Backyard Quartzite Flagstone Patio

This project is a dry-laid flagstone patio using natural quartzite stones.

I had been interested in the natural flagstone appearance for some time - and I always loved the idea of a stone firepit to spend summer weekends. However, I never really understood the practicalities of how to do it, with no experience in masonry or patio laying.

Dry-laid natural-stone masonry is a thousands-year-old home improvement project, but still there are not too many resources that I could easily find of the techniques. I was able to do the entire project myself, and very pleased with how it turned out.

My goal for this article is to provide a good overview of the multi-step process, and dive into a few hard-earned lessons.

Raw Materials

• 5-6 Tons of Quartzite Flagstone 1-2” Thick
• 4" Deep of 5/8" Crushed Minus Gravel with Fines
• 1-2" Deep of Sand

Foundation Stage

• Construction String and Line Level
• Hand Tamper
• Vibratory Plate Compactor (rental)
• Gravel Rake
• Wood stakes 2”x2”
• 1” OD PVC Pipe

Puzzle Stage

• Tarp
• Multi-Angle Measuring Ruler
• PPE: Knee Pads, N95 mask (with valve), safety glasses, ear protection, gloves, steel toe shoes.
• Cutting: 7.5” inch Makita blade, 7.5” angle grinder, mason hammer,

Level Stage

• Construction String and Line Level
• Thin Wood Stakes
• Plane Laser Level, Laser Mini Tripod, Reflective Target
• Collection of Wood Stakes
• GRABO Suction Tool
• Industrial Push Broom

The initiating moment for this project was an endcap display at Costco in summer 2020.  An employee told the story that there was a COVID-related supply glut since typical stores were not buying, and Costco was able to get it cheap.  With some quick research on quartzite flagstone prices – that seemed like a pretty-steep discount. In hindsight I have seen similar prices sustained into 2021/2022, but regardless it gave me the urgency to purchase 5 tons that weekend.

Now to get from step 1 to step 2, I highly recommend having a wife who will remember that you impulse purchased 5 tons of flagstone, and is willing to remind you of certain promises that were made whenever she sees the stack of stones in the backyard.

The rough initial shape of the patio was two connected circles (two circles with 20’ and 16’ diameters, with ten feet between their centers), with a 5’ outer diameter firepit centered at the larger circle. This is a good moment to check your local fire codes, to ensure the pit is a sufficient distance from the house and from any overhanging limbs.

This rough geometry was a good starting point, and with construction spray paint (see blue and orange paint in image) I was able to test out how it looked to review from different angles.  Also this geometry made it easier to estimate the area, and plan for the volume of sand and gravel and (additional) stone. I continued the curves of the shape to connect to the under-deck-patio (see slight white spray paint in image). 

Then I smoothed out the circles to a less symmetrical tear-drop shape, (sketching with a stake in the dirt) mostly checking with the overhead view from the second floor.  Once I was content, I hammered stakes along the perimeter every 6-feet or so, so I would not lose track of the shape if the tractor or kids or dog knocked it down. 

Planning the Base -

The base of the foundation on the underlying dirt was 4-5 inches depth of 5/8 inch gravel with fines. Note you can get gravel with or without fines, but I recommend gettings it with fines. Fines are the increasingly small dust mixed with the gravel, and greatly helps for the compaction of the gravel layer. The next level was 1 inch of sand, then finally the 1-2” thick flagstone. That totals to about 6-7 inches from top of flagstone surface to the dirt beneath. A tractor was used to dig the necessary earth, to get 6-7 inches deep.

The stakes and dumping gravel –

Iplaced a collection of 2x2 wooden stakes throughout the planned patio area to help track and maintain the level. I worked to level the top of all stakes in a 2D plane, with the slight incline downwards towards the lower part of my garden for drainage. 

The angle I was seeking was 1 inch down for every 10ft. I used one string to measure out the correct decline (see orange string in image) and then added lines perpendicular off that center level and just barely touching it. Then the stakes themselves were marked as rulers with 2 in increments – to track depths of different areas as I dumped layer after layer of gravel. I smoothed the gravel around with a gravel rake, a necessary tool for the task.

Note that by the final stone-leveling stage, I had invested in a 2D plane laser, which I would have utilized for this step as well.

The compacting –

Once all the necessary gravel was on there, I rented a Home Depot compactor to compact it into place. I highly recommend renting the compactor, since it is only needed an couple hours or so, and it allows you to achieve a smoothness to the patio. I had a hand tamper as well, which was good to have for tamping later around the edges, but not sure the occasional use justified its cost.

The sand –

Once the gravel base was compacted,the sand was installed at a uniform thickness of 1 inch on top of the gravel. To maintain a 1 inch thickness I placed a series of 1 in Outer Diameter PVC pipe on the top gravel surface, then with a long and straight 2x4, I scraped on top of these PVC pipes, so that everything over 1in was knocked down to flat surface, and all areas too low were visually apparent. As the sand provided the more "fluid" base, I did not attempt to compact the sand afterwards.

At this point I was really careful not to step on the sand to disturb the perfect surface. Encouraging the kids to treat the sand as if it were lava was fairly effective for the first couple weeks, but as it took me about a year to cover the last patch of sand – patches of the surface were eventually completely textured with the kids and the dog and my footprints. In hindsight - I don’t think maintaining a perfect surface was ever a useful pursuit. Even with random distribution of footprints, the sand will stay fairly evenly distributed, and the variety of the flagstone thickness you will have to adjust the amount of sand anyway.

The next step is quite literally a puzzle. Now you will actually be moving stones into place. A decent amount of planning can hopefully minimize wasted energy.

Save your Back

Also with lifting and moving stones, the right PPE is really helpful here. When you are lifting, a multipack of good leather work gloves is key (another Costco buy). Also avoiding a back injury is probably the most important detail to avoid abandoning this project mid-way - I always used a back brace during the work and spent most nights applying ice, stretching my back and consuming Advil. 

Organizing Stones for Completing the Puzzle –

Similar to a puzzle, having all the pieces turned up and all corners visible makes the whole thing easier. That is especially true when the puzzle pieces are 20-40 lbs and constantly moving the wrong pieces out of the way could slow you down by weeks. My final patio had over 300 stones. I organized all the stones on a set of tarps, grouping them based on similar shapes and sizes and angles.  

Unlike the jigsaw puzzle metaphor, moving a piece into position just to see if it fits, will quickly exhaust you at 40lb a piece. To avoid that – I developed a routine of trying to measure the gap angle and shape. I used a multi-angle measuring ruler – the purchase which probably saved me the most pain per dollar. The tool has multiple segments screwed together – so you can adjust the angle and shape, pivoting about the screw points, and once you have copied the outline, tighten the screws fix it into place. There are several different cheap versions online. 

My simple process was (1) I would try to find the deepest angle exposed in a gap (2) adjust the ruler angles to the shape of the gap (3) wander around the organized tarp holding the ruler up to appropriate pieces (4) finally carry a stone with similar angle and shape and attempt to fit.

The advice from a few sources was to start laying the stones around the perimeter, so you can place the heaviest ones that will not move under the traffic and will maintain the border.  

Background About Quartzite –

During the cutting phase, the type of stone you have will affect your process. During my research I found that quartzite is described as the most expensive/durable/beautiful option.  Firstly I love the appearance – it has a really unique sheen that is hard to describe or show in a photo – mixture of greys, oranges, and blues – that increase in contrast in the rain and shine like reflective in the sun. Some pieces are very shiny and textured, while others are smoother with a matte finish. 

Quartzite is a metamorphic rock, which originated as sandstone, then was compressed for a long time under intense heat and pressure. This is important for working with Quartzite for two reasons (1) Quartzite is extremely hard and registers a Mohs Hardness Scale of 8 out of 10, harder than glass, harder than granite, which means it must be cut by diamond. (2) As it originated as sandstone, there are occasional layers of impurities, which manifest as weak seams between the rigid stone. These invisible seams will become apparent when upon impact the rock with break in two in surprising and frustrating locations

While some YouTube videos show splitting a rock with only a hammer, I abandoned the hammer as I seemed to ruin stones 10-20% of the time. That frustration is why I migrated to exclusively cutting with a saw.

Cutting to Size –

Most of the stones will require some level of cutting to fit to size. This step is likely more work and more time (and more dust) than all the others.

My aim was to have gaps no smaller than my pinky and no bigger than my thumb, which is a very tight fit, and the tighter the fit, the more work to custom cut.

Useful to note the bigger the pieces the fewer seams and the fewer cuts. I spent significant time using fairly medium stones, and working to get them with very tight seams. Given the time spent, I wish I would have spent the money to purchase a few large and gigantic pieces to compliment the Costco pallets.

Cutting with Saw –

Most of my cuts were via an angle grinder cuts with a 7.5” Angle Grinder (Harbor Freight) and a Makita Segmented Diamond Blade. I highly recommend the Makita blade, a few other brands (dewalt, spyder), never cut well and seemed to dull immediately – the Makita blade was substantially faster and lasted for nearly my entire patio.

I did fine with the lowest budget Harbor Freight tool, but as this is the messiest and longest portion of the project, I think investing in a larger bladed and water cooled saw very possibly could have shaved weekends off the overall project. Do note the trade-off that the bigger the diameter, the more difficult it is to cut a contour or curve. Also, the dust is a mess – and if a water-cooled option reduced that mess – I can definitely see the advantage. I know Home Depot rents a concrete water-cooled saw. 

Important Note of PPE –

Sawing quartzite creates high amounts of silica dust, which is pretty nasty to inhale, so be sure to have a N95 mask with valve when you are cutting. I recommend complimenting that with safety glasses for the high velocity debris, earphones for the scream of the angle grinder, and also knee pads, gloves and steel toed boots just to complete the look.

After the puzzle was completed, the final task was now to level all the pieces. 

Its useful to note that my mindset changed over the course of this project. Every tool I threw at it was heavily damaged, at least 2 warranty claims were filed for different tools, and the project was about a year beyond my initial estimate. At this point my mindset was focused on finding and investing in the ideal tool to ease each repetitive task. With this philosophy in mind during this final stage, there were two key investments: (1) a plane laser to support the level of each individual stone and (2) a GRABO suction tool to pick up and down each stone without destroying my finger tips. 

4a. Setting up reference Laser.

My goal was to use a 2D plane laser to create a reference plane and maintain a consistent slope.

Setup Calibration Targets -

I needed to first set up some targets so that I could calibrate the laser. I took a string which originated at the patio highest point and continued to the lowest point and measure to the previous 1 in per 10 ft slope (orange dashed line in image). The precise height of the string to the ground doesn’t actually matter, just the angle, I will make a custom offset later. I then placed a second string perpendicular to the sloped string at the lowest end, and leveled that to ground (blue dashed line in image) and the two strings imperceptibly touching at the intersection. I placed a series of stakes with industrial strength reflective vinyl an inch away from the level (blue) string so the laser position could be apparent as I position the laser. 

Calibrate The Plane Laser to the Targets-

Now that the calibration targets were set up, each time I worked during the stone-leveling phase, my first step was to adjust the position and angle of the laser plane to be aligned to the target strings.

Accounting for the the Custom Offset: 

With the laser set as the ideal angle, I skimmed a ruler along the unleveled rock faces, noting where the laser plane hit. I happened to have an average slightly less than 7.5 inches. So I created a Offset Reflector Target (a 2x4 board cut to size with reflectors attached)– with the height of 7.5 inches clearly marked.  

Ideally, at the end of the leveling step, I should be able to slide the Offset Reflector Target along the stone faces and the laser always appearing at the 7.5 inch mark.

Leveling Each Stone

For each stone, I checked the level at each corner with the Offset Reflector Target, to get a sense if I needed to add or subtract sand. I picked the stone up with the GRABO tool and then added some sand in the correct corners, smoothed it with my hand, placed the stone back in place, compressed the loose sand by dropping a recycle bin full of sand on the stone face, and remeasured. Then repeated. Grab, level, compress, measure, repeat - a few hundred times. 

The laser was great for keeping the overall shape of the patio, and minimize low spots, but sliding your fingers over the seams between leveled stones was a good way to fine tune height and minimize the small bumps that might catch your foot.

Filling in the Gaps –

Dump some excess sand over the leveled patio rocks, then with a heavy-duty push broom sweep the sand over the seams to fill them up. Next slide a steel ruler between the seams to knock the sand into any deeper crevices. Add more sand, sweep and repeat. Finish by sweeping off the patio to a smooth level.

My vision of the ideal firepit is a project for another summer. The pit that in the photos is a dry-stack of the excess quartzite pieces in a 1/2 hour one evening - its a little wobbly and uneven - but is perfectly functional at roasting marshmallows and hotdogs. In the image it is about 14" high, taller than most fire rings - but about right for 3 year old's running by.

At the end of the project I am really happy with my new patio.

Unexpectedly the process itself was a very satisfying experience - especially at the stone placement stage. Similar to the massive jigsaw puzzle, there is a satisfaction in observing each clump of assembled pieces - and each missing gap between 2 stones is motivation to get just a little more done.

Still learning in the process, if there are any comments/suggestions would be interested to hear them.

In terms of resources, I grabbed a few books from the library for dry-laid stone work. A great practical resource I found at Devine Escapes website/blog, with helpful hints including the use of the GRABO tool and the aim for gaps to be between a thumb and pinky. He is a professional, and I defer to his experience and guidance. https://www.devineescapes.com/leveling-dry-laid-flagstones-how-to/