Flagstone Patio DIY

Why Install a Flagstone Patio?

Flagstone brings a character to outdoor spaces that manufactured stone simply can't replicate. Every piece is different in shape, colour, and texture, which means every installation ends up completely unique.

It works beautifully in both formal and relaxed settings, pairs naturally with gardens and planting beds, and develops a warmth over time that only natural stone can. If you want an outdoor space with personality and staying power, flagstone is hard to argue with.

How to Start

Flagstone patios are among the most rewarding DIY landscape projects, and one of the most personal, since every installation ends up completely unique. Before getting into measurements and materials, spend a moment on the design decisions that will shape the whole project.

How large do you want the patio to be, and will you use natural or manufactured stone? Are you going for a uniform, precise layout, or a more relaxed random pattern for a natural look? Would you like a contrasting border or an accent stone in a different colour at the centre? And when it comes to finishing the joints, are you planning to use Polymeric Sand or mortar?

Once you've answered those questions, take some time to explore different styles and combinations. Our design booklets at Silverthorn Landscape Supplies are a helpful starting point.

Then get your full measurements down: length, width, height, and all slopes or grade changes throughout the area. Don't forget to note whether any water features will be incorporated into the design.

Sketch out your plan before you order anything. A clear drawing with measurements, product choices, and any design accents marked will save you a lot of time and frustration once you're mid-build. Use our Materials Calculator to estimate how much product you'll need, and call or come in anytime if you'd like help with the math.

Tools You May Need

Paper & pen • Tape measure • Stakes & string • Marking paint • Square • Level • Shovel • Wheelbarrow • Rake • Gloves • Chisel • Safety glasses • Knee pads • Rubber mallet • Hose • Hand tamper • Broom

Additional Tools

4" piece of 2x4 wood • 2 pieces of ¾" - 1" pipe (for levelling)

Products You May Need

Flagstone • A-gravel • Limestone screenings • Paver restraints • Metal spikes • Gator Stone Dust Bond (polymeric stone dust)

Note: Advanced Performance Bedding (APB) is a two-in-one alternative to A-gravel and Limestone Screenings that self-compacts. Come in or give us a call to find out if it's right for your project.

Additional Machinery (optional)*

 Skidsteer • Stone Saw

*Make sure you are qualified to run any equipment you may rent, or have someone experienced with machinery come out and help.

Installation

1. Plan

Review the How to Start checklist and lock in your plan. Confirm measurements, product type, and quantities.

Note: When selecting flagstone for patio use, choose pieces that are a minimum of 1" thick. Thinner stone can work, but the risk of cracking under foot traffic increases significantly.

2. Preparation

Mark out the excavation area. Before digging, call the appropriate utility companies to locate any buried lines (phone, cable TV, internet, gas, hydro, waterlines, and city piping).

3. Excavate

Excavate to a minimum depth of 6"-10" depending on project type. Remove all loose soil, and excavate the sides at least 3" wider than the area you'll be laying flagstone on.

4. Base

Place A-gravel into the excavated area, compacting every 2" and grading as close as possible to the final project outline. Add and tamp in layers until height requirements are met. All installations should slope away from buildings for drainage (minimum 1" for every 10 feet). Stop the gravel base roughly 3" below the desired finished height.

5. Screening

With a solid compacted base in place, it's time to lay the Limestone Screenings. Position two 3/4"-1" diameter pipes on the compacted base so that flagstone laid on top will sit 3/8" above desired finished level. Spread screenings over and between the pipes, then pull the 2x4 board across to level them. Remove the pipes and fill any voids with additional screenings.

7. Laying Your Stone

Lay flagstone directly onto the screened bed. You can go for a uniform, precise arrangement or embrace a random pattern for a more natural aesthetic. If you're using accent stone or a contrasting border, lay those first and build the main field inward, cutting pieces to fit.

8. Cutting

Depending on your design and patio size, some flagstone will need to be cut to fit properly. Mark the pieces and cut them yourself (with proper safety gear and training) or bring them into Silverthorn and we'll handle the cuts for you. See Cutting under our Services for rates.

9. Edging

Once the patio is fully laid, install edge restraints to prevent lateral movement. Using Snap Edge and 10" metal spikes, run the restraints along the full perimeter and drive the spikes into the compacted base (not the soil, where they won't hold).

9. Finishing Touches

To increase durability, prevent weeds and insects from settling into the joints, and resist erosion on sloped installations, sweep Polymeric Stone Dust into all joints until they're flush with the surface. Clear each flagstone piece of any excess, then lightly mist the entire patio with a garden hose to seal the joints.

Note: Some specialty pavers are not compatible with Polymeric Sand, so confirm before applying. 

Ready to get started? Come in or call us & we'll help you put it all together.