# Building a Moss Rock retaining wall



## de-nagorg (Feb 23, 2014)

Could you explain this better. 

Copied from your post. 

I need to build 2 2ft high moss rock retaining walls 25 foot high for landcaping my front wall. 


I am not dense just confused.

ED


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## Daniel Holzman (Mar 10, 2009)

Perhaps the OPS had a typo, and means a 25 foot long retaining wall?

A dry stack rock retaining wall is in the class of retaining walls known as gravity walls, since the wall relies entirely on gravity and friction to stand up. For gravity walls, with a coefficient of friction of approximately 0.5 (typical for flat rocks), the wall needs to be a minimum of 40% as wide as it is tall in order to stand up to typical forces from retained soil. This is appropriate up to about 8 feet, beyond this height there are other factors that come into play, but for a two foot high wall, one foot wide would be sufficient. If the wall is truly 25 feet high, you are way out of bounds for normal dry stack technique, and need professional assistance.


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## rocketdoctor (Mar 18, 2009)

thanks for the reply yeah I made a type I was talking about 25 foot wall 2ft high. so roughly 1 foot wide is good enough? what type of base should I use?


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## Daniel Holzman (Mar 10, 2009)

A 2 foot high wall only needs a hard base, could be compacted soil if the soil is sandy or gravelly. If the soil is soft and weak, dig out a foot or so and replace with crushed stone, you will be fine.


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## rocketdoctor (Mar 18, 2009)

Another question, this wall is next to a drive way on a slope where the beginning of the driveway is a foot higher. do I need to start out with a level base, if so I would have alot or rock below the dirt line. Or is it possible to just dig a 6" trench the entire length of slope compact the dirt and set the stones in a manner that the top would meet a left string line at the 2ft mark. Seems this would save considerable time digging and cost of stones that would have to be entirely below ground.


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