We Choose the Materials for Your Foundation
Once we have created a level trench using a square spade and line level, it’s time to choose the materials for the foundation of your natural stone retaining wall. Here, we usually use gravel, crushed stone, or clay depending on the area in which we are building the wall. Below, we break down the benefits of each so that you can have a better idea of why we choose the materials that we do:
Gravel
Looking for a good option for water drainage? Gravel is your best bet! Gravel leaves large gaps that allows for better drainage, preventing the wall from moving.
The key to laying down gravel is to spread it evenly before compacting it with a jumping jack or vibrating plate compactor. We will be sure to avoid directing your drainage system towards your house to prevent damage.
Crushed Stone
At New Life Rockeries, we often use crushed stone rather than gravel or concrete because, despite being a little more expensive, it requires less compacting and provides better drainage. Typically, the crushed stones we use are between half an inch and three quarters of an inch because they are better suited for the freeze and thaw cycles the Pacific Northwest experiences during the winter months.
Clay
On the other hand, clay does not provide the best drainage so if you live in a wet area and want to use clay, it’s important that we slope your drain away from the face of your retaining wall so that it can drain correctly. Alternatively, we can slope it to the left or right so that it drains to one end or the other.
In very rare cases, we can install a drainage system underneath the wall, however, this can lead water to gather underneath so we tend to avoid this method. If there is no other drainage method, we can install a drain far enough behind the wall blocks. Whatever method we agree on, our goal is to always prevent erosion and the build up of sediment in your drain.
Soil
Soil can be a challenging material to use for the base of your retaining wall. That said, there are some instances where it can be useful. At New Life Rockeries, we use soil under the following circumstances:
- The building area has been untouched for decades
- There is an existing slope facing the wall
- We are building a short wall with less weight
- The lawn has been there for decades and slopes away from the wall face, making it great for drainage
While we do install retaining walls on soil in the circumstances above, we try to avoid this wherever possible, opting for bases like concrete and gravel instead. This is because, over time, if we install a wall on soil instead of concrete or gravel, the bottom section of the wall will absorb more weight, leading the retaining wall to lose its integrity and sag.
Many other contractors use sand and silt as a base for their walls. These can clog more easily, causing drainage issues along the way. We prefer to use clean materials that are compacted to create an even and level base to install your wall. These clean materials are essential to the foundation of your wall and its future integrity.
Our promise to You Regardless of the Base materials used
Whether we use gravel, crushed stone, concrete, soil, or sand, or any other material, we create all of our walls on a slope for optimal drainage. Moreover, we will ensure that the front face of your your wall will have sufficient stable ground in front of it to maintain its integrity and prevent erosion.
Last but not least, if the slope is steep, we will check that there are at least a couple of feet of strong ground in front of your retaining wall to ensure its durability. Above all, we promise you a wall that lasts, with a good draining system for water, that is the correct number of feet away from other structures, and that keeps the slope of your garden in mind for best results.
We Plan Stone Placement
Stone placement is essential to the integrity and structure of your retaining wall. Of course, we will ensure that the base of your wall is wider than the top, using larger stones on base course in order to lay a solid foundation. We will also use large stones behind the base course, spreading the weight of the bottom course to lay the foundation for the first course and final course.
Above everything, we will make sure that your wall blocks are level in order to maintain a high level of structural integrity. We will never use flat stones that slope towards the front edge of your wall nor will we use flat stones that slope towards the back as this will prevent holes and collapses.
At New Life Rockeries, each of our walls are created by our best contractors. We will plan every square foot of your wall with beauty, structure, and longevity in mind so that you can rest assured knowing that your wall will stay with you for years to come.
We Set Up & Level the First Layer of Stone
Once the base layer is installed and we have chosen and organized the stones, we will work on building the first course of your wall. During this stage, we will use a line level to ensure that the wall is built evenly. We’ll then brush of the first course of the wall before moving onto the next one to ensure that second course is in alignment.
We Set Up Your Drainage System
Drainage is one of the most important elements when it comes to installing a retaining wall. That’s because stone retaining walls can quickly tumble and fall if they’re met with pressure from excess water and sediment. With this in mind, we set up your drainage as soon as we have your first course and second course stacked.
Once we have laid down your first and second course, we backfill the stone retaining wall with rock. Then, we place perforated drain tile on top of the rock and use drain tee fittings and a drain grate every 20 feet to 60 feet depending on the amount of rainfall you expect in your region. We’ll then screw the drain tiles together so that they stay together during the rest of the construction process.
We Protect Your Wall With Backing
There is one force of nature that can always bring a stone retaining wall tumbling down if it is not built well: Rainfall.
Over time, water accumulates behind your wall, and while this should not cause any harm, the sediment and debris it brings with it can. When the backing of gravel and earth become clogged up, the ground materials can leak through the spaces of your wall’s stones. This can cause instability, whereby your wall starts to move inwards into the unstable ground. If it moves outwards, the wall could lose strength, collapsing altogether.
Luckily, you won’t have to worry about rainfall because we will back your stone retaining wall with landscape fabric known as geotextile. This will cover the entire backside of your wall and let the water flow through without letting solid materials pass. This landscape fabric will keep your wall clean while not disturbing the new structure that our team has created for you.