Retaining Wall Installation

Just like with paver installation, as I talked about in my last post, we follow nationally recognized standards for retaining wall installation. With both paver and retaining wall installation there can be subtle nuances to the jobs. For example, the type of soil and slope of the earth will play a role in how installation goes and what is required. Many retaining wall projects also require a local permit and certified engineered drawings.

However, I think that is is very helpful for property owners and home owners to know what to expect so that they can make sure their retaining wall is installed properly and that their investment lasts.


We often use Nicolock pavers and this is taken directly from the Nicolock website:

Walls up to 3 feet in height (2 ft. 6 in. for Sierra) are attainable without the need for soil reinforcement (Geogrid). Recommended installation procedures should be followed to ensure the life of your wall structure.

1. Wall Cap
2. 3/4” Crushed Clean Stone
3. Top Soil
4. Existing Site Soil
5. Reinforced Soil
6. Filter Fabric (as required)
7. Geogrid (as required)
8. 3/4” Processed aggregate Footing
9. Drainage Pipe (as required)
10. Foundation Soil

IMPORTANT! Illustration shown is not for construction purpose. Please confer with your local engineer for proper placement of geogrid.

IMPORTANT! Walls higher than 36" above grade, terraced walls, weak soils and other loading conditions require special considerations in design and construction. This should be done by a qualified engineer & a professional contractor. Check with you local building department for code requirements.

The following Installing procedures apply to all Nicolock Retaining Wall Units constructed as a conventional Gravity Wall system.

PREPARING / EXCAVATING. Before beginning excavation, make sure there are no utility lines in the wall area. Excavate area to the proper depth. For geogrid-reinforced retaining walls or for more detailed information, consult your local distributor or contact Nicolock.

TRENCH EXCAVATION Excavate a trench a minimum of 6" beyond the front and back of the wall block. Dig trench 9” to 14” deep, enough to create a 6” thick leveling pad and to bury at least one whole wall block below grade. Compact the soil at the bottom of trench. Shape the slope behind wall to allow for 12” of drainage material.	TRENCH FILL Place filter fabric in trench and up the cut slope. Fill trench with clean, graded aggregate and compact.	BASE BLOCKS Position a level string line at the straight face of the unit to maintain alignment. Place the wall units side by side in the center of the prepared base. Bury the first course of block to a depth equal to 10% of the height of the wall, measured in inches. Level units from side to side, front to back.
DRAINAGE SET-UP Fill the space in front of wall with clean fill to grade to hold units from shifting. Place a perforated pipe behind wall on top of base for drainage. Fill drainage area with clean aggregate keeping filter fabric in place. Backfill soil on outer side of fabric and compact.	STACKING UNITS Place successive courses by fitting the keys and grooves onto the units in the row below (if applicable).  Keep the tops of each course clean to maintain a level surface. Stack units in a running bond pattern (crossing joints).	BACKFILL & FINISHING Continue building the wall to the desired height. Backfill with clean aggregate behind each course as completed. Backfill and compact soil. Finish the wall by securing the wall cap with a suitable masonry adhesive.

Paver Installation

One of our most popular projects is pavers-- and for good reason! Pavers often come with a a lifetime warranty, they are durable and when installed correctly can last for a very long time. When we install pavers, we follow ICPI standards and this is the process we use:

PLANNING Determine the area to be paved. Measure for square footage and sketch a diagram of the shape & pattern of paving stone desired.

PREPARING / EXCAVATING Before beginning excavation, make sure there are no utility lines within the area to be paved. Excavate area to the proper depth depending on the type of traffic. Refer to cross section diagram.

ALLOW FOR DRAINAGE  Establish the finish grade and slope or pitch of pavement to allow for drainage. Lay out the lines and corners with string line and stakes. Compact sub-base with mechanical compactor.

BASE INSTALLATION Spread aggregate base uniformly throughout the entire excavated area and 8 in. beyond perimeter lines. Base aggregate material should be processed 3/4” minus gravel or crushed concrete blend.

BASE COMPACTION Compact the base aggregate evenly throughout the area with a mechanical plate compactor. Do not compact the base aggregate in more than 4” layers. The compacted base should conform to the contour of the finished paved area. The grade of the base aggregate should be 3” to 4” below the finished paving stone surface depending on the thickness of the paver.

SAND SCREEDING Spread 1” of concrete sand evenly over the compacted base. Screed the bedding sand to a level, smooth surface using a screed board.  For areas wider than the width of the screed board, use 1” conduit pipe as screed guides 4’ apart. Screed sand, remove screed rails & fill in depressions with fresh sand. You should end up with a complete layer of smooth sand.  Do not disturb sand bed after it has been screeded.

EDGE RESTRAINTS Install edge restraints as required. Pavers butting against curbs or foundations will not need an edge restraint. Various types of edging materials can be used. Nicolock recommends a Snap Edge edge restraint system since it is easy to install and will not rot or decay.

PAVER PLACEMENT.
Begin placing paving stones on the screeded sand bed in the desired pattern. Hand place the paving stones with a hand tight joint.  Work from the paving stone side of the installation as they are set. To achieve the best mixture of colors and blends, remove pavers from delivered bundles section by section, not layer by layer, and work from several bundles at a time. Cut pieces as needed to fill in the pattern.

FINISHING.
When all pavers are placed, sweep surface clean. Spread a fine jointing sand over the entire surface and broom sweep to fill all joints.  Leaving excess sand on the paving stone surface, tamp the paving stones into the setting bed with the mechanical plate compactor with a rubber pad. Broom sweep more sand to fill any open joints.  Backfill over the top edge restraint and grade. Your installation is complete and ready for use.

Note: Concrete dust created by saw cutting pavers can stain the surface. Be sure to cut pavers away from your installation. The use of an approved safety mask is recommended when cutting any concrete products.

Source: http://www.nicolock.com/homeowner-tools/installation/paving-stone-installation