How to Install Flagstone Patio with Mortar | Step By Step Guide

Installing a flagstone patio in your backyard or pathway can give an attractive look to your home as many people don’t like grass in their garden, so they prefer to install flagstone under patio furniture to provide an eye-catching look. Instead of using blocks on your pathway, you can install flagstone to give an impressive and attractive look. For this purpose, you must learn how to install a flagstone patio with a mortar and other substances. In this article, you will see the full procedure through which you can install flagstone by yourself without hiring anybody at work.

There are two ways from which you can install flagstone:

  • Dry set: In this type, you can install flagstone directly on the ground. This approach is cheaper and easier to work in. It’s the best type for creating a garden pathway or walkway.
  • Mortared Stone: While mortared stone is more challenging and expensive, it’s the better choice to create it on a patio surface such as large and durable.

How to Install Flagstone Patio with Mortar: Tools Required

Spade shovel

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Now I will explain to you 2 methods:

How to Install Flagstone Patio with Mortar

Method 1: Installing mortared flagstone:

Step1: Planning your patio:

  • 1st of all, you need to consider the space and shape.
  • Take a permit from your local consultant that you are not violating the law. If you build something that your government is not allowed, it will force you to remove it; otherwise, it will become problematic when you have to sell your house.
  • Make sure no gas or water pipe is running underground or near the patio.
  • By using a marking paint, mark the particular area. It will make it easier to take measurements.
  • In the mortared installation, you only have to work on the top slab.
  • As you are covering the existing slab with flagstone using this technique.

Step 2: Pressure wash:

  • If you are working on a concrete slab or laying flagstone in the sand, or laying flagstone over dirt, that pressure wash will better bond to the surface.
How to Install Flagstone Patio with Mortar

Step 3: Layout and cut your stones:

  • Start by putting the big slices of stones on the marked line.
  • It’s better to place larger stones on the edges because the smaller stones will move with time.
  • When you place the small flagstones in the center, the big flagstones will lock it together.
  • To cut the stone, you can use the diamond blade on it.
  • You must remember if you put the stone during mortar that it will become difficult for you, so it’s better to set stones and make yourself satisfied with the stone arrangement.
  • In the mortar method, keep your all slab narrow; thus, it will make a cleaner and smoother finish. 
flagstone patio mortar vs sand

Step 4: Mix your mortar:

  • Do you know what mortar is? It’s a combination of water, sand, and cement.
  • You have to use the sand and cement in a ratio of 2:1 each. If you are taking sand in 2 cups, you have to make cement in 1 cup composition.
  • Now start mixing in a container, pour water to make a consistency into the mixture, and continue pouring until it reaches the cake frosting-like consistency.
  • If you are installing flagstone 1st time, it’s better to take all small quantities.
how to install flagstone over concrete steps

Step 5: Lay your stone in an applied mortar:

  • Now start applying the mortar, then set stones one by one into the mortar. In another sense, the stones will lie over the concrete patio.
  • If your stones are not in an exact position, then apply more mortar under uneven stones to make it even. In this case, start by identifying the thickest stone, then applying more mortar, then working outward from this stone.
  • Ensure that each stone is at the same height.
  • Please don’t do anything, even don’t walk over it until it dries.
laying flagstone in sand

Step 6: Fill the empty spaces:

  • You can fill the space with joint fillers, mortar, sand or gravel, or grout.
  • If you are using grout for filling, then purchase it from any home store and follow instructions on the bag on how to mix it. Press your grout between joints and immediately pass the grout in other gaps by using float. Let it sit for 15-30 minutes. When it dries, then wipe the area with a towel to remove excess sand. If you are not satisfied with the grout color, mix some color dye into the grout to make the area colorful and attractive.
  • If you are using gravel as a filler, then pour filler in gaps and spread it with a broom; after sweeping, pour some water and let it dry by itself.
how to install flagstone over concrete steps

Step 7: Seal the joints:

  • In this step, when the mortar filling or grout filling gets dry, then apply the sealer. You can purchase it from the hardware store or paint store.
  • This filler will prevent any water from penetrating inside the joints. In this way, stones stay longer inside the joints.
  • Sand and gravel filling don’t need any sealing. 

If you tend to lay a flagstone walkway with concrete, you must follow the same process above.

laying flagstone in sand

Method 2: Installing dry-laid Flagstones:

Step 1: Planning your Patio: 

  • 1st of all, you need to consider the space and shape.
  • Take a permit from your local consultant that you are not violating the law. If you build something that your government is not allowed, it will force you to remove it; otherwise, it will become problematic when you have to sell your house.
  • Make sure no gas or water pipe is running underground or near the patio.
  • By using a marking paint, mark the particular area. It will make it easier to take measurements. 

Note: To find the total area for your patio length of area × width= total area.

Step 2: Dig:

  • As you are going to evacuate the visible area which you marked to evacuate
  • Now cut through the sod and hose along with the edge’s inner side using a spade shovel. Now you will think how much area is better to dig than approximately 3-6 inches down are enough to dig. Still, it depends on the thickness of the flagstone over the concrete you planned to lay.

Step 3: Add gravel base:

You can divide all steps into 3 part:

  • Landscape fabric
  • Gravel
  • Sand

Landscape fabric will prevent weed and other unwanted soil from penetrating your patio.

Gravel:

  • Now, put gravel base on the dug area.
  • At the gravel 2″ at a time. And press it down before adding more gravel to make it even.
  • You can press it down by using a hand tamper.
  • Make sure it leveled perfectly.
  • This technique will keep your patio flat for a long time; it will also support your stones from being cracked or broken.

Sand:

  • In the final step, pour 1″ sand over gravel.
  • Now make it smooth and even with a rake.
  • You can put water with a hose to make the sand wet. It will make it easy to secure your flagstone.

Step 4: Put together the flagstones:

  • Start by putting the big slices of stones on the marked line.
  • It’s better to place larger stones on the edges because the smaller stones will move with time.
  • When you place the small flagstones in the center, the big flagstones will lock it together.
  • To cut the stone, you can use the diamond blade on it.

Step 5: Level the stone:

  • To level each stone, start by placing the level to see how it sits on the grading.

Step 6: Fill the gaps:

  • To fill the gaps with a joint filler or pea gravel, put material inside and spread it with a broom to evenly fill the gaps.

How to Install Flagstone Patio with Mortar: FAQ

What kind of mortar do you use for flagstone?

  • Do you know what mortar is? It’s a combination of water, sand, and cement.
  • You have to use the sand and cement in a ratio of 2:1 each. If you are taking sand in 2 cups, you have to make cement in 1 cup composition.
  • Now start mixing in a container, pour water to make a consistency into the mixture, and continue pouring until it reaches the cake frosting-like consistency.
  • If you are installing flagstones 1st time, it’s better to take all small quantities.

What is the best material to put between flagstones?

In my opinion, mortar is the best material to put between flagstones as it’s a combination of sand, cement, and water. You only have to work on the top slab in the mortar installation as you cover the existing slab with flagstone using this technique.

How do you attach flagstone to a concrete patio?

You have to use the sand and cement in a ratio of 2:1 each. If you are taking sand in 2 cups, you have to make cement in 1 cup composition. Now start mixing in a container, pour water to make a consistency into the mixture, and continue pouring until it reaches the cake frosting-like consistency. Now start applying the mortar, then set stones one by one into the mortar. If your stones are not in an exact position, then apply more mortar under uneven stones to make it even. In this case, start by identifying the thickest stone, then applying more mortar, then working outward from this stone.

Conclusion

To conclude this topic, installing a flagstone patio with mortar gives you the best results and stays for many years. Flagstone patio provides an attractive and clean look under your patio furniture. I hope you enjoyed this article.

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