How to Build a Retaining Wall



STEP 1 – Leveling Pad Preparation

A Retaining Wall should be placed on a leveling pad of well-compacted gravel, crushed stone or coarse sand approximately 6″ thick and 24″ wide. The first course of units should be embedded below grade approximately 1/10th of the exposed wall height. Excavate to lines and grades you’ve established for your wall, allowing for the leveling pad and unit embedment. Place and compact leveling pad material. It may be helpful to add a thin layer of sand to create a uniform, level pad.

STEP 2 – Install Base Course

Place units on prepared leveling pad. As you proceed, level each unit front to back, side to side, and with adjacent units. Leveling is critical at this stage, so take your time! Align straight wall sections using a string line or by sighting down the grooves on unit tops. If your wall has a corner, begin at the corner and work out from there.

STEP 3 – Drainage, Aggregate and Backfill

First, place drainage aggregate (3/4-inch clear, free-draining, angular gravel) between and directly behind units at a minimum thickness of 12 inches. Drainage aggregate keeps water pressure from building up behind the face of the wall.

Next, place soil backfill directly behind drainage aggregate in layers no thicker than six inches. Compact the backfill, making sure it is neither too wet nor too dry. Generally, hand-operated vibratory-plate compactors can be used to achieve adequate compaction of granular soils – even on larger projects.

STEP 4 – Install Successive Courses

Stack units one course at a time. Set units back 3/4″ and insert two VERSA-TUFF pins per unit in front holes of units so they fall into the rear slots of the units beneath. Tap pins with another pin and a mallet to properly set them. Place and compact drainage aggregate behind each course as it is completed.

If your wall is higher than four feet or shoulders significant loads, you will need to install geosynthetic soil reinforcement. As each course is laid, place soil reinforcement horizontally on top of compacted backfill and wall units. Geosynthetic layers should be placed about one inch from the front of wall units. Geosynthetics are usually stronger in one direction, so follow the geosynthetic manufacturer’s directions carefully.

STEP 5 – Install Wall Caps

After completing the top course of your wall, install manufacturer’s caps, either with a slight overhang (recommended), set back or flush with the wall face.