Building a Flagstone Patio in One Day

Cheers to Pete for producing the perfect flagstone patio. He’s tired.

I can’t take any credit for our latest patio project; the guy’s a flagstone rockstar, single-handedly bettering our backyard and making an outrageously cool, functional, and livable space.

We spent all day Sunday relaxing, which, to us, implies doing anything but staring/working at computer screens. That’s how Pete found himself building a small flagstone patio by himself in one day, while I sanded and stained the kitchen cabinetry.

Side note: Hi to my neon pink sneaks from 2005. I still have those kids 18+ years later.

Flagstone installation is like DIY Crossfit with natural material weights (think: buckets of sand and 200 lb. rocks). We gave you guys a heads up that this was going to be happening in the near future, but two patios in one month in 1/10-acre lot must be some kind of Guinness World Record. I don’t know, I’ve been too busy staining to give them a call.

Step 1: Make a Plan for Your Flagstone Patio

Our new flagstone patio would form a wide path between the deck and the garage gate. Measuring your square footage goes a lot easier once the children and dog are distracted.

Step 2: Cut Away the Grass For Your Flagstone Patio

Grass and weeds, be gone! Depending on the type of crusher run, sand layer, and the thickness of your stones, you may need to excavate out a few extra inches of soil to make room. We wanted the stones to be flush with the remaining grass.

Step 3: Create a Base For the Stone Patio

Crusher run tamped and topped with an inch of sand is truly ideal if you have the resources, but in this case, we just had some leftover sand from the previously built patio. We hoped that the weight of the stones was enough to anchor each one in place. If you were building a patio with smaller pavers, a sand layer alone will not be enough to prevent waving and shifting over time.

Make sure your sand is graded away from any foundation walls.

Step 4: Lay Flagstones in Place

Laying a simple patio in a day might be easier if you’re working with premade pavers guaranteed to fit together without question, but irregular natural flagstones are more challenging. As you’re puzzling your pieces together, always start by placing the stones that you know will get the most foot traffic. Work to ensure that they are properly spaced, even, level, and your top stone picks.

As you fill in the rest of the stones, you’ll have to use a sledgehammer or a cut-off machine to get your stones to the sizes you need. (I use a STIHL TSA 230 in this post published years later, which is, incidentally, also about cutting flagstone.)

Step 5: Add Sand to the Cracks of the Flagstone Patio

You’ll notice in the next picture that at some point while positioning stones, Pete went rogue and cut away more grass to introduce a soft curve to the patio design. Once the stones are puzzled and level, sloping just enough to guarantee water runoff, use a broom to fill sand into the cracks. Polymeric sand is great, but as a warning, in wider gaps like these, it is sure to crack over time. While it definitely does help cut down on weeds that grow between the cracks, in many of our various flagstone installations it has crumbled rapidly as stones shift and settle.

A couple of notes on this construction:

• We did not use crusher run beneath this patio. Rationale: We’ve both lived with patios and pathways created using only sand underlayment that do not flex/bend/break/warp dramatically, and are optimistic that this one will be a-OK too. The stones are a lot heavier than simple bricks and pavers, after all. While we had a lot of extra sand, we were fresh out of the crusher. And even though we know it’s not “the way” to do it right, we wanted to save ourselves $50 in stone and $50 in delivery charges and see how this worked. Live and learn and sometimes experiment to save money.
• There’s no polymeric sand either. We used normal sand in the cracks. We may just wait and see how the stones flex/bend/break/warp after a season of freezing and thawing. We also kind of like the idea of having grass or moss between the stones in this part of the yard, but mostly didn’t want to put polymeric between stones that were likely to shift a little bit over time.
• Its curved edge was a nice finishing touch, rather than making the new patio a rigid square/rectangle. The shape actually now mirrors nicely with our round patio.
• We still have a LOT of stones left over. More to come on how we’re going to use those babies. When you order flagstones, be prepared to use them forever.

Honestly, what an awesome backyard transformation this whole flagstone undertaking has been.