May 2019

Retaining Wall Installation

Retaining wall installation has to start from the bottom. Base preparation is the most vital part of the wall installation process. Begin laying out the trench with a string line. Dig a trench 6″ to 12″ deep and about 4″ wider than the width of the style of blocks you intend to use. If your property slopes, step the trench up or down, allowing for at least half the height of a block to be buried. This saves time and material. Compact the trench and fill it with 3″ to 6″ of gravel (see “Base Thickness Chart” below). Rake out, level, and compact the gravel.

Laying the First Row

Some retaining wall products must be split. Use a 3-lb. mallet and a 3″ – 4″ chisel to split blocks along the center groove. This gives each unit the natural split face appearance. If your design has a corner, start by using a corner unit. Place each unit directly on the compacted gravel base to begin the wall installation, leveling each one with a carpenter’s level. Take your time and do this properly.

Laying Additional Rows

Sweep debris off the top of the first row and place your first block, starting at a corner if you have one, offsetting it by half a block. This will ensure your joints will be staggered, which is necessary for proper stability of the wall. Cut a block in half to complete the beginning of the row. Continue in this fashion until you reach your previously determined height, backfilling every two rows.

Backfilling

Gravel is used behind the wall as backfill to allow for drainage. Be sure to backfill every two rows as you progress in height. A filter fabric material is used to separate the native soil from the gravel to ensure the gravel won’t become clogged and prevent proper drainage. Make sure you allow enough fabric to cover the final height of the wall. To ensure proper drainage behind the wall you should install a drainage pipe.

Coping

Coping units are used to finish off the top of the wall. They are glued in place with masonry adhesive. If your wall is curved you may have to cut the coping units to fit.

Steps

Step creation is similar to installing a retaining wall. The difference is, with steps you must compact the gravel behind each row (or riser). Place the first row of wall units directly on to the compacted base. Line up the area behind the row with the filter fabric, then fill with gravel and compact to the top of the blocks. Fit and glue the coping units (or treads). Place the next row of blocks directly behind the coping for your second tread and repeat these procedures for any additional steps required. One attractive option is to create a longer tread by installing pavers between the risers.

Raised Patio

To build a raised patio, follow the same procedure as for retaining walls. Backfill with gravel to within three inches of the top of the final height of the patio. This allows for a bed of screeded sand and the height of a paver.

Planters

The difference between constructing a planter and a raised patio is that you backfill and compact the gravel to within 6 inches of the top of the coping. Place a filter fabric over the gravel, then fill with topsoil for planting.

Helpful links:

Garden & Retaining Walls

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Paver Installation

Paver installation begins long before you put them on the ground. Planning and design starts with a clear idea of what you want to accomplish. A detailed, measurement inclusive sketch of the overall area is necessary to determine product quantities and project budget. This can range from a simple, drawn sketch or one completed by a landscape professional. Bring us your sketch and our installation experts can determine the quantity of materials required for your project. Then, you can move forward with the multiple steps involved in paver installation.

Base Preparation

Begin by marking out the area to be excavated. Excavating removes loose topsoil or fill and allows for the placement of a compacted gravel base. Small areas are easy to excavate by hand, but for larger areas you may wish to hire an excavating contractor. Before you excavate you will need to call local utility companies (e.g. phone, gas, and electric) to ensure that the area in which you plan to dig is free of underground cables or pipes. Technicians will come and mark these areas, usually at no charge. Always excavate the area to be paved slightly wider to give you some breathing room. Fill the area with the correct amount of gravel (see “Base Thickness Chart” below), then grade your base material as closely as possible to the final contour of the patio surface. Remember to slope all installations away from the house for drainage purposes. An attractive alternative to excavating for a patio is creating a raised patio using retaining walls.

Compacting the Gravel Base

The base preparation is the most important part of the entire installation process. Appropriate base material, thickness, and compaction are essential to ensure your installation will last a lifetime. Use either a hand tamper or plate compactor and firmly compact the gravel base material. For best compaction, compact 4″ layers.

Screeding

Pavers are laid on a bed of coarse sand. This bed should be 1″ to 1-1/2″ thick, no more, and is placed directly on top of the compacted base material. Using screed guides (1″ to 1-1/2″ in diameter) placed on the base, level the sand evenly by pulling a straight board along the guides. You can check the final level of the pavers by placing a paver on a guide. Once you’ve completed an area, remove the guides, filling the grooves, and continue screeding.

Laying

Begin placing the pavers directly on the screeded bed of sand, leaving a small space of approximately 1/8″ between each paver. Start laying along the longest straight side of the area to keep lines straight. This will minimize the amount of cutting required. It is important that the lines of your pavers are square, 90 degrees to each other, to fit properly. If you are installing circles, fans, or a soldier course (a border of pavers around the perimeter of an area) you will want to place these first before installing the rest of the pattern.

Cutting

You may need to cut pavers that don’t fit along edges or around objects. Mark the pavers and cut with either a guillotine cutter or masonry saw. A guillotine cutter is the easiest cutting method, but for an exact cut a masonry saw works best.

Edge Restraints

Edge restraints are a critical element to the durability of a paver installation, as they prevent the pavers from moving and shifting over time. There are several options for restraint, including plastic edge restraint that is economical and effective. Various concrete edging materials also work well with color and texture.

Compacting the Pavers

After the installation is complete, including edge restraints, the pavers must be swept clean and then compacted with a plate compactor. This helps settle the pavers into the bedding sand and creates a smooth, flat surface.