# Forum Home Renovation Retaining Walls  Adding height to concrete retaining wall with keystone

## bikerbabcock

I am leveling some terracing in my back yard and to do that I need to add to the current concrete retaining wall system. I am planning on using stone gate contemporary block. I want to place the block directly behind the existing concrete wall which is 24 inches tall and put in my block to a total wall height of 46 inches. Am I going to have any surcharge problems to contend with or will the concrete wall be able to hold the additional weight?

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## droog

If the top wall is located beyond the zone of influence from the bottom wall it has no impact, otherwise you need to know the engineering specs on the bottom foundation.

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## BIM

If the second retaining wall is placed directly behind the front lower retaining wall
You will not be able to use the manufacturers details for the new wall
The wall will need to be certified by a licence Structural Engineer (PE)

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## Marc

The way to avoid that is to use gabion behind the top keystone wall rather than just fill.
As for certification ... the OP is in San Diego and we don't know the rules up there. My guess is that there are no rules  :Smilie:

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## BIM

There are rules in the US just like there are  here in OZ
Falsify Engineering Stamps/ drawings  you might end up in jail https://www.wsfa.com/story/32350914/...afe-buildings/

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