Building a Retaining Wall with Boulder Rocks

What You'll Need
Graph paper
Measuring stick
Shovel or digger
Bedding sand
Boulder rocks

If you are planning on building a retaining wall, then you will be looking at several different materials and trying to decide which is right for you. Man-made retaining wall blocks are quite popular, as they are even in size and require minimal fuss. Alternatively, people may use brick, as it is an easily sourced material. Another option is to build a retaining wall with boulder rocks.

Step 1 – Permit

Whenever you decide to get work done to your property, whether you are building a retaining wall yourself or hiring professionals, check with the authorities. If the work you want done conforms with health and safety regulations, and will not damage the aesthetics of the neighborhood, then the permit is likely to be granted.

Step 2 – Design

As with any other construction project, when building a retaining wall it is much easier to build something if you have a blueprint in front of you. While it is likely that you are not a professional at creating blueprints, a sheet of graph paper will do the job just as well. Draw a side view of the retaining wall to accurate proportions, with measurements listed. It's helpful to have a plan to view, to ensure that your wall is not going to require removing trees or any other unnecessary work.

Step 3 – Foundation

The foundation is the most important part of any structure. When building a retaining wall, the amount of wall underneath the surface should be to a 3:20 ratio with the amount of wall above the surface. You need to add 5 inches onto the foundation measurement before digging. If the job is a manageable size, then use a shovel. If not, then you may want to hire a digging machine. Once the trench has been dug, fill the first 4 inches with gravel. Compact it and level it out. Next, fill with 1 inch of bedding sand and level this. Now you can start adding the boulders.

Step 4 – The Wall

A boulder retaining wall is designed to start at the bottom with larger boulders. As the wall gets higher, the size of the boulders decreases. Although it depends on taste, the larger the boulders, the better the final finish.

No mortar is required. You simply place the boulders in the foundation, as the shape and weight of the boulders will create a sturdy wall with no additional assistance. The boulders should be arranged so that the second layer of boulders is placed in the dipped area between the boulders in the first layer, the third layer in the dipped area of the boulders in the second layer, etc.

WARNING: Make sure you put safety first and have someone help you carry the larger boulders to prevent damage to your back.

Step 5 – Drainage

While building a retaining wall with other materials requires additional drainage in the form of backfilling, drainage tracts, etc., a boulder wall has natural drainage. Although the wall is secure, there are gaps where the uneven boulders do not meet the next boulder exactly, and it is through these gaps that water will drain.

Step 6 – Finishing

In order to add the finishing touches when building a retaining wall, plug the large gaps in the wall with smaller stones or even pebbles. These will not add support to the wall, but they will make it look more pleasing to the eye.