So you’ve finally decided to take on the backyard and build a retaining wall. Great choice! A DIY retaining wall is much easier than it seems, and you’ll be amazed at how awesome it looks once you’re done. Laying out retaining wall blocks can be tricky, though, especially if your wall is more than one level high. Here’s how to lay out your blocks perfectly so that building the rest of your foundation will go smoothly:
Things you need to lay retaining wall blocks
You will need the following tools and materials to lay retaining wall blocks:
- Brick trowel (for larger projects)
- Safety glasses, dust mask and gloves for safety.
Remove the sod
- Remove the sod with a spade or sod cutter (use caution when using a spade as you may accidentally damage nearby plants).
- Use a sod stripper if you have one (do not use a shovel).
- Do not use a lawn mower, weed whacker or any other cutting device that has sharp edges to remove grass.
Dig the trench
Trenching is the first step in laying your retaining wall. The trench should be dug to a depth of 8 inches, at least 1 foot wider than your block size, and level with the surface of the existing ground.
Once you’ve dug your trench, tap along its edges with a straight-edge board to make sure it’s straight and plumb; if necessary, use stakes placed along opposite sides for reference points as you work.
Add base material
- Use a backhoe to add base material.
- Use a shovel to add base material.
- Use a wheelbarrow to add base material.
- Use a pitchfork to add base material.
- Use a rake to add base material
Assemble the first course of blocks
To ensure that the first course of blocks is level, straight, and plumb (at right angles to the ground), use one or more of the following methods:
- Use a level. Lay a level across each row to check for level.
- Use a straight edge. Place the straight edge against each block in turn and adjust it until it touches both ends of each block without rocking back and forth; then check this same row for plumb with a plumb bob or string (see next section).
- Check every other block along all four sides using either method above until you have checked two courses’ worth of blocks; then move on to laying your second course and repeat these steps.
Ensure blocks are level, straight and plumb
To ensure that the blocks are level, straight and plumb (vertical), use a level to check for level, a straight edge to check for straight, and a spirit level or line level to check for plumb. You may also use a laser-based tool called an inclinometer which is used in many construction fields as well.
Use temporary stakes to keep things in place as needed
When laying your blocks, it’s important that they’re as level and straight as possible. To help achieve this, you can use temporary stakes to hold them in place until the mortar dries. The stakes should be at least 1/4″ taller than the block height (and preferably slightly taller), so that once they are removed, there is enough room between the top of your wall and surrounding ground for drainage.
Stakes should be placed inside each trench where it is appropriate; you don’t want to stake too far away from your wall because this will require unnecessary digging later on when you remove them! If possible, try spacing them out at 6′ intervals rather than 4′, since they’ll provide more stability when working with larger walls like those shown here.
Dig behind the block and add more base material – backfill
- Dig behind the block where it meets the ground. Use a shovel to excavate an area of base material which is larger than the block and backfill with additional material.
- Level out the base so that it’s as even as possible. This will help prevent any sagging in your retaining wall over time.
- Backfill with additional base material, filling in from behind each brick, making sure that all gaps between bricks are filled with more dirt or gravel so that no water can get through them (this will create leaking issues later on).
Continue adding base material and building up new courses of block until you’re happy with the height.
Once you’ve got the first course of block in place, continue to build up the wall using the same method. When laying up the second course, make sure that it’s level with (or higher than) your first course of blocks.
If you want a more precise way to ensure that your next course is level with your previous one, use a spirit level. If you don’t have access to one, use something else that has some weight and can be used like a plumb bob—a chunk of wood or brick will do just fine.
Place this object between your two levels and adjust accordingly so they are aligned correctly. You can also use string lines if you prefer; however, these can be difficult to keep straight when working with multiple people unless each person is responsible for their own portion of string line during construction.