In this article we will talk about how to build a cinder block retaining wall on your own. Chances are, if you ask three builders how to build a concrete block retaining wall, you are going to get three very different answers. So we will take a look at some of the options you will have and recommend the best way to build your own cinder block retaining wall. It is not too difficult, but there are a few concerns that have to be dealt with.
Of the few challenges that you will encounter when faced with building a retaining wall out of cinder block, these are the most important. The attributes you need for a good retaining wall are good strength, proper irrigation, longevity and stability.
You may say, why use cinder blocks instead of solid blocks, but remember, cinder blocks can be filled with cement and they become solid. Plus they have handy hollow centers that can be used to run reinforcement materials through. So, cinderblocks make a great building material for retaining walls.
Strength is one of the most important attributes of a well built retaining wall. Cinder blocks filled with concrete with steel rods running though the center offer all the strength you need in a retaining wall.
Proper irrigation is a must. You have to pay attention to the environment that you are constructing the retaining wall in. The main goal is to divert as much water away from your wall as possible. Then any water that can’t be diverted from the wall completely, needs to be able to pass through the wall easily so it doesn’t cause erosion of the retaining wall over time.
There are several way to provide draining though a wall. Most commonly used probably is PVC pipes run though the cinder blocks. Normally you want to use a ½ – 1 inch PVC pipe cut to the thickness of your wall or eight to ten inches in most cases. It is a good idea to have one pipe installed between each block near the base of the wall.
The drainage pipes should exit the front of the wall just above ground level. In most cases the rear of the pipe will be covered with fill dirt. Instead of just covering with fill dirt though, make sure to have some loose rocks or gravel around the ends of the pipes to allow water to flow better though the pipes in the wall instead of backing up and eroding the wall away slowly.
Longevity and Stability
You want to build your wall to last, right? I know when I spend days building a retaining wall, I build it to last a lifetime and then some if possible. In order to get the best longevity out of a retainer wall, just follow all the recommendations given in this article and your wall is sure to outlast you!
Stability is perhaps the most overlooked concern when it comes to poorly designed retaining walls. I can’t count the number of walls I have seen that are leaning outward because of the stress of the earth pressing up against the back of the wall. There are several things you can do to make your wall more stable and to withstand the great pressure from several tons of soil and rock pressing up against its backside constantly.
While you may not need to use all of the methods discussed here, you surely have to choose the proper method for your situation and resources available to you. Stability is perhaps the most important consideration while building your wall. Below, in the instructions for building a wall, you will find several methods that can be used to increase the walls stability and ability to hold back vast amounts of land.
Methods used to keep the wall from leaning include rebar ran though the centers of the blocks and filling the blocks with cement. Another stabilizing technique commonly used is stepping your wall backwards into the hill that is being retained. Sometimes just stepping each row of blocks back one inch or so will greatly increase its ability to hold the earth back successfully.
Another great method for stabilizing your wall is to run beams back from the wall into the ground behind the wall at a slight downward angle. That is one of the most effective stabilizing methods used. When you run a beam from near the top of the wall, back into the ground behind it and cover it with fill dirt, that beam offers a great amount of restraining power and helps hold the wall in place and keeps it from leaning forward. You want the length of the beams to be at least the same height of the wall, but the longer the better within reason. Four by four beams are good for most cases, but you may choose to use either smaller or larger lumber or steel beams according to the size of your retaining wall and what it has to hold.
Another great determinant of a retaining wall’s stability is the walls foundation. You have to make sure the wall is built on solid, level ground. Commonly, you want to dig out the base of your wall to be about one foot deep and a bit wider than your blocks. You should have an L shaped foundation so your first course of block has a solid level bottom and rear side.
Ultimately you want a layer of fill dirt with about an inch of leveling sand on top for the surface to lay your first row of cinder blocks on. Below you can read the basic steps to building a basic retaining wall. Be sure to read the entire article though because you need to know more than just the below basic steps, you need all the information provided here to build a good retainer wall out of cement block.
Tools and Materials Required
Before you start this or any other project, you should make sure you have all the tools and materials gathered and ready to use. Here is a list of things you will need while building a cement retaining wall.
- -Shovel, picks, misc. digging equipment
-Cement bits and a drill (may be needed to drill holes for drainage pipes or running wire)
-Mixing bucket or cement mixer
-Fill dirt as needed
-Support beams (can be any material that is long enough and strong such as four by fours or steel posts)
-¾ inch PVC pipe or similar size for drainage at base of wall
-Rocks for surrounding the drain pipes
-Sledge hammer or equivalent to break blocks
-Pre-mixed cement mix
Basic Steps for Building a Cinder Block Retaining Wall
1. Build your foundation. Dig at least a foot down a bit wider than your blocks to start your foundation. Then use fill dirt and sand to make it sturdy and level as described above.
2. Many people like to have a full cement slab for a foundation. This is the best way. You pour a cement slab at least eight inches thick and set your rebar in it sticking straight up. The rebar will go through the hollow blocks when they are laid. The rebar should be L shaped with the bottom of the L buried in cement. The rebar should not go all the way though the cement because if it touches dirt, the rebar will erode over time.
3. Run your first row of block with the rebar going though the centers and up against the back inside of the blocks to help restrain the dirt that will press against the back of the wall when it is done. Fill the centers with cement and allow to set before continuing. You also need to install your drainage pipes while doing this first row of block. You will need to cut notches accordingly to allow the PVC pipes to pass though the wall. You should at least provide a pipe between every other block.
4. Continue running rows of block in that fashion until you reach the next to last row.
5. When you reach the next to last row, it is time to install your horizontal support beams to keep the wall from leaning forward over time as you see so often with retainer walls. Strategically, well placed support beams will prevent your wall from moving almost completely if it is done right. You may have to cut notches in the blocks to insert the beams though or sometimes you can run the beams in between the blocks. The method you use will depend on the type of beams you use. Make sure the beams are fastened securely to the wall going all the way though it for added support. In cases where it is permitted aesthetically, you can fix a large steel plate to the front of the wall and to the end of the beam to hold it firmly in place for years to come. You also want to be sure to use treated lumber if using wood for your support beams because untreated wood buried in the ground will rot incredibly fast.
6. Now, with your horizontal beams in place, lay your last one or two rows of cinder blocks to the top of the wall.
7. If you want to use a paint or sealer on the block, do so at this stage after the cement and mortar is well hardened. Fill in the area behind the wall with fill dirt and your job is done.
That’s all there is too it. While it may be a bit more complicated to build a good retaining wall than you thought at first, it is still a pretty simple project that most Do it yourself type people can handle with ease.