Repair Sunken Pavers

Paving bricks are a natural choice for outdoor environments. They look good, resist the elements, are inexpensive, and last a long time. But over time they shift, sink and heave as the ground moves and erodes. That was the problem I faced with my outdoor stairs: at well over 30 years old, they had shifted and sunk to the point that they were a tripping hazard!

Fortunately, the fix is relatively easy and inexpensive! In a nutshell: pull the bricks out, level some new sand/gravel, put the bricks back.

Fixing my steps took only three hours! Your project will likely differ in length, depending on how much work there is to do.

Materials:

• Paver sand (as required)
• Polymeric sand (as required, optional but recommended)

Tools:

• Various prying implements (flat-blade screwdriver, pry bars, putty knives)
• Shovel
• Rubber mallet
• A straight 2x4 or equivalent (optional)

There is almost always an underlying cause for shifting pavers. In my case, the likely cause of the soil erosion under my paver steps is poor roof drainage. The rainwater tends to pool at the top of the steps and either runs down the steps like a waterfall, or slowly seeps through the ground under the steps.

If you can find the reason why your pavers are shifting, fix that first! Or at least fix it soon after repairing the pavers.

Using your assorted levers, start prying out the pavers. You can start from the edge or any convenient location! In the case of my stairs, I started with a loose centre brick. By jamming a screwdriver into an edge, I was able to gradually wiggle the paver upwards until enough was exposed to grab it by hand.

With one paver loose, it's easy to pull up the rest. Some came loose by hand, and others needed a little encouragement from a pry bar or screwdriver.

I placed my bricks on a scrap piece of plywood off to the side, in more or less the same pattern as they'd been removed. I also took the opportunity to clean off any dirt still clinging to the edges.

If there are any significant holes, gaps or grading issues in the base layer, now's the time to fix them! Begin by clearing out the scraps of plant matter, clumps of dirt and mud, and other junk left behind.

Most of the steps had started to sink due to erosion, leaving some fairly deep holes. I filled the holes with compacted dirt. In my case, I was able to get by with a brick and a rubber mallet! To compact larger areas you should consider renting a compactor.

One stair had actually heaved a small amount, so I ended up removing excess dirt (enough to give enough room for a good 10mm layer of sand).

At this point the base layer does not need to be perfectly level, though it should be fairly close.

Crushed stone dust or sand is used directly under the pavers because it can be levelled and compacted easily. The stone dust can be purchased in bags or in bulk.

Using a shovel, spread the stone dust in the area you're working. It only needs to be roughly level. Since my steps had existing concrete borders, I was able to use them as a reference. By filling the stone dust to a certain point, then tapping down a paver (using a mallet), it was fairly easy to find just the right amount of stone dust to raise the pavers back up to level. For most of the steps, I had to add more towards the front of the step since that is where the pavers had sunken the most.

If you're filling a large area, use a long, straight 2x4 or a bubble level to help spread and level the stone dust. You may want to get some help from a second person.

With the crushed stone underlayment in place, start replacing the pavers! This task was simple for this job - with the step borders still in place, it was easy to just put the pavers back where I pulled them from. For each "column" I tapped each paver thoroughly with a rubber mallet, to compact the sand beneath it. In some cases this caused the paver to sink lower than I wanted, so I pulled it back up and added more sand.

If you're working on a larger area, you'll want to go over the entire space using a powered vibration compactor.

This step is optional, but recommended! Polymeric sand is pretty neat stuff. When moistened with water, it hardens somewhat like concrete to keep the pavers from shifting. It also inhibits weed growth.

Pour out some polymeric sand over the pavers, and use a broom to sweep it between the cracks. If you're working in a small area, whomp the pavers with the rubber mallet to help settle the polymeric sand. For large areas, use a powered compactor.

Some cracks will fill easily, while others will need some encouragement. As you strike the pavers with the rubber mallet, you'll see some of the sand disappear. Add more sand until it no longer disappears. I find it works best to strike the edges of the pavers rather than the centres.

Set the polymeric sand by gently spraying it with water, according to the package instructions. You don't need a lot of water! There should be no standing water on top of the cracks. Ideally, this should be done on a day when there is no rain expected for at least 24 hours.

Congratulations! You're done! That wasn't so hard, was it? Hopefully your paved walkway, stairs or patio will remain rock solid for another few years.