If you’re installing a retaining wall, you’ll almost always have to cut some blocks to fit. That’s true whether you’re using concrete blocks, brick, or another material.
In either case, you should have a few blocks on each end that don’t quite line up. Luckily, cutting those retaining wall blocks is a relatively easy job.
Fortunately, cutting retaining wall blocks is relatively easy. If you only have a few blocks, you can make do with a hammer and a chisel. On the other hand, if you have a lot of blocks, you’ll want to rent a masonry saw or buy a masonry blade for your skill saw.
How to Cut Retaining Wall Blocks
In most cases, you’ll want to know how to cut retaining wall blocks by hand. Here, you’ll need a simple toolset and some patience.
However, if you only have to cut a few blocks, a chisel is more than effective enough. In addition, it works whether you’re using stone, hollow blocks, or whole cement blocks.
Things You’ll Need:
- Masonry chisel (1” or larger)
- Measuring tape
- Square angle
- Safety glasses
- Heavy hammer
1. Measuring the Cut
Use a measuring tape to determine how long your block should be. If you have to cut at an angle, you should mark that on the block as well.
Then, use a square to mark the length on your retaining wall block. You can also just use a measuring tape and chalk. However, the square ensures the lines are straight to the block – so the block will fit better.
You’ll want to trace the line all the way around the block. However, if you’re using chalk, you may want to do one side at a time, so the line doesn’t rub or wear off when you turn the block.
2. Scoring the Line
Place your masonry chisel on the block and tap the top of it with a hammer. Slowly move the chisel from one side of the block to the other, until you have a neatly scored line.
These scored lines don’t have to be exact. Instead, they’re primarily to prevent the surface of the block from chipping when you split the block.
In most cases, a line of about 1/16th inches deep is good enough. However, you don’t have to be exact.
3. Splitting the Retaining Wall Block
Place your block on a sturdy, flat surface. Here, either a bed of other blocks, a paved floor, or a well-packed dirt floor will work.
Then, simply insert the chisel into the scored line and hit it with a hammer until the block splits. Here, your chisel should normally be towards the center of the block.
What else? It’s also a good idea to mark the widest angle of the block, because this reduces the depth of the crack. The taller your retaining wall blocks, the more likely you’ll have to clean up the split with a chisel after.
Additionally, if you have a hollow cement block, you’ll want to try to split from the side, with the hollow side open to the sky. That’s because if you try to split the panels with nothing underneath, they will simply break.
So, you’ll have to break each long side of the hollow block separately. For this reason, many people prefer to cut hollow blocks with a saw rather than using a chisel.
4. Cleaning Up
If you don’t get a perfectly even split, you can clean up any burs or protruding bits of cement or stone with your chisel.
To do so, simply set the chisel against where you’d like it to break. Then, tap with your chisel to create a new line at the top. From there, you can hit the chisel with a hammer until the bur splits off.
If you have a protrusion in the middle, you’ll have to set your chisel at an angle to properly cut into the stone. However, this is unlikely unless you have a rock or stone retaining wall.
Using a Saw
While cutting retaining wall blocks without a saw is the cheapest option, it will be very time-consuming if you have more than a few blocks.
For this reason, you may want to use an electric saw instead. Here, there are a few different tools that will do a similar job:
- Masonry saw (available for rent at most hardware stores)
- Masonry chopper (Available for rent at most hardware stores)
In addition, you can use a skill saw with a masonry blade and a chisel.
- Skill saw with masonry blade
- Angle grinder with masonry blade
Neither of these two options are suitable for thick blocks unless you also use a hammer and chisel. However, they will greatly speed up the process of scoring the blocks, which will cut the time to split blocks in half at worst.
To start, follow the same measuring steps as you would for hammering. Then, put on safety goggles. Make sure you have a masonry blade on your saw or grinder.
Then, score the lines with the saw. It may be a good idea to hold your block in place by putting other blocks around it, on the sides you’re not cutting.
If your blade is long enough, you’ll also want to raise the block you’re cutting off the ground. To do so, place two blocks under it, close enough together that the two halves won’t collapse when you cut through them, but far enough apart to allow the blade to pass through.
Importantly, cutting through stone, cement, or brick will put a large amount of torque on the brick. It’s never safe to cut it without stabilizing the block first.
In addition, it’s not safe to cut the block while holding it, even if you have a stationary table saw to do the work. Always lay the block flat and use clamps or other bricks to hold it in place.
If your blade isn’t long enough to cut through the block in one go, flip it over and repeat the cut on the other side. You might also want to use a hammer and chisel to finish the cut.
Finally, pay attention to the blade you’re using. Many masonry blades should be used wet.
In addition, if you’ve rented a wet saw, you may also want to completely soak your blocks before cutting them. If you’re cutting stone blocks, you’ll also almost always have to wet them to reduce heat and friction.
Accomodating Corner Cutting
Building any retaining wall corner should be a simple matter of cutting corners on your blocks. Here, you use a simple square and any cutting method you’d like.
To cut a perfect corner, you simply want to mark a 45-degree angle. From there, you can score and cut the block in whatever fashion you used to cut the rest of the wall.
If you’re cutting a retaining wall in a circle or an S shape, you’ll have to use different angles. Here, the angle depends on the size of the block and the wall.
Your best option is to lay out the blocks stacked two high, in the shape you want and overlapped to get the shape you want. That will allow you to calculate the angle for a good cut to get the shape you want.
And, if you are doing an S or circle, you’ll have to cut both sides of the brick with the angles inverted. That will be a lot of work without a saw, so consider renting one if you’re doing a project like this.
Frequently Asked Questions
If you still have questions about cutting wall blocks for a retaining wall, these answers should help.
Do you have to cut your retaining wall blocks?
Not always. In some cases, you can get away with aligning some of your blocks in the opposite direction. This will cut into your soil area. However, it may mean you can avoid cutting blocks at all.
However, this method will also waste blocks. So, if you’re on a budget, it’s always better to cut the blocks and try to use the other half of the block somewhere else.
Can you cut stone blocks?
You can easily cut most stone blocks using the same method above. However, it’s important to note that if you have a sediment rock type such as shale or limestone, it could shatter when you hit it with a chisel. For that reason, some types of stone are better cut with a wetsaw.
Do I need a wetsaw to cut yard blocks?
It’s often unnecessary to use a wetsaw to cut yard blocks for your retaining wall. However, if you have to cut a lot of blocks, these saws may be a great idea. That’s also true if you’re trying to cut rock that shatters easily.
Cutting retaining wall blocks is relatively simple but it can be very labor-intensive. If you’re splitting your retaining wall blocks by hand, you should expect to spend a significant amount of time on every stone.
However, you might also choose to rent a masonry saw or buy a masonry blade for your skill saw or angle grinder. In either case, make sure you wear safety goggles and long sleeves while doing work to prevent being hurt by flying shards.
Good luck finishing your wall.