How to Fix Uneven Flagstone Patio (Complete Guide)

How to Fix Uneven Flagstone Patio

Relaying an uneven flagstone patio happens to be a spring job but you do not have to remove them all. If you do notice that your flagstone patio or walkway has become uneven, you do not have to remove them, you can consider leveling the stone one after the other.

Uneven flagstone is a common complaint with patios and it is not only frustrating especially if you are planning an outdoor party but it can also become slippery thereby causing injuries.

Flagstones for patio are matter rock made of sandstone and it is bound together with minerals like silica, iron ore, and calcite hence they can split at any time. Flagstones are meant to be flat which makes them perfect for walkways, patios, and wall projects.

The flagstone is a generic kind of stone which also makes it cheaper than the traditional patio. Fixing uneven flagstone happens to be a spring job but not to worry, it can be done and this article contains easy processes and tips on how to fill the gaps in the flagstone patio.

What Causes of Uneven Flagstone Patio?

Flagstone patio
Image: Houzz

If you are looking forward to fixing your flagstone the first step is to understand the causes. A flagstone patio can shift due to a number of reasons and the main cause is that it has become unbalanced.

Patio slabs are meant to be smooth, stylish, and perfect for spending the upcoming summer, but if it does shift, below are some common causes.

  • Lack of solid foundation. If the ground underneath the slabs was not leveled out before installation then it is likely to shift in no time.
  • Long exposure to bad weather especially if it is installed when there was frost in winter.
  • The flagstones can shift due to the weight of people walking on them
  • Poor quality material
  • The patio might have settled and no longer leveled.

How to Fix Uneven Flagstone Patio

Rock requires a lot of prepping and effort so ideally, it might eventually shift due to the pressure or lack of a solid foundation. To fix the uneven flagstone patio, you should first look at the way it was installed and decide if you simply have to replace a few stones or fill it with some gravel.

But if you do need to redesign the whole patio and start with new mortar, below are steps to guide you.

What You Will Need;

  • Trowel or flat shovel
  • Rubber mallet or sledgehammer for larger patio
  • Polymeric sand
  • Bucket of water
  • Bricks or paving stone
  • Level mason
  • Sand and concrete mix
  • Mortar mix.

Step 1: Clean Your Flagstones

The first step will be to find the underlying cause but that has been discussed earlier hence cleaning your flagstones is the first step. You have to start fixing your flagstone patio by cleaning the old mortar.

Wash down each stone thoroughly so you can be aware of any further cracks and this process requires digging up your patio using a hammer and chisel in case of a full renovation.

Be sure not to damage any of the patio slabs while removing them to wash. In addition, use a mild soap and take extra care during this process.

Step 2: Level Out The Compact Base

The next step is to level out your patio base. Some patios might be designed with a mortar base while some are simply laid on sand or compacted dirt. To make sure you can easily lay the flagstones back when you are done then you have to install a concrete base.

The base needs to be fully compacted so it won’t become unbalanced again in no time. So, fix and compact the base to prevent uneven slabs.

Step 3: Mix Mortar

If you are using a premixed mortar then you just have to mix it with water but if you have a specific type of mortar then follow the mixing instruction on the label. Mix as much mortar as the stones you have to fix and how big. Use polymeric sand if you need a small amount and spray it across the area.

Step 4: Replace The Slabs

Replacing the uneven slab is the final step but also the most important. Consider using a vibrating plate compactor to flatten the surface and level the stones out if they seem too high. Then you can lay the stones one after the other onto the mortar.

Tape the flagstones into position carefully and to help seal it in properly and create a strong finish, the joints should be filled with a mix of dry mortar.

Frequently Asked Questions

How do you smooth the flagstone patio?

If your flagstone patio is quite high, you can try smooth it by planting ground-covering vegetation like moss or creeping thyme between the stones. Leveling the stone can also be accomplished by using some loose gravel, try to get stones that are even and smooth just like the surface.

Can you sand down the flagstone?

Flagstone patios are popular for their unique design so you do not want to use sand between the joints as it will wash away. Flagstones are large flat stones so you can use sand or mortar as the joint filler but you have to make sure the base is coarse sand and not fine sand.

Can flagstone be restored?

Flagstones are popular due to their natural vibrant look however they can start to wear out with time. Luckily it can be restored by applying a cream or powder abrasive. The process of restoring flagstone is similar to wet sanding but if there is any extensive damage, the restorer might use a floor or hand machine.

Wrapping Up

To stop your flagstone patio from disappointing you, the alternative solution will be to use a resin-bound patio surface rather than the paving spectrum of slabs.

Resin materials are high quality, installed with precision, and crack resistant, you do not have to worry about uneven surfaces either.

Lastly, remember to stay off the repaired flagstone for a few days to enable it to set and prevent cracks.

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