supplies.

Materials List:

• Flagstone
• Road Crush
• 5mm Bedding Sand
• Landscape Fabric
• Landscape Fabric Pins
• Polymeric Joint Sand (Optional)
• Landscape Edging
• Ardox Spikes

Tools & Supply List:

• Rubber Mallet
• Tamper (can be rented at most hardware stores)
• Metal Shears
• String
• Garden Hose
• 4 Stakes
• 4 2×4’s
• Scrap wood plank
• Level & Measuring Tape
• Gloves and Safety Glasses
• Broom

How To Design Your Flagstone Patio

Flagstone is not only simple to install, it is also forgiving when it comes design. Due to the nature of flagstone, no single piece will be the same size. The sizing and shaping of flagstone is irregular and therefore you are able to create rustic charm without much thought or effort. It may be worth laying out a few square feet of flagstone to see how it will turn out, but in general you are working with what’s available.

This guide assumes the construction of a square or rectangular flagstone patio, but you could create any shape or even a stone pathway. In terms of colour, Ornamental Stone carries a wide selection of different types to flow with or accent your overall landscape design. Rundle Stone is our top choice as it’s locally sourced and therefore highly sustainable, it’s charcoal colour will go well with almost any design.

In this guide we recommend the use of polymeric joint sand instead of regular sand. It will help set the flagstone together and will prevent weeds without the use of landscape fabric and any potential bugs such as ants. It comes in a range of colours that can either contrast or match the flagstone colour. Another option for the cracks is to fill with soil and spread grass seed to create an even more rustic look, but this will come with extra maintenance.

How Much Flagstone, Sand & Gravel?

We recommend placing flagstone on a base of 6” of Road Gravel with 1” to 2” of 5mm Bedding Sand. To determine how much sand and gravel is needed, enter the square feet (width x length) of your patio along with the above depths into our handy Volume Calculator.

For the flagstone, you should use 2” thick pieces for long term durability. Ornamental stone carries this size of flagstone specifically meant for patios. One of our most popular choices is Rundle Flagstone, which is a great charcoal colour and is locally sourced from the Rockies.

Determining the amount of flagstone needed is quite easy if we consider most natural stone weighs about 150lbs per cubic foot:

Square Feet x 2” Depth / 12” = Cubic Feet

Cubic Feet x 150lb = LBS Needed

We could then convert into tons (divide by 2000); Ornamental Stone offers bulk pricing for larger flagstone quantities. If this last section lost you… no need to worry, please Contact Us and we can help you calculate the amount of flagstone, sand and gravel needed.

How To Build Your Flagstone Patio

Once you have all your supplies and materials ready, you are ready to start creating a base and placing your flagstone.

1. Choose a level spot for your natural stone patio, this will ensure that the surface of your finished project will turn out flat and flow into the surrounding landscaping.
2. Measure out the desired area for the flagstone patio. Use a tape measure to determine the length and width, using the four stakes in each corner and using the string to tie them together. This will create a rectangular or square outline for the patio.
3. Dig 10” deep around the inside perimeter of the string starting with a spade to create clean straight edges. Switch to a shovel to excavate the remaining sod and soil.
4. We recommend the use of aluminum paver edging around the outside perimeter of the excavated area. Place and cut as needed driving the spikes in every 2”. This edging will contain the flagstone and prevent shifting outwards.
5. Fill the excavated area with Road Gravel at a depth of 6”. Now we need to pack the gravel down to create a solid base that won’t shift over time. Using a tamper that can be rented is the most effective and easiest method for this step.
6. Take your scrap plank of wood and place in various areas to check the grade using your level. It won’t be perfect but aim to get a level reading on as many points as possible.
7. Once the gravel has been tamped down and checked for levelness, you can add the 5mm Bedding Sand at a depth of 2”. This will create a soft, forgiving base that allows the flagstone to be placed in. The flagstones will not all be exactly 2” thick, so will need to be adjusted as necessary to create flat finished surface.
8. Starting from one corner, start placing down your flagstones, keeping them spaced 0.25” to 0.5” apart depending on preference. As you place each flagstone you will need to tap them with the rubber mallet to help settle. Try to ensure you are keeping the top surfaces at a somewhat equal level and sand may need to be added or removed in some cases.
9. Once all the flagstone has been placed, pour the Polymeric Joint Sand around the patio and sweep into the cracks using a broom. Then spray with water using a garden hose and let cure overnight.

By this point you should be done your flagstone patio project. Your backyard will be the envy of all your friends and neighbours in Calgary!