Building the Retaining Wall Foundation

As you can see from the photo, I have begun laying the first course of retaining wall stones. This may seem like a straight-forward process, but it is, by far, one of the most important steps in building your wall. This is going to be one of the most time-consuming steps of the entire process, but don't get discouraged because the other rows will go up very quickly. You see, if the foundation is not prepared properly, your wall will eventually begin to sag and lose strength. So, by taking more time on this step, you can be assured of a wall that will last for many years to come.


What you will need...

Pea gravel
Tape measure
Wheel barrel
Shovel
Level
Hammer
Compacter (rented or hand tamper)
Cold chisel (to break stones in half)

What to do...


• Take pea gravel and add about 5 inches into the bottom of the trench


• Compact the gravel by using a compacter (which can be rented) or by using a heavy tamper


• Spray water on the compacted gravel (this will help the gravel settle)


• Compact again and measure


• Continue this process until you have 4 inches of compacted gravel


• Using a level, make sure that the gravel is level (This will speed-up the stone placement)


• Using a cold chisel, take one stone and break it in half ( Take the hammer and chisel and score the stone all the way around. At the back of the stone chisel harder until the stone breaks in half). You will than begin each alternating level with a half stone




• Why do this? You do not want the stones stacked with their edges lined-up, because this reduces the strength of the wall. You want the stones to be inter-connected, so we stagger the edges. This inter-connectedness is what gives the wall its strength. As the dirt pushes against the stones, it is trying to find a weak point. If the stones were installed with their edges lined-up, the dirt could push right through the gap and your wall would tumble down. When the stones are placed (as shown in this picture here) with their edges staggered, the dirt cannot find a place to push through, so your wall stays where it belongs




• Take a hammer and chisel and break-off the lip on your bottom stones


• Place the stone in the desired location and, using your torpedo level, make sure it is level from front to back and side to side


• Place second stone next to the first and make sure it is level from front to back and side to side; also make sure it is level to the stone next to it


• Repeat until all stones are placed

Just a quick note: unless you are very lucky, you probably run into problems. For example, I did not take into account the elevation change in our backyard. When the yard was originally landscaped, they graded the yard so the highest elevation is at the house and it then gradually gets lower as it nears the back fence. Now, if I was beginning the construction of my wall at the high-point, I would not have encountered a problem; however, as luck would have it, I started at the low point. So, in order to maintain my 4-inches of gravel, I soon discovered that I would have to dig a few inches deeper. Yes, it took a little longer, but I was able to maintain the integrity of the foundation. Problem solved.

You should also make sure that you have enough room for the lip of your second row of stones to fit between your first row of stones and the drainage pipe. (see picture below)



Again, there was about a 10-foot section of the trench that I needed to slightly enlarge. Not a big deal, but it was something unexpected.

I guess what I am trying to convey is: on a project this large, you WILL run into some problems. Don't get discouraged, but take a break and try and figure-out a solution. If you are not happy with how the stones are laying, don't be afraid to take them out and re-set them (Yes, I did this too). It may take a little longer now, but just keep in mind, you will be looking at this wall for many years. Isn't it better to take a little extra time now and get it just the way you want.

As I stated in an earlier article, this is being written as I build the wall, so it may be a few days before the next installment. The photo at the top of the page, shows my progress for today. Today went slower, because I had to figure out how to do the curve, but the straight runs will go much quicker. I hope that this has helped you get started with your new retaining wall. If you have any questions, please let me know and I will do my best to help you.


First in series... Planning Your Tiered Retaining Wall

Next in series... Building Your Retaining Wall: Finishing the First Row