Certainly the most invasive step in the installation process, the demolition is demolition. Depending on the access of the project area, we will either demolish the existing concrete / asphalt using a skid-steer bobcat, or, using jackhammers with an air compressor for those difficult access projects. The concrete is broken up and exported to a material recycling yard where the old concrete is crushed up and used to make recycled class II road base. The average excavation depth for a driveway is 8 to 9 inches below the finish grade, however, areas with a high clay content may need to be excavated deeper to allow for a thicker road base layer.
Once the demolition and excavation are completed we will address any underground needs (drainage installation, future conduit pipes, repairing broken irrigation lines, etc..), then we will begin importing the sub-base material. We use class II road base for driveways which is the same base that Cal-Trans uses under all of the roadways. It is a mixture of fine sands and aggregates and goes up to 3/4″ crushed rock. This base is proven to provide the best compaction rate and solid sub-base structure for driveway pavers. The road base layer is typically 4″ thick (unless you are in a high clay area – then it is typically 6″ thick). The road base is graded for proper surface drainage / run-off and compacted using a vibratory plate compactor.
The bedding sand layer is a critical step in the installation process. Not only is it the leveling pad which ensures the pavers’ surface is flush with adjacent stones but it also assists in the interlocking process that gives pavers a stable but flexible system to prevent cracking. Using too thick of a sand layer will result sinking or dips in the pavers overtime. Sand does not have a high enough compaction rate to provide structural support for driveway pavers. We use 1/2″ steel “screeding pipes” that are laid over the compacted road base. The bedding sand is spread over the steel pipes and screeded using a staight 2 x 4 to provide a smooth, 1/2″ layer of sand over the road base.
Before installing any pavers, chalk lines are snapped over the bedding sand layer to represent our square line off of the house. The square angle is typically taken off of the garage slab and lines up the paver pattern with the garage to act as a pattern guide. These chalk lines preventing the pattern from curving or creeping as the pattern is extended outwards. The pavers are installed starting at one point (usually the garage) and worked outwards until the pattern overruns the border line – this is referred to as the field. We install the field pavers past the starting point of the border to achieve a full pattern. The inside border line is marked on the field stones and those stones are cut using a diamond tipped concrete saw.
Once the cutting of the field pavers is complete we will prepare for the border installation. Border stones that abut a wall or other type natural restraint do not require a concrete foundation. The border stones that do not have a natural edge restraint will need to be wet-set in concrete to lock those stones in place. For these areas we will dig a trench to match the depth of the sub-base and bedding sand (approximately 5″ deep). We then mix concrete and fill the trench, placing 3/8″ rebar horizontally in the concrete for reinforcement. The border stones are then set on top of the wet concrete and tamped in about 1/4 inch to embed the border stone in the concrete. For curve-linear border lines each border stone will need to be tapered to allow for a smooth curved border line.
The final step in the process is the joint sand installation. We use a bag dried, angular joint sand for driveway pavers because it provides the best joint lock. Other rounded sand types such as play sand are NOT recommended as they will not grip the pavers as well and are more prone to wash out. The joint sand is spread over the entire paver area at a thickness of approximately 1/2 inch. A vibratory plate compactor is then passed over the pavers several times to compact the pavers downward, sinking them into the bedding sand (about 1/8 – 1/4 inch). The vibratory function shakes the pavers allowing the angular joint sand to fall down into the joint sand bind. Another popular type of joint sand that is used as a premium option is a polymeric joint sand. This is a specialty sand that has a polymer additive that when activated after hosing down the sand, hardens and locks the joint sand into place. Alternative, many people opt to seal their pavers with a joint stabilizing sealer. This option also enhances the pavers for color enrichment.