Sometimes, despite using the right materials and techniques, a DIY project might not age as well as one would hope. When one couple’s pandemic patio started rocking and wobbling, they called the team at Ask This Old House for help. Mason Mark McCullough knew exactly what the issue was and set to work with the help of the homeowners. The three removed the old patio, raised the base layer, and rebuilt the perfect patio.
How to Fix an Uneven Paver Patio
Once you realize the issue is a pitch problem, the best thing to do is remove the existing patio and build the base back up to the correct grade. The following are the steps to follow to fix an uneven patio.
- Start by taking a picture of the existing patio layout to provide a guide for reinstalling the blocks.
- Remove the existing patio blocks. It’s usually easiest to slip a pickaxe under a wobbly or uneven block and pry it up. Be careful not to damage the blocks in the process. Separate the blocks into different piles based on their size.
- Remove the sand layer. It will often mix with dirt and hold too much water so it’s better to discard it than to try to reuse it.
- Install a new layer of gravel a few inches deep. If the patio needs to be built up higher, consider adding a few more inches. Wet the gravel and compact it with a plate compactor.
- Identify the corner or edge of the patio where water should shed off the surface. Install stakes in the ground around the patio and run mason’s string around the stakes. The string should be pitched ¼ inch for every foot. Over 8 feet, it should be pitched 2 inches from front to back.
- Install the new sand base and compact it into the base with the plate compactor. Install screed rods at the correct depths (relative to the string lines) and work the screed across the rods, filling in the low spots and removing the high spots as you go. Once grade is established, compact the sand again.
- With the base’s pitch established, check the string lines to ensure they’re square. Use the 3-4-5 method: Measure 3 feet in one direction and mark the string, 4 feet in the other direction and mark the string, and then between the marks. If the string lines are square, the measurement between the marks will be 5 feet. Adjust the stakes and strings as necessary.
- Reinstall the patio blocks using the picture taken in step one as a guide. Place them on the sand and tap them with the mallet to set them in place.
- With the patio blocks reinstalled, sweep polymeric sand into the joints between the blocks to help lock them in place and water the patio.
Resources
Start by using a pickaxe to pick up the pavers and stack them by size. When reusing pavers, Mark recommends snapping a photo of the patio to use as a pattern reference for later. Using shovels and rakes remove the sand or material under the pavers and set aside on tarps to be tossed or reused. Once the sand is removed add gravel to reestablish the base and compact with a hand tamper or motorized compactor. Hose down the layer of gravel and compact again.
To establish the height of the patio using stakes and landscaping string create a line around the perimeter of the patio. Set the height of the line by measuring the height of the paver. Set two metal railings running parallel on the perimeter edge of the patio base. Then cover the gravel with polymeric sand and compact it. Using a long metal or wood post, screed from one end of the patio to the other, creating a smooth level surface. After relaying the pavers spread a layer of sand to fill the gaps in between the pavers.
Use a broom to evenly distribute the sand.
