12×12 Paver Patio on Interlocking Base Panels, Step by Step

How do you build a patio without digging out six inches of gravel? A landscape designer named Michael shows one answer on a 12 by 12 backyard patio for a homeowner named Peter: interlocking paver base panels in place of the traditional gravel base.

Planning the patio

The first step was sizing the patio so all the outdoor furniture fits with room left for walking. Because there were no large items such as a hot tub, a standard-size paving stone worked, and a 12 by 12 patio suited the homeowner's needs. Paver choices vary in size, shape and pattern. Jack on jack and running bond layouts with six by nine inch pavers are simple to install, while herringbone or pinwheel patterns require more cutting. This project uses a simple pattern of 10 by 12 inch hexagonal pavers.

Traditional base versus panels

The traditional process calls for a six inch layer of gravel paver base, then a one inch layer of sand, then pavers, finished with polymeric sand in the joints. The alternative here is interlocking paver base panels, described as lightweight, needing less digging, and letting the pavers sit right on top.

Layout and excavation

The layout is marked with string and wood stakes. It is square when the diagonals are equal, and the strings should be level. The patio needs a slight grade so water runs off, and a four foot level helps check the slope. Total depth depends on the paver height plus the base panels; the pavers should sit at or a little above ground level. The crew digs a little beyond the strings, about three inches deep, then hand tamps the area thoroughly.

Fabric, sand and panels

Landscape fabric goes down next, extending slightly beyond the paver area to minimize weeds. Leveling sand is poured over it and screeded with PVC pipes and a 2×4 for a smooth surface. Panels start along an edge, with the side flanges overlapping for stability, and are laid in a staggered, brick-like pattern. A razor knife trims curves or long edges.

Pavers, edging and sand

The pavers go directly on the panels. Starting along the edge, a string set low to the ground keeps the first row straight, and work continues toward the middle, always leaving a gap between blocks. Border stones are measured, marked and cut with a circular saw with a concrete blade, or a wet saw as an alternative.

Edge restraints are laid directly on the panels and secured with 8 to 10 inch landscape spikes hammered through the panels. Polymeric jointing sand, which has additives that provide a better bond, is swept into the joints and settled with a hand tamper, repeating as needed. A leaf blower removes the excess to prevent hazing, and a light spray from a hose activates the polymer. Finally, the excess weed barrier is cut and the area around the patio is backfilled with the soil dug out earlier.