When someone calls us about a patio that's sinking in one corner or has pavers that rock underfoot, the pavers are almost never the problem. The base is. And because the base is invisible once the job is done, it's the easiest place for a crew in a hurry to save a day of labor at your expense.
A paver patio built to last in Maryland starts with excavation — typically 7 to 9 inches of soil removed for a patio, more for a driveway. Skipping depth here is the single most common shortcut. If the base is too thin, freeze-thaw movement has somewhere to go, and it will find it.
Next comes the aggregate base, and the important word is 'lifts.' Crushed stone should go in a few inches at a time and be compacted with a plate compactor between each layer. Dumping the full depth and running the compactor over the top once leaves the lower portion loose. It looks identical on day one and shows itself by year two.
On top of the compacted base goes about an inch of bedding sand, screeded flat and left undisturbed. Pavers are set on it, cut in at the edges, and then locked in place with edge restraint — a rigid border spiked into the base. Without edge restraint the perimeter pavers migrate outward, joints open up, and the whole field loosens from the outside in.
The last step is polymeric sand swept into the joints and lightly compacted, then activated with water. It hardens to resist weeds and stops the joint sand from washing out in a storm. Ordinary sand in the joints is another shortcut that shows up as weeds the following spring.
Drainage ties it all together. A patio should be pitched slightly away from the house — roughly an eighth of an inch per foot — so water sheets off rather than pooling and working into the base. Combined with proper compaction, that pitch is most of the reason a patio still sits flat after fifteen winters.
If your existing patio is settling, or you're planning a new one and want it done properly the first time, call Artstrom LLC at (631) 639-1617 for a free on-site assessment.