Tuesday, November 18, 2014

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

 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.


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.


Place filter fabric in trench and up the cut slope. Fill trench with clean, graded aggregate and compact.


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.


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.


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).


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.