How To Build A Boulder Retaining Wall

Boulder retaining wall in backyard with pathway running through for walking

There are many opportunities to create a natural landscape when designing your backyard. From integrating sweeping beds of perennials to introducing a variety of tree species to your backyard palate.  If you have a sloping backyard, one of the most beautiful ways you can bring a natural feel to your property is a boulder retaining wall. Before you can start planning one, you need to know how to build a boulder retaining wall. In this article, we’ll explain what to decide upon and expect.

How To Build A Boulder Retaining Wall Visible And Hidden

Boulder retaining walls are built a few different ways. The style of boulder retaining wall that you choose will likely depend on your backyard setup and then your preferences as a homeowner. Here are a few of the boulder retaining wall projects we’ve designed.

Out Of Sight Boulder Retaining Wall

First there’s the wall you don’t see.  These are retaining walls built at the edge of the property when the yard sloping down and away from the programmed areas of the backyard. You build the boulder retaining walls out of sight. In this case, you don’t need to worry too much about boulder placement. You just need to make sure they are secure and provide the retention of earth to create your level backyard.

Visible Boulder Retaining Wall

Then there’s the yard which slopes up and away from the programmed areas. In this situation, you will be building a wall which is visible from the main programmed areas. These boulder retaining walls need to be built with care. To ensure a boulder retaining wall is ideally crafted, you must consider the planting which goes along with the boulders.  It can help to lay out where trees, shrubs, and perennial beds will go prior to building the wall.  

How to build a boulder retaining wall shown with large rocks and small plantings in backyard

How To Build A Boulder Retaining Wall

There are many things to consider when building a boulder retaining wall. Aside from the normal questions like how much a boulder retaining wall costs and who to hire to build it, there are several phases of the wall itself that are important to understand.

Integrating Plantings

Instead of stacking the boulders one on top of another, use some additional space to create the slope and give yourself plenty of space to plant the sloping earth.  This creates the illusion of the rocky planted hillside which when done correctly appears to naturally blend into the landscape like it was always there.

Boulder Placement

Boulder placement is one thing, but first your need the boulders right?  If your property is riddled with boulders, you may be able to source them all on site.  Most of the time however, you need to find a source for your boulders.  There are landscape supply shops which can help with this, but you may want to skip a step and go straight to an excavation contractor.  You can find a great contractor on home design sites such as Houzz. They often have access to less expensive sources of material and can help you source the boulders you will need.

Tagging The Boulders

If you are able, it is nice to be able to tag the boulders you plan on using in your boulder retaining wall.  Often this will be a more expensive source of boulders which allows for tagging, but it’s never a bad idea to ask.  If you have your excavation contractor building the boulder retaining wall, make sure you understand how the boulders will be placed.

Questions To Ask

Will the excavation contractor be placing the boulders with the excavator’s bucket and thumb? The alternative is using lifting straps to place each boulder?  Using straps takes a lot longer and will increase the cost of the project measurably.  Conversely, using the excavator’s bucket to build the wall will scratch up the boulders but cost quite a bit less.

What To Expect During Installation

When you have your boulders selected, and the installation method confirmed, it’s time to begin.  You ought to plan on being home during the boulder placement if you are able.  Your contractor may be bothered by this, and try your best not to get into anyone’s way.  However, you may want to get involved in the boulder setting process to make sure the wall is built as you’d like to see it built.

How to build a retaining wall guide with rock walkway and patio nearby

Pro Tips For How To Build A Boulder Retaining Wall

If you are less hands-on, you may want to hire a landscape designer or landscape architect to oversee the boulder placement process.  Though it seems random, setting boulders is an art form and can have drastically different results depending on who oversees the setting of the boulders themselves.

When you build your boulder retaining wall, remember it’s your boulder retaining wall.  You can have it built to look however you wish within reason and budget. Consider what else you have going on in your backyard and make sure your boulder retaining wall fits in.