Interlocking stone is a paving technique in which a surface is covered with small blocks that have bevelled edges and are cut to grip each other with the aid of sand. Laid in patterns that also help the stones grip each other, interlocking stone is a flexible and attractive way of paving a driveway, patio or walkway. Although not a small job, it is possible to install your own interlocking stone. You will need time, preparation, and the proper tools, but should be able to match the look of a professional job.
Preparing Your Site
Lay out the boundaries of the area to be paved and mark them with string or spray paint.
Excavate the area marked. Your hole should be about 10 inches deep.
Set your grades. Interlocking patios need a little bit of slope for water to drain from them. They should slope away from the house to avoid flooding. A slope of 1 degree, or 1 inch of height lost for every 8 feet of patio length, is sufficient. To establish this slope, hammer in stakes at the side closest to the house and mark on them the height of the finished surface. Tie strings to the stakes at this height, and run the strings to stakes in the far corners. Using a bubble level with degree markings, check that your slope is around 1 degree.
Calculate your area. Measure the length and width and multiply the two, adding a 5% extra for wastage, or 10% extra if you are planning many curves or a border course of stones.
Buy your stones. There are many types of tumbled-stone and concrete pavers available, in many colors and patterns. Make sure that your chosen stones are delivered with laying instructions, as some patterns can be complex.
Preparing the Base
Fill the hole with gravel. To find out how high to build up your gravel, measure the thickness of your paver stones and add 1 inch (for a sand layer). This is how far below the strings marking final height your gravel will need to come. For example, if your stones are 3 inches thick, and the hole is 10 inches deep, you will need to add 6 inches of gravel. While adding gravel, run a gasoline-powered plate packer across it after laying every 3 inches of thickness. This will compress and strengthen your base.
Build a 1-inch thick layer of coarse sand for your bricks to sit on. To ensure that your sand layer has a proper slope, run a grid of strings across your site at brick height, then lay down 1-inch-thick metal bars. Slide a spare brick down the bars to make sure that they are at all points exactly one brick thickness away from the strings. When you have properly set the bars, add an inch of sand around them.
Screed your sand. To do this, drag a long, flat 2-by-8 across the bars that mark your sand height. This will flatten the sand. Remove any excess sand and use some of it to fill the gaps that are created as the bars are removed.
Pull down your strings and stakes to allow access to the area for paving.
Laying Your Stones
Lay your pavers in your chosen pattern. Start from a corner to create an area that you can stand on without disturbing the sand layer. When you place your stones, drop them in place. Don't set one edge down first, as this will push sand up between the stones and prevent a tight fit.
Cut your stones where necessary. If you are making a straight border, lay a bit beyond it and mark a straight line across your stones with a chalk line. You may then pull them up individually and cut them. If making curves, just mark them using chalk or a saw blade. Clearly mark what part of the stone is to be discarded, then cut them using a stone saw with a diamond blade. Safety goggles and a dust mask are absolutely critical, as this creates large amounts of dangerous stone dust.
Lay your cut stones to complete your pattern.
Pack the pavers down. Once all of them have been laid, spread a thin layer of polymeric sweeping sand across them to prevent chipping and run your plate packer across them, not coming closer than 8 inches from the edge, especially if there is no concrete or snap edging to hold the edges in. Pack the edges more carefully by stomping or with a hand tamper.
Add more sweeping sand. Pour out polymeric sweeping sand out into small piles, a quarter bag at a time, and use a stiff broom to sweep it into all the cracks between pavers.
Pound the pavers a final time using the plate compactor.
Sweep all excess sand off the surfaces of the pavers. Be very thorough, as once this sand sets, it cannot easily be removed.
Spray a fine mist of water onto the interlock. This will activate the polymeric sweeping sand, which will set hard and lock your stones in place. Your interlocking stone project is now complete.