Site Preparation Begin by staking out batterboards and stretching strings between them to establish the patio outline. Adjust the strings so they represent the outer edges of the 6x6 timbers. Check with a framing square to ensure that the strings form a perfect 90-degree angle with the house and where the strings meet at exterior corners. Use the strings as guides to dig a trench around the patio perimeter to a depth of about 8 inches (photo 1). If the ground slopes, begin excavating at the high end and keep the trench bottom level as you dig. Next, line the trench with 2 inches of crushed granite ($3 for a 50-lb. bag), sprinkle the surface with a little water and compact it with a hand tamper (photos 2 and 3). You could use sand, but crushed granite compacts tighter and forms a stronger, more stable base. Add another 2 inches of granite and tamp the surface again. (Rent a steel hand tamper, or make your own by screwing a 12-inch-long 2x6 block to the end of a 4-foot-long 4x4.) Check the trench bottom with a 4-foot level; if necessary, remove or add a little crushed granite until it's perfectly level. Next, cut the 6x6s to length with a handsaw or circular saw. A 7 1/4-inch circular saw only cuts about 2 7/16 inches deep, so you'll have to cut along all four sides and then cut through the final 1/8 inch or so with a handsaw. Use the same approach to cut half-lap joints in the 6x6 ends for corners where timbers join. Mark the 2 3/4- x 5 1/2-inch joint and cut along the lines with a circular saw (photo 4). Then use a handsaw to sever the remaining wood and free the waste piece (photo 5). Apply a generous coat of wood preservative to the fresh cut (photo 6).