Retaining Wall Installation

As in all construction you must first choose a product that is suitable for the job which you wish to accomplish "e.g. you don't want to build a 6 ft. high wall with a stone that is 2 inches in thickness (it would be preferable to build it with a 3 to 5 inch stone). A 2 inch stone would be fine to build a 3 ft wall.

After you determine the size and placement of your wall you might want to consider any obstacles that could be in your way, e.g. trees or bedrock. It is best to avoid these if they interfere with the base row of your wall. If the wall must encounter these obstacles then there are certain rules to follow.

If you encounter roots, you can cut some tree roots without causing harm to the tree. Usually you can take up to 30 % of a tree's roots without any ill effects. The one thing to remember is once you have dug for your foundation is to cut the roots clean. This means that you have to take a saw and cut them flat so that the tree can heal.

Once you have dug out the foundation to 12 inches below grade you have to add and compact layers of gravel, e.g. 0 to ¾ or "granular A". These should be added 3 inches at a time and compacted between layers. Adding water as you compact will help you achieve better compaction. Usually a trench dug 12" deep by 14" to 16" wide is perfect.

After this is done you are ready to start laying stone. The first row of stone should always be ½ buried below grade to ensure the bottom does not get pushed out from pressure behind the wall. Once the first row of stone is laid and level the rest is simply choosing stone and laying your rows evenly. With each new level of stone you add to the wall you should set that row ½ " further back than the previous row. This ensures that the wall will push against the fill behind it and add a great deal of strength.

As you build your rows you will want to add a geotextile fabric behind the wall to ensure that the fill does not wash between the stones when water is present at the top of the wall. Also you should add a perforated drainpipe at the base behind the wall before you start to backfill. This will ensure that there is no buildup of water at the base of the wall when it freezes in the fall. The excess water could push out the base of your wall when it freezes.