Hard Landscape Training

Brick Paver Patios and Driveways

• In many parts of the United States sand is used as the base for patios because it compacts well and is easy to work with. However, sand moves significantly with the soil and attracts ants, creating a pest problem over time. The best base material that can be used for patios and driveways is traffic bond, which is a very fine gravel material. When this material is wetted and compacted, it becomes hard like concrete and does not shift nearly as much as sand. The base should be a minimum of 4 inches deep for patios and 6 inches for driveways.

  Patio and driveway paver bricks tend to be 2 3/8 inches thick and vary in size from 4-by-8 inches to 12-by-12 inches. There are pavers available that are thinner, but they are of poor quality and are not used by professional installers.

  The best process to prepare a patio base is to dig out the area 6 inches down, dump the traffic bond into the area, and spread the traffic bond out evenly. The entire area should be lightly watered with a garden hose and compacted with a plate compactor. A rotary laser surveyor is then used to establish the height for correct drainage and pitch of the patio. The laser is also used to set a perimeter string line that shows the top of paver height.

  Screeting is the process of making the traffic bond base perfectly flat so that the paver bricks can be laid quickly and accurately. A straight board made of high density wood or aluminum is dragged across the surface of the traffic bond using stakes on either side to ride the string lines and establish the finished height of the traffic bond that the pavers can be laid on. No more than a 1/4 inch of traffic bond can be loose while screeting, so this process is the most time consuming part of laying the paver patio or driveway. Once complete though, laying the pavers is very easy.

  Pavers can be laid in multiple patterns. The most popular is called a running bond which has the pavers running in a straight line. This is the easiest to lay, but must be monitored constantly to make sure that the lines are running straight.

  Herring bone is a pattern where the paver bricks form an "L" shape and is considered to be a more formal brick pattern.

  A basket weave pattern has two blocks running horizontal stacked with a brick on each side perpendicular to the two middle pavers, like a sandwich.

  Random pattern pavers are pavers of the same type but different sizes and have a specific pattern that they have to be laid in, but look random. These pavers are usually tumbled, meaning the pavers have been manufactured to look weathered and beat up.

  Flint sand or polymeric sand is used in between the brick pavers to keep them from shiftingb along with plastic edging that is staked into the ground. The sand is swept into the cracks with a push broom and lightly washed down with a hose.

  Polymeric sand is a mixture of Portland cement and sand that drys hard, but keeps some flexibility for expansion and contraction. This type of sand needs to be fully washed from the surface of the patio before it cures so it will not harden.

  All pavers should be cut with a concrete saw and respiratory, eye, and ear protection should be worn at all times when cutting or around a co-worker cutting pavers.

Flagstone Patios And Walkways

• Flagstone is a natural material that has many colors and shades. Because it is natural, it's thickness from edge to edge is different throughout making it much more difficult than pavers to work with. The key to laying a nice flagstone patio is to have a flexible, yet solid base. For this reason, sand is the best base for flagstone. A 4- to 6-inch base of sand should be compacted with a plate compactor. Then rake the surface lightly with a stone rake to break the surface tension and allow the stones to be shifted back and forth.

  When setting the stones, the edges should be as tight as possible, but will be impossible to make perfect. A brick set (stone chisel) is the only instrument that should be used to manufacture an edge of stone, as cutting the stone will stick out like a sore thumb. The stones need to be solid, so using the butt end of a rubber mallet to pound sand underneath the edges of the stone will support the entire stone. Stand on each stone individually as it is laid and check to make sure that you have some consistent pitch for proper drainage.

  There is no wrong pattern with natural stone, it just needs to be as tight as possible for patio purposes. Once the patio is completely laid, polymeric sand is used to fill in the cracks between the stones. The sand is wetted down and the result is a solid surface flagstone patio.

  Flagstone walkways are very simple to install. A garden tiller is used to churn up the soil and leave the soil nice and loose. The flagstone will be laid directly in the soil, so this leaves plenty of room to lay the stones in. Walkway flagstones should be very large, at least 3 feet wide, as you want solid pieces to prevent trip hazards. The pieces can be spaced 2-4 inches apart as you will want to plant grass seed in between the flagstone pieces so mud does not form on the surface of the stones.

  The flagstone is stabilized by jamming dirt around the edges with the butt end of a rubber mallet. The rubber mallet is used for adjustment of the stone if necessary.

  Dirt must be filled in around the cracks between the flagstone pieces, seeded with grass seed, and covered with straw. The area should be watered at least twice a day for 4 to 6 weeks to get sufficient grass to grow. In shaded areas where the grass does not grow well, moss can be planted or bark mulch can be laid between the cracks.

Boulder Retaining Walls

• Boulder retaining walls are constructed of large, round rocks between 12 inches and 24 inches on average. The larger rocks are used for the base and are set in place using a skid loader. After the base course is set in place, the base has to be back-filled. If there is no patio or driveway that the boulder wall will be supporting, back-filling with dirt and compacting it with a plate compactor is fine. However, if there is a patio or driveway the boulder wall is supporting, then it will have to have perforated drain tile laid behind the wall and exited around the wall. The back-fill will have to be a slurry (mix of concrete and gravel) to keep the area between the boulders from washing out and supporting the extra weight. Geo-grid should be used, in either case, every 4 feet of height the wall goes up. This will act as an anchor for the wall and keep it from tipping forward.

  It is important to place each course of boulders in between the last course of boulders laid so they fit together as well as possible. This keeps the boulders from slipping and falling out.

  Most boulder walls are constructed from granite, but really any large, round rocks can be used to construct boulder walls.

  There are large, flat rocks called out-croppings that are used as retaining walls also. These rocks are much easier to work with and do not require Geo-grid or slurry mixes to maintain it's retaining abilities. These rocks are very heavy and are typically installed with a high hoe or large skid loader. They are back filled with dirt or crusher run (large gravel) when a driveway or patio is being installed on top of the wall.

Manufactured Retaining Walls

• Manufactured retaining wall block is one of the easiest materials to work with because it is consistent throughout the block. The best method of installing a manufactured retaining wall is to lay down a 6-inch base of traffic bond, compact it, and screet it so that it is perfectly level. The bottom course should be buried below grade to anchor the wall and keep it from slipping out from the bottom.

  The blocks interlock and form cavities that clear gravel can be poured down to give the wall more strength. The area 24 inches behind the block should also be clear gravel and compacted. Any wall over 36 inches high should have Geo-grid locking the block down so that the top will not tip out.

  The soil and the stone back-fill should be seperated by filter fabric, allowing the water to pass through the soil and rock but keeping the soil and rock separate.

  Caps can be cut and glued to the top of the walls with PL400 adhesive, commonly used for gluing down subfloor.

  Manufactured block is made of molded concrete and can be cut with a concrete saw.

  Retaining wall blocks typically come in 6- and 8-inch block heights and range from 35 to 55 pounds per block.

Hillside Stairways

• Hillside stairs are common on properties that are on a lake and have limited access to the shoreline. In order to properly install a hillside stair case, it is important to determine where the landing is going to be at the bottom. Once this is determined, the excavation can start for the bottom step.

  The steps are made of large pieces of flagstone that are 6 to 8 inches tall and weigh roughly 300 to 400 pounds each.

  Each step should have a 6-inch base of 3/4 crushed gravel underneath it that is compacted with a hand tamper. Each step will have to be pitched slightly toward the front to allow water to run off properly, as well as the step being level from side to side.

  Set the step in place with a high hoe or mini excavator. Manually move the step into the final position, back-fill behind the step, compact the crushed gravel, and set the next step. Continue until the stairway is complete.

  Each step has to have a minimum tread of 10 1/2 inches unless winding, then one side can have a minimum of 9 inches.

  Because the stairway is being cut into a hillside, there usually needs to be a small retaining wall built to keep the soil from washing onto the stairway. The retaining wall should be back-filled with clear gravel and the soil and gravel should be separated by filter fabric.

Fire Pits

• Fire pits that are built into a landscape have to be, by code, a minimum of 25 feet from the house or other combustibles. It may not be below power lines and all trees should be a minimum of 15 feet from the fire pit. The pit itself should be between 36 and 48 inches with the bottom lined with stones or larger rock. The sides can be any non-combustible material.

  Fireplace grates should sit a maximum of 6 inches from the bottom of the fire pit and be constructed of metal or stone or any other non-combustable material.

Gabion Retaining Walls

• Gabion retaining walls are constructed of large metal baskets that are filled with stones or rocks greater than 3 inches in diameter, and stacked to retain earth.

  The area is prepared by digging down 24 inches and back at least 24 inches, laying filter fabric down on the dug-out section and dumping 12 inches of clear gravel down. The gravel is then leveled off and compacted. The baskets are placed on the gravel and filled with large decorative, stone or rocks that give the baskets weight and have a modern but rustic twist on retaining walls. Once the baskets are filled, there are back-filled with clear gravel and the next layer of baskets is stacked on top of them and filled.

  This type of retaining wall is not common, but very effective and easy to maintain as drainage is never an issue taking hydrostatic pressure out of any equation for retainability due to the massive weigh of the gabion baskets (500 to 2,000 pounds per basket when filled).

  These walls are constructed with skid loaders as very little hand work is needed besides the original prep work.