Interlocking pavers are made of either compressed concrete, or clay, and have a minimum strength rating of at least 8,000 psi. Pavers have been used to make roads, driveways, patios, and pedestrian walkway areas for thousands of years, dating back to the early Roman Empire. Today’s pavers are different in style, similar in process. The Romans excavated their roadways and compacted native soils using tree trunks, building up and compacting soils in several lifts until the base for their pavers was sturdy. They used large, square or octagonal shaped granite stones to pave their road ways, many of which are still intact today. The modern installation methodology is similar in nature, using a compacted base material and laying segmental interlocking units to form a flexible, yet unbelievably study surface.
The following is a step by step overview of how pavers should be installed to guarantee your driveway, walkway, patio or pool deck will last a lifetime.
Excavation – Depending on the area you live and the native soil types, you will have to excavate to a depth that will ensure a stable sub-base. For example, in southern California, specifically San Diego, we have a few different soil types. Some areas have hard, decomposed granite, and some areas have soft clay native soils. The two soil types will require different excavation depths. In the case of the decomposed granite soil an excavation depth of 7.5” in usually sufficient. In the clay areas a depth of 10.5” is preferred (or deeper depending on moisture levels).
Base preparation – Recycled Class II road base is used to give the pavers a strong foundation to lie on. Class II base is made up of ¾” minus aggregate, decomposed granite and sometimes recycled concrete materials. Whatever your total excavation depth is minus 3 & 3/8 inches (the thickness of your pavers + sand) you will fill back up with compacted base. I.e. let’s say we excavated 7.5” – Our pavers are 2 3/8” thick and a 1” thick layer of washed masonry sand will be laid over the base, so we need to leave room for 3 3/8” inches of other materials. This makes our base depth 4”. This should be spread, graded and compacted in 2” lifts.[/p]
Sand – We recommend using washed masonry sand for the bedding sand layer that is placed over the compacted base material. The 1 inch thick layer of sand is used to make a smooth level surface for the pavers to sit on and to have a bedding that the pavers will sink into (about ¼”) during the final compaction.
Installing the pavers – After the Class II base and masonry sand have been installed, you will need to find an area off the house or adjacent landmark that you will want to square up with. Most patterns will have visually long running joint lines. You will either go square off of this, or, you will run at an angle (a 45 degree angle is popular). Once the line is determined, you will run string lines along that path to ensure your stones are going in square and straight, and not drifting as you move farther away from your starting point. It’s painful to stand back after laying 1,000 square feet of pavers to see your running lines veering to one side or another.
Cutting and installing border stones – Once your field pavers have been installed all the way out past the starting line of your border stones, it is time to trace out your border line and mark any field stones that will need to be cut. Most installers will use multiple ½” pvc pipes joined together to bend and turn into the radius they wish to achieve. If you will have a long straight line you can simply snap it with a chalk line and move on. After all of the field pavers have been marked for cutting, it is time to do just that. Using a wet table saw (powered by a 220v outlet) with a diamond tip concrete saw blade is recommended. They are cleaner (minimal dust) and produce a fine, consistent cut. After cutting your field stones, you will make any necessary cuts to any border stones to achieve a smooth and soft curve with your border.
Concrete Bond Beam – Excavate from the starting point of the border to the end of the border stone, and down to the native soil. It is important that you excavate down the entire depth of the sub-base makeup. This is where you will be mixing and pouring concrete to use as your border stone anchor. Your concrete should go from the bottom of the road base (adjacent to the field stone) to the top of the masonry sand. Your border stone will be placed on this wet concrete and tapped down until it is flush with the field pavers. The concrete acts as a retaining wall for the sub-base material and prevents any undermining of the concrete bond beam later on, and bonds to the border stone anchoring it down so there is no shifting. Be sure to place two pieces of 3/8” rebar into the center of your concrete bond beam for dimensional stability.
Joint sand and final compaction – The final step in completing the installation of pavers is to spread an inch to 1.5 inch layer of a fine, angular joint sand over the pavers using a push broom. Using a vibratory plate compactor, make several passes over all paved areas. This will vibrate the stones allowing the joint sand to fall and get compacted into the pavers joints. Also, this final compaction is used to set the pavers into the 1 inch layer of bedding sand.
After the above steps are completed you may clean off any excess sand or dust and the patio is ready for immediate use. You may chose to use a pavestone sealer to lock the joint sand into place or to give your pavers a “wet look” finish that will enhance and bring out the colors blended into the pavestones.