# How to start foundation for retaining wall, on a slope.



## bokeh (Nov 1, 2010)

Im trying to build a retaining wall and have a few questions. There was ivy there, but it didn't look good, so I removed it. Now I would like to build an elevated and level area to put grass. I've never done this before, if any additional info is needed, let me know.

I'll give you the picture first. the level line may be faint, so I put yellow areas at the starting points.










The driveway goes downhill in the area and that is the line I want to follow

I only want to build it a little higher than the base of the wall in the background, using the same type of blocks.

In the pic I have a pink line that is level, showing that on the right the wall will be higher than on the left. the line is close to the height I will be making the wall.

how deep should I dig for the walls foundation? say if the answer is 1 foot. should I start with a 1 foot depth at the low end then dig a level trench, making the high end a 3 foot trench when looking at it from the drive?

Im thinking that I will pour cement in the trench once I figure out how I should start. But Im not sure If the foundation should be poured before laying any blocks, or at the same time?

Do I need rebar in this wall?



thanks


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## mchipser (Sep 21, 2009)

You always want to start at the lowest level. I don't think you need to dig the high area down three feet.. Start at the lowest and dig down one block depth. Make sure to level the base and add the appropriate base, crushed rock? I am not sure how to explain the stepping that needs to be done, I will try and find it somewhere.


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## concretemasonry (Oct 10, 2006)

Do you plan on using block mortared together or the segmental retaining wall units?

Both are very common and the fifferent is in the footings.

A mortared wall is a rigid wall that requires a poured reinforced foundation. A segmental wall has very slight "batter" into the slope and uses no mortar and the foundation is compacted "gravel" and no concrete. On a sloped alignment, the wall is broken into segments and the lowest level of block is stepped. This concept is good for irregular surfaces and curved walls. If you are below 4 or 5' in height, no engineering is required, but it can go well beyond 20'. In other words, the ability to adapt to a site is the reason that the system is probably the most common method used.

Dick

Dick


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