Excavating the Site and Building the Base

This part of the project is the key to a successful (and long lasting) patio. Use the bottom of a door or a set of stairs abutting the patio area as the starting point for establishing the final height and slope of your patio. Your entire slab should slope away from the house at a rate of 1 in. per 4 to 8 ft. This slope may be one long decline or a slight dome shape so water runs off in more than one direction. Place one end of a long 2x4 at the bottom of the stairway or an inch below the door threshold, then level across to stakes driven at the perimeter of the patio and make a mark.

Make another mark the appropriate distance down the stake to indicate the slope. In our case, after making a level mark on our stake with a level and 12 ft. 2x4, we made another mark 2 in. down to indicate a slope of 2 in. for that 12 ft. (1 in. for every 6 ft.)

Make a grid work of stakes and guide strings to indicate the finished height and slope of your patio, then excavate 7 1/2 in. below these lines. This will provide enough room for a 4-in. subbase, the 1 in. sand base, and the 2 1/2 in pavers themselves. If the area is hilly, you'll need to go back and forth between excavating, leveling and setting strings to get things right.

Soil conditions vary greatly across the country. After digging, you'll find pockets of loose dirt or black soil, remove it or it will eventually settle, creating a wavy patio.

Next, bring in the subbase material. It should be 4 in. deep in all places. The subbase should extend 8 in. beyond the actual edge of the patio to provide room for the edging. Compact the class 2 using a flat-plate vibrator (also known as a compactor). Go over the entire area twice.

The Essential Edging

Edging is an absolute must for maintaining the integrity of your patio. Without solid edging, your sand base and pavers will separate and drift apart as rain, frost and foot traffic pound away.

You can use Snap-Edge plastic edging. Left uncut, it remains straight and rigid, but when it's cut it can be bent to form curves. Secure the edging into the compacted sub-base with 10-in. spikes.

You can use landscape timbers for combination edging/steps in a sloped area of the yard. Crisscross corners and use double timbers on the front of steps (even though the lower one will be buried). This lower timber prevents the subbase and sand from washing out. The tops of the timbers should be at the same height at the surface of the finished patio.

Spreading Sand

Sand provides the final base for your pavers. If this surface is uneven, the pavers on top will be, too. Ideally, the sand should be 1 in. thick. What you want is a firm, flat surface for laying pavers. The sand also locks the pavers into place. When you vibrate the pavers, they'll bed slightly into the sand. If your patio is under 10 ft. wide, use a screed board with a 2 in. notch on the ends to ride along the edging to level the sand.

On larger expanses, level long lengths of iron pipe in the sand 2 in. below your guide strings, then run your screed along the top of the pipes. (when you are done with the pipe, remove it, then fill in the groove it leaves with sand). In many cases you'll use a combination - a notched screed board riding along the edging on one end and on the pipe on the other.

Whichever method you use, roughly dump and level the sand over the subbase, then fill in low spaces and rake away excess sand as you drag your 2x4. Shuffle the screed lightly from side to side as you work. You're not compacting the sand, just creating a firm solid bed.

Screed only as much sand as you can cover with pavers in one day. Prepared sand left any longer is likley to be ruffled by wind, rain, kids or a stray cat thinking he's found the worlds biggest litter box.

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