15 Apr Retaining Wall Installation Tips
Excavation & Base Preparation
Set an excavation line using a chalk or string line. To create an accurate radius, drive a stake into the ground at the desired center of your project. Attach a string to the stake equal in length to the desired inside radius. Rotate the string to indicate the location of the back of the first course. Once laid out, excavate a trench equal to the depth of gravel material plus the height of one unit, or to firm soil. The trench should be approximately 100-150 mm (4-6″) wider than the wall block you have chosen.
After excavation, spread the base material uniformly throughout the trench with a hard toothed rake in layers of no more than 100 mm (4″). Use the vibrating or hand tamper to compact the entire area evenly. Continue spreading and compacting base material until the desired depth is achieved and the surface has no low or high areas.
Place screed rails at the desired grade of the underside of the first course of wall. Level the screed rails with a 4 foot level or a transit level. Place granular base material between the rails and screed level with a straight edge, such as a 2×4 timber. Compact this area with a hand tamper. After compacting, place more granular base material between the rails and screed level. This is the level surface for laying the wall base pieces.
Base Course & Wall Construction
Start placing the base course on top of the compacted base, beginning at the lowest point of the wall. Check alignment and leveling as you proceed. Continue with additional courses, adding and compacting backfill material behind the wall after every second course. To ensure adequate interlock between courses, we recommend a minimum joint overlap of 1/4 bond.
To ensure good color distribution, take pieces from several bundles at a time, removing them in stacks rather than by layer. Tip: Check the levelness of the wall every 2-3 courses by putting a string line along the length of the wall. Shim or adjust the blocks as necessary to keep the wall lines straight.
Express your creativity with Hanson retaining walls. Several of our retaining wall systems enable you to create Wall Art – a completely unique expression of your style. Simply turn the blocks during construction to create repeating or random patterns in the face of the wall. The exclusive “end grooves” feature on our XL Pro Wall and Wallstone blocks enable you to place blocks vertically and set them forward or back from the face of the wall to create interesting surface graphics while still maintaining the tongue and groove interlock. For garden and decorative walls, Antique Hampton Wall is an ideal product for creating beautiful, multi-dimensional patterns.
Building corners with Hanson retaining walls is easy, whether they are curved, square or at any angle. Create curved corners using any of our wedge or taper blocks by simply laying the pieces in their natural curve. For gentler curves, gap the back of the pieces to fit the desired radius. Keep in mind that gaps in the wall layout will mean gaps in the coping (top) course unless pieces are cut to fit.
Building square corners is equally simple with Hanson retaining walls. We strongly recommend building a finger jointed corner as it is the strongest corner that can be built. In addition, it is recommended that you use a landscape adhesive between all courses at the corner for increased strength.
The coping course adds the finishing touch to your wall project. Because of the tongue and groove features of many Hanson walls, the coping course offers multiple placement options – set it forward or in line with the rest of the wall, or use a wider coping piece and center it over the rest of the wall. Whatever placement option you choose, the coping pieces are simply set on top of the rest of the wall. An adhesive should be applied in two continuous beads along the outer edge of each top rib of the course below the coping. This will secure the coping to the rest of the wall.
Steps can be built using any Hanson wall products. The base underneath and behind a step remains the same as the base underneath and behind a wall. Tread width can be customized by installing Hanson pavers. When including steps as part of a larger wall, build the main wall and the returns first, then construct the steps.
Using Wall Systems in Combination
Many of our wall systems include both straight and wedge or tapered blocks that can be used alone or in combination for maximum flexibility. The XL Pro, Wallstone, RB and GRANDE systems can easily accommodate straight, curved or combination walls.
There are a few tricks that can assist you with combining two wall systems in one wall:
- You may have to gap blocks at the back of the wall every second course to make the blocks sit properly. A gap of 75 mm (3″) is acceptable for Wedgestone Wall and XL Pro Wall and 130 mm (5″) is acceptable for GRANDE Wedge.
- The second course may not have exactly the same configuration as the course below it. Once again, gapping the blocks may be necessary. In a vertical wall, the first course will match the third course, the second course will match the fourth course, and so on.
- You may need to remove or modify some of the ribs on the bottom of the block to make the next course sit flat. Removal of ribs is acceptable but should be kept to a minimum, as this is the primary connection mode between courses.