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sippinjoes 03-07-2011 02:54 PM

Retaining Wall Level Foundation
Tips and Tricks for leveling base of retaining wall:

I am about to take on a retaining wall project using gravity wall using their landscape stones. They have lots of good material and I am becoming well versed in the engineering that goes into the wall. I am inviting my dad to help me and only have him for a week. I have about 4 weeks worth of projects and want to make the most of my one week.

My Question: What are some tips you folks have for getting that first row level? Any jigs I can make or purchase before I start digging.

The wall is going to be almost 4 feet (permit height), so according to manufacture directions, I am going to have 1" base depth per foot of wall height. I am on Alabama soil (also know as hard clay), so I am comfortable with the minimum requirements, especially since my house is 50 years old and I'm sure the soil hasn't been touched. I would do some digging before hand, but my dad is bringing a backhoe to level my back yard and that will make quick work of my foundation trench and backfill area.



Kurtzilla 03-07-2011 03:47 PM

sippinjoes, make sure that you follow the proper excavation and base installation requirments for your wall. As for getting your first course / embedment block level, install a thin layer of stone dust or screens. This is refered to a choke course of material. It will allow you to set and level the first course easier. Make sure you level each block from front to back and side to side. Otherwise if your off, it will amplify as you go up with your wall.

sippinjoes 03-08-2011 08:38 AM


Are you saying to use "choke material" and then add #78 base stone? Further research has me thinking I will use a plate tamper (not a hand tamper) on the foundation SOIL and then add my 4" - 5" base stone #78 and tamp again. For patios, level is often achieved by setting PVC or some sort of pipe into the base (removing after it is level). Unless the community has any other ideas, I will be setting a level line just in front of the area for the base stone at the desired height. Once I think I am on that line and well compacted, I will set a level line where the top of the first row of stone will be and level each block (f/b and s/s) at that line. Can't seem to find any time saving tips for setting that first course other than to remain patient and do it right the first time.

sippinjoes 03-08-2011 02:19 PM

Site of my future retaining wall. Wall will follow Monkey Grass and the steps will be replaced.

concretemasonry 03-08-2011 03:04 PM

The 4" base thickness is a little skimpy, but could be O.K. - I accustomed to seeing much higher walls and on the engineered walls, the base course does not follow the simple 1" to 1' ratio and is much less and 8" or 12" is adequate for a 40'+ high wall.

The system you have chose does not have a shear resistance designed into the block like the more popular units, so the filling of cores should be adequate for a low wall and not too much extra material for filling cores is required.

To answer your question about leveling the first course, a mini backhoe with a good operator can do it himeself with little of no shovel work. Set enough accurate elevations along the wall location for excavation and take plenty of shots to maintain good elevation controls. You should use a plate compactor and can add a small amount of fines to the compacted base to make setting the bed course easier and more accurate. For the first course, set separate elevations at appropriate locations and run string lines pulled tight. For your curves, you will need more. Laya the first course as you describe and check periodically to see it is not wandering up or down because a short level is not good over a long distance. Be patient as you do the first course and then the rest of the courses will be many times faster and easier. Backfill with a well draining material.


sippinjoes 04-03-2011 09:01 PM

I have dug out for my foundation (side note: mini excavators are a blast to use). As suspected I ran into boulders, or rather one huge one. It is relatively flat across a 6 foot area of the foundation. My concern is that I have nothing in front of the boulder. So the foundation is pretty much the crushed gravel, some of which will be on a boulder, just laying out rather than in typical 2' wide trench. So, the first run won't be below ground level as it needs to be. Anyone had this situation before and have a solution? Thanks.

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