When your yard contains a sloping section of earth, you may need to build a retaining wall to help with your yard's landscaping and keep the soil from eroding away downhill. To make your retaining wall strong and effective, it needs to have proper water drainage and be built to hold its structure. Here are three tips to help you build a successful retaining wall.
Build a Sturdy Wall Base
The first step in building your retaining wall is to excavate the soil around where your retaining wall will be built. Dig out a section of soil 12 to 15 inches into the hill to provide space for your wall's drainage system. Line the soil with landscape fabric from the base of where your wall's foundation will be set and up behind your excavation area. This layer of landscape fabric will keep your drainage system gravel in place.
If you live in an area that freezes during the winter, determine how deep the frost line extends into the soil and dig the wall foundation just below that. In areas that do not freeze, you will need to bury one tenth the height of your retaining wall in the soil to prevent your wall from buckling from freezing damage.
The best type of material to use to build your wall is concrete blocks that have locking flanges to hold the wall's structure together. These flanges allow you to build a sturdy retaining wall without using mortar or cement. The flanges will also help construct your wall with a slope toward its load, increasing its weight-bearing capability. Set the bottom base row of blocks upside down, with the flange on the top outside of the wall to help increase your wall's integrity.
Add an Exterior Drainage System
If your retaining wall does not have a drainage system, water can collect in the soil behind the wall and push the wall outward, eventually collapsing the wall. If this water freezes during the winter, the expanding ice can push your wall outward and damage it.
At the base of your retaining wall's foundation, spread a layer of gravel at least four inches deep, then place a four inch perforated drainage pipe on top of the gravel. Provide a drainage opening where water collecting inside your perforated pipe can exit from the drainage system and surrounding soil. You can install a drainage outflow at either end of the retaining wall, or at any location along the retaining wall's length. Cover the pipe with gravel.
Backfill Behind the Wall
As you build the wall, add gravel between the wall and the landscape fabric and replace soil to the other side of the landscape fabric. Slope the gravel layer upward one inch for every four feet of length away from the wall for water to drain.
It is important to replace and pack the gravel and dirt inside your wall as you add each row of blocks to construct the wall. If you replace the gravel and dirt behind your wall at the end when the wall is constructed, the soil may not fully compact and your soil will sink in later. This would cause damage to your wall's structure.
When you finish building your retaining wall's final row of blocks, cover the layer of drainage gravel with a six-inch layer of topsoil. This soil will provide a spot for you to grow landscaping plants right up to your retaining wall. The roots of the plants will keep your soil from eroding and keep your retaining wall's underlying gravel layer intact.
Use these three tips to help build a strong, well-drained retaining wall. For more assistance with constructing a successful retaining wall, contact a waterproofing company, such as Rite-Way Waterproofing.