A poorly built retaining wall is a threat to your clients and your business. Avoid costly callbacks from structural failures and protect your bottom line by using the right landscape adhesive and following the professional tips outlined in this retaining wall installation guide.
A sloped yard presents a variety of issues, including constant topsoil erosion, mowing challenges, and water runoff.
Well-constructed retaining walls optimize land use by transforming unusable slopes into valuable spaces for lawns, gardens, and patios.
The difference between durability and failure boils down to proper retaining wall installation. A structurally secure wall should have a solid foundation, proper drainage, and robust construction.
Even the most well-constructed wall can lean, shift, or fail without proper surface preparation. This step in the retaining wall installation process includes clearing the site and compacting the soil to ensure your wall stands strong for many years to come.
Before building a retaining wall:
1. Assess the yard: Determine the wall height, water flow, soil type, and slope. These aspects have a direct impact on the footing depth, drainage solutions, and materials to be used.
2. Mark the site: Use a string and stakes to mark the wall layout. Measure the slope angle with a line level and determine whether to use a tiered wall or a stepped base approach.
Pro tip: Don’t forget to contact the utility company before digging near irrigation or electrical lines.
3. Clear and level the area: Now that you know the wall’s intended footprint, remove any roots, organic matter, and debris. Then dig a trench that can accommodate between 4 and 6 inches of gravel and a base course.
4. Compact the soil: Prevent the soil from settling over time with proper tamping. Use a professional-grade tamper to firmly compact the trench base.
Pro tip: Compact the soil in stages. Add layers of gravel or crushed stone, compacting each layer before moving to the next one.
If you want to avoid unnecessary callbacks and ensure your work stands out from the rest, proper retaining wall drainage is essential to a safe, lasting build. Without an outlet, water builds up pressure, causing bulges, cracks, and eventual failure. You can prevent this by using different drainage solutions, including:
- Drainage aggregate layer: A one-foot-deep stone aggregate column that allows water to drain away quickly.
- Gravel backfill: This is a quick-draining zone made up of at least 12 inches of ½- to 1½-inch angular, crushed, open-graded aggregate.
- Filter fabric: Guarantees long-term performance by keeping soil from clogging up drainage systems.
- Perforated drain pipes: Made up of pipes installed at the base of the wall to redirect water away and relieve pressure.
- Weep holes: These are small holes spaced between 3 and 7 feet apart to allow the passage of water.
Consider the factors below when deciding on the best strategy for different projects:
1. Wall location and water sources: A wall built at the bottom of a hill will have to deal with more water runoff than one on a relatively flat area. Are there any nearby water sources, such as lawn irrigation systems or downspouts, that could saturate the surrounding soil?
2. Soil type: Different soil types handle water differently. While sandy soils drain quickly, they require additional support, such as a geotextile fabric, to prevent them from washing away. On the other hand, clay soils require a strong drainage system because they retain a lot of water, which exerts significant pressure.
3. Wall materials: You need a robust drainage system when using nonporous materials like cinder blocks or concrete to build a retaining wall. These materials do not have natural gaps for water to drain through, which can lead to rapid pressure buildup.
4. Wall height: Generally, the pressure behind a retaining wall increases with height. A simple gravel backfill is suitable for walls up to four feet high. For walls between four and six feet, an engineered drainage solution integrated into the backfill is required. For walls over six feet, you need a detailed plan from a professional engineer.
To build a durable retaining wall, you need a reliable adhesive like Loctite PL Max Landscape Adhesive. Specifically designed for outdoor projects, this adhesive is weather-resistant, durable, and offers exceptional gap-filling capabilities. This makes it great for bonding irregular surfaces.
For proper application, follow the steps below:
1. Clean surfaces: Use a wire brush to remove all debris and dust from the brick surfaces.
2. Pre-fit the blocks: Arrange the blocks to ensure proper alignment, consistent stagger, and correct level before permanently bonding them. Eliminate vertical weak points in the wall by staggering vertical joints across courses.
3. Apply retaining wall adhesive: Install the cartridge into a caulking gun and cut the tip to the required bead size. Depending on the material, you can apply the adhesive in a wavy or zigzag pattern, dots, or lines.
Pro tips:
- This waterproof adhesive can be applied in all weather conditions, including temperatures ranging between 10°F and 120°F.
- For the best results, use a 1/8-inch to 3/8-inch bead for most applications.
- If you use parallel lines of adhesive, space them about four inches apart.
- Avoid trapping moisture between the joints by using broken beads of adhesive instead of continuous lines.
- Avoid over-application of adhesive, which could lead to wastage and result in a mess that affects the final appearance of the project.
4. Lay the blocks: Fit and press the blocks together within 10 minutes of applying adhesive.
Pro tip: Apply force by placing a weight, such as an unused brick, over the ones you have laid to achieve a tighter fit.
PL Max Landscape Adhesive sets in about 24 hours and cures completely within 7 days. The exact curing time may vary depending on material porosity, humidity, and temperature.
Pro tips:
- When working in ultra-low humidity conditions, lightly misting the substrates can accelerate curing.
- Accelerate the rate of curing in extremely low temperatures by providing supplemental heat.
- Always respect the product’s gap-filling specifications to avoid curing issues due to excessive joint thickness exceeding cure capacity.