Is a sudden slope in your yard preventing you from achieving the landscape you want? One way to even the score is by building a retaining wall. By replacing the slope and leveling the yard to either side of the wall, you can create two distinct tiers for split level form and function.
Landscape blocks are some of the best things to happen to walls in a long time. Made of precast concrete, they have textured faces that make them look a lot more like stone than concrete. The blocks are durable and can easily be cut into smaller pieces to offset courses as you build your wall. They require neither footing nor mortar, and stacking them automatically creates a wall that leans into the hillside for strength.
Landscape blocks come in two major varieties, lipped and pinned. The retaining wall in this project uses lipped blocks. For any wall four feet or higher, consult a professional rather than tackle it yourself. The Home Depot offers installation services for many products. And any time you plan a project that involves digging or reshaping your land, be sure to call 811 first to find out the location of utilities in your yard.
- Construction adhesive
- Drainpipe (optional)
- Landscape blocks
- Landscape fabric
- Mason’s line
- Sand (optional)
- Beam level
- Circular saw with a masonry blade
- Rubber mallet
- Torpedo level
1. Dig and level a trench
Lay out the wall with batterboards and mason’s line. Dig a trench as wide and deep as the manufacturer recommends. Line the bottom with an inch or so of sand, rake it level, and compact it with a tamper. Place some of the soil you remove on the downhill side of the trench to level the slope. Line the back and bottom of the trench with landscape fabric. Unroll enough fabric to cross back over the trench later, plus about a foot more than the height of the wall. If you have to piece together lengths of landscape fabric, overlap any adjoining edges by 3 to 4 inches.
2. Lay the first course
Some manufacturers instruct you to set the first block lip up; others instruct lip down. Follow the directions. Lay the first block and check its level from side to side and front to back. Tap with a rubber mallet to make small adjustments. Put sand under the block to solve bigger problems. Lay the remaining blocks one at a time. Make sure each block is level, checking both side to side and front to back. Put the level across the new block and at least one of its neighbors to make sure the tops of the blocks are level with each other. The spaces at the ends of the course may not require a full block. Buy smaller blocks or trim larger ones to fit.
3. Lay the second course
If the first course ended with a full block, begin the second course with a half block. If you started the first course with a partial block, trim a full block so it overlaps the seam below by at least 3 inches. (Check the manufacturer’s instructions.) Lay a second course of blocks with their lips pointing down, over the back of the wall. Position each block so it spans a joint in the course below. As you work, verify that the blocks are level; if not, shim the low end with asphalt shingle or some landscape fabric. As you come to the end of the wall, trim a block to fit in the opening. When you begin building the rest of the wall, alternate so one row begins with a full block and the next with a half block.
4. Lay a third course and some drainpipe
Not all block walls require a drainpipe, though it’s never a bad idea. Lay the third course the same way you laid the second course, leaving an exit point for the drainpipe at one end of the wall. Add a bit more gravel behind the wall to create a flat surface, and tamp the gravel. Tuck a drainpipe behind the wall. Fill in completely behind the wall to the top of the course and tamp. Continue building the wall, adding gravel and tamping after every course. When you’re a course or two below the top of the wall, fold the landscape fabric over the gravel and trim off any excess.
5. Lay capstones
The keystone shape of the blocks leaves triangular gaps between the stones, which are covered up with special blocks called capstones. Apply a bead of construction adhesive along the top of the wall and set the capstones in place. Put topsoil in the space between the landscape fabric and the top of the wall and fill what remains of the trench in front of the wall. Rake to make a flat surface and tamp.