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How to Build a Rock Retaining Wall for your Brisbane Home
- What is a Retaining Wall
- Common Types of Rock Retaining Walls
- Dry Stack Stone vs. Mortared Rock Retaining Walls
- Essential Tools and Materials Needed
- Step-by-step Process of Building a Rock Retaining Wall
- Cost of Building a Rock Retaining Wall in Brisbane
- Top Retaining Wall Builders in Brisbane
- Benefits of Having Rock Retaining Walls
Having a rock retaining wall is one way to add value to your home, especially if your yard has a sloped landscape. It is a structure that holds back soil and prevents erosion. In this article, we will show you how to build a rock retaining wall step-by-step.
What is a Retaining Wall
A retaining wall is a structure built on a property to hold or retain soil and other landscaping features behind it. It can be made from various types of materials such as concrete blocks, poured concrete, timbers, or rocks.
Often built on sloped areas, a retaining wall helps prevent soil erosion and provide structural support for the property to keep it safe from unstable soil. A retaining wall can do a lot to improve the property’s safety, durability, and appearance.
Common Types of Rock Retaining Walls
Rock retaining walls come in various types. Here’s a brief overview of the common types of rock retaining walls to give you an insight of each and see which one best suits your yard.
1. Regular Rock Retaining Wall
This type of rock retaining wall uses natural stone materials such as granite, limestone, and sandstone. While natural stones are preferred for aesthetic reasons, they can also act as a way to control erosion in an outdoor area.
Meanwhile, rock retaining walls can be constructed without using mortar, relying solely on the weight of the stacked stones and friction in order to hold them in place. If constructed properly, natural stone can blend well with the aesthetics of the garden.
2. Freestanding Rock Retaining Wall
Free-standing retaining walls are built in an open excavation site and after the construction, the soil is then backfilled and compacted. It can be made from stacked rocks or boulders that were carefully selected, forming a natural-looking rock wall.
Freestanding rock walls are often used to add decorative yet functional elements to an outdoor space. Nowadays, we commonly see this in entrances to subdivisions, hotels, or condo developments.
3. Large Concrete Block Retaining Wall
A large concrete block retaining wall is a type of mortared retaining wall. Here, you have a very large block of stones with almost the same sizes, and then, you secure them with concrete.
Dry Stack Stone vs. Mortared Rock Retaining Walls
When building a rock retaining wall to your landscape, you can choose between dry and mortared stone walls. Let’s look at these two types of installing a rock retaining wall and the advantages of each.
1. Dry Stone Retaining Walls
A dry stone retaining wall doesn’t use mortar to join the stones together. It is also called gravity walls, dry-stack walls, and interlocking walls, among others. Advantages of this include the natural drain of water through the wall and you can make repairs easily.
2. Mortared Retaining Walls
On the contrary, mortared retaining walls used concrete to join the rocks together. Also known as a wet or concrete retaining wall, it provides an impeccable finish. It is a good choice for areas with high traffic as it keeps the stones tightly in place.
Essential Tools and Materials Needed
Here’s the list of tools and materials needed when building a rock retaining wall.
1. Equipment / Tools
- Maul or hammer
- Brick chisel
- Shovel
- Wheelbarrow
- Utility knife
- Rake
- Wood stakes
- Drag slings
- String line
- Maul and brick chisel
- Rake
- Hand tamp or rented power tamper
- 2×4 board
2. Materials
- Field stones or cut stones
- Deadman stones
- Compactible gravel
- Coarse sand
- Drainage gravel
- Perforated drain tile
- Drain tee fittings
- Drain gate
Step-by-step Process of Building a Rock Retaining Wall
Here’s a step-by-step process of building a basic dry-stack rock retaining wall. While each wall structure will differ on the dimensions and the specific type of rock used, most of the steps in this guide are still applicable regardless of those few differences.
1. Determine the Site and Dimensions
Decide where you’re going to build your rock retaining wall and then, lay out its dimensions using a string line. The dimensions include the wall’s width and its inward angle.
2. Sort Out the Rocks
Sort out the rocks according to size and shape. The flattest rocks are best used on the wall’s foundation for a firm base while those good-looking and smoother rocks are recommended to be placed at the top of the wall for a planar surface.
Meanwhile, those rocks with odd shapes and sizes can be placed between smoother and regular rocks for a better finish. With a maul and brick chisel, you can also smoothen some rocks if necessary.
3. Excavate the Area
When excavating the area, take note of the proper inward angle or also called the batter, as it is important for a better mass-controlling potential of the wall. The retaining wall will then look narrower at the top as compared to the bottom.
Now, dig out around 12 inches into the ground from the string moving back towards the slope. Excavate a smooth channel in preparation for the gravel base before the first layer of rocks.
4. Prepare the Base
Fill up the excavated trench with coarse gravel and flatten it using a rake. With a hand tamp or a rented power tamper, tamp it thoroughly. Then, add around a one-inch layer of coarse sand and level it with a short 2×4 board.
5. Lay the First Layer of Rocks
As mentioned earlier, those flat stones and preferably larger ones are best suited for the first layer or the base. You can start at the corner rocks first and continue along the front edge of the trench for the remaining base of the retaining wall.
While laying the first course of rocks, you may need to add or remove sand under each rock to set it firmly. Also, see to it that the stones across the layer are level by using a short 2×4 board.
6. Set the Next Rock Layer
For the next layer, choose those rocks that will bond well with the base rocks. Then, start further inward for about half of an inch, creating a slightly backward-leaning layer. This is important to have a strong retaining wall that will hold back the soil properly.
Continue setting this layer of rocks along the base of your retaining wall. After that, fill up those leftover gaps with smaller rocks.
7. Backfill the Wall
After laying the first two layers of rocks, backfill the wall with gravel. Then, level the gravel flat by using a hand tamp. This will secure those layers as you continue the process to get to the top of the wall.
8. Set Up a Drainage System
Once a few layers have been stacked together, set up a drainage system by laying down perforated drain tile on top of the rock. It is recommended to install drain tee fittings and a drain grate every 25 feet to 50 feet.
You may need to cut one block down in order to place the drain grate. For a durable connection, screw the drain tile parts together as they will be covered with more rock later on.
9. Continue Fitting the Rocks
Follow the same process on the second layer for the subsequent courses of rocks. Remember to add half an inch of batter for every layer. On the third layer, install “deadman” stones for more stability.
“Deadman” stones are long stones that reach back into the slope and help attach the wall to the soil at its back. Place it every 6 -8 feet around the entire wall. As you go with the process, backfill the wall with gravel.
10. Lay the Final Course on Top of the Wall
Once the retaining wall reaches the desired height, it’s now time to lay the final course on top of the wall. Pick those rectangular and smoother rocks for the final layer and secure them properly. Avoid lengthy joints and see to it that there is no shaking.
Cost of Building a Rock Retaining Wall in Brisbane
In Brisbane, expect to pay the following when building a retaining wall using these specific materials:
- $300 – $550 per m2 for sandstone blocks
- $400 – $680 per m2 for reinforced concrete blocks
On the other hand, there are a number of factors that can affect the cost of building a rock retaining wall such as the following:
- The specific type of rock material used
- Size and scale
- Height
- Design, which includes the excavation and drainage requirements
Top Retaining Wall Builders in Brisbane
Here are some retaining wall builders in the Brisbane area. Contact them for inquiries and quotations.
1. Cropper Bros Retaining Walls
Cropper Bros Retaining Walls & Fences is a Brisbane-based company founded by brothers Steven and Peter Cropper. With their QBCC Builder restricted licenses, they deliver quality finishes on any retaining wall or fencing requirements.
WEBSITE: | https://www.cropperbrosretainingwalls.com.au/ |
ADDRESS: | Thomas St, West End QLD 4101, Australia |
CONTACT INFO: | +61 422 103 566, [email protected] |
OPERATING HOURS: | Monday – Sunday: Open 24 Hours |
2. Bluestone Retaining Walls & Fencing
Bluestone Retaining Walls & Fencing was founded by Craig Heness who has more than 25 years of experience in the industry. They are passionate about providing quality service, from the client’s inquiry to the completion of the project.
WEBSITE: | https://www.bluestonefencing.com.au/ |
ADDRESS: | 25 Northmarque St, Carseldine QLD 4034, Australia |
CONTACT INFO: | +61 488 180 991, [email protected] |
OPERATING HOURS: | Monday – Friday: 7AM-5PM |
3. Triple A Constructions
Whether it is for a residential property or a commercial one, Triple A Constructions can help you design a value-for-money retaining wall solution. They source high-quality materials in various types and styles to match any space.
WEBSITE: | https://www.brisbaneconcreteretainingwalls.com.au/ |
ADDRESS: | Wishart QLD 4122, Australia |
CONTACT INFO: | +61 415 659 250 |
OPERATING HOURS: | Monday – Friday: 7AM-4PM, Saturday: 7AM-12PM |
4. Concrete Sleeper Retaining Walls
CS Retaining Walls Brisbane is a one-stop shop for various retaining wall needs. They have an extensive range of styles to choose from and they partnered with trusted installation partners to help build the best retaining wall solution for their customers.
WEBSITE: | https://concretesleeperretainingwallsbrisbane.com.au/ |
ADDRESS: | Unit 7/237 Fleming Rd, Hemmant QLD 4174, Australia |
CONTACT INFO: | +61 7 3393 9647, [email protected] |
OPERATING HOURS: | Monday – Thursday: 6AM-4:30PM, Friday: 6AM-2:30PM |
5. RYCAN Retaining and Earthworks
Rycan Retaining and Earthworks offers excavation and structural landscaping services including retaining wall building. They serve throughout the Brisbane Western Suburbs as well as the Ipswich regions of South East Queensland.
WEBSITE: | https://www.rycan.com.au/ |
ADDRESS: | 3 Jingara Ct, Karana Downs QLD 4306, Australia |
CONTACT INFO: | +61 400 320 962 |
OPERATING HOURS: | Monday – Wednesday: 7:30AM-4PM, Friday: 7:30AM-4PM |
Benefits of Having Rock Retaining Walls
While rock retaining walls are functional structures that retain soil on a sloped area, they bring a lot of other advantages too. Here are some of the benefits of having rock retaining walls and why it might be the right choice for your outdoor space.
1. Rock is a Very Strong Material
A rock retaining wall can be a very strong structure if built properly. It can withstand Brisbane’s often harsh climate, including hot weather and severe storms. Functionality-wise, rock is capable of retaining tonnes of dirt and other stone fragments.
2. Requires No Maintenance
Using rocks for the construction of walls is considered an ancient form of masonry. As such material won’t rust, rot, or need cleaning and polishing, it doesn’t require maintenance. Once built, it is set in place and good to go.
3. Prevents Soil Erosion
The main function of a rock retaining wall is it prevents soil erosion and thus, it protects the surrounding structures and buildings from possible damage. In Brisbane where heavy rainfall is frequent, such structure helps to prevent flooding and soil movements.
4. Provides Structural Support
Having a solid foundation for any home is important as it provides the structural support necessary to keep it safe. This is especially true if your lot is located on an incline. A retaining wall can protect the integrity of your foundation by keeping the soil in place.
5. Boosts Curb Appeal
A rock retaining wall is an aesthetically-pleasing upgrade that can add a curb appeal to your home or property. Natural materials such as rock can blend well with other features in your yard, providing a beautiful end result.
6. Adds Value to Your Property
With all of those benefits previously mentioned, a rock retaining wall adds value to your home or property. Such investments in landscaping appeal to many buyers which means higher property and resale values.
Building a rock retaining wall is a great way to add curb appeal to your home. A properly-built retaining wall can last for decades. Here, we discussed the necessary steps on how to build a rock retaining wall which can guide you when building your own.