Interlocking near you

All three can make a good driveway, patio or walkway. They differ in how they look, how they behave when the ground moves, and what a repair looks like years later.

An interlock contractor spends more time below grade than on the pavers themselves. The quote should describe the excavation, the type and thickness of the granular base, how it will be compacted, the edge restraint and the joint material, because none of that can be checked once the pavers are down.

The finished surface has to slope gently away from the foundation toward somewhere water can go, such as a lawn, a swale or a drain. If the lot already sends water toward the house, correct the grading before paving; the drainage page covers grading, downspouts and drains.

Paved surfaces send rain and meltwater into sewers and toward neighbouring lots, so many municipalities limit how much of a front yard can be paved, require a permit to widen a driveway or change a curb cut, and expect runoff to stay off the neighbours' property. Some encourage features that keep water on the lot. The rules vary from city to city, so check with yours before the design is final, especially for a new or wider driveway.

Permeable pavers have wider joints filled with small, clean stone instead of sand, over a deeper open-graded stone base that holds water and lets it soak into the ground. They can reduce runoff and puddles, but they need soil that drains, a design matched to the site, and occasional cleaning so fine debris doesn't clog the joints. On heavy clay or right beside a foundation, an underdrain or another approach may be needed.

A well-built interlock surface handles frost because the granular base drains and the joints let units shift slightly without cracking. Winter damage usually comes from water trapped in the base, from de-icing products and from snow-clearing equipment.

Because interlock is made of separate units, most defects can be fixed without starting over. The repair has to deal with the cause, though: relaying pavers on the same wet or poorly compacted base only postpones the next dip.

Polymeric sand is joint sand blended with a binder that hardens after it is swept in and misted with water. Once set, it resists washout, weeds and ants better than plain sand, but it is unforgiving: it must go onto dry pavers, be swept completely off the surface before wetting, and get dry weather to cure, or it can leave a hazy film. Joints that crumble or empty out over the years can be cleaned out and refilled.

Sealing is optional. A sealer can deepen colour, make stains easier to clean and help hold joint sand in place, but the wrong product can leave the surface slippery or cloudy, and every sealer has to be renewed. Ask whether the paver manufacturer recommends sealing, let any efflorescence clear first, and choose a product made for outdoor pavers exposed to freeze–thaw.