# wood retaining wall help



## ron45 (Feb 25, 2014)

You should have done the upper wall first. Now all the excavation will come tumbling down on the lower wall. It's going to be difficult unless you have access from above.
Doesn't mean you can't make it work. The links below give some good advice, you will have to pick and choose what's going to work for your situation.

http://www.familyhandyman.com/landscaping/retaining-wall/how-to-build-a-retaining-wall/view-all











http://www.familyhandyman.com/lands...-build-a-treated-wood-retaining-wall/view-all


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## AndyGump (Sep 26, 2010)

I would not pile any more than about 18" of dirt and rock behind that.

By California code you are allowed to build a retaining wall 48" high without requiring engineering as measured from the bottom of the footing to the top of the wall. Most cities don't require a permit at about 3' high. That is assuming that there is no surcharge (slope) over about 1/5 behind it. But that is assuming a CMU wall with concrete footings. I believe San Diego has a standard diagram for a retaining wall on line.

Andy.


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## jeffboyardeee (Feb 15, 2015)

I planned to have it flat behind the wall. The total slope is about 10 feet deep and 62 inches high. This wall is already 30 inches high. Do you think I can attach a 4x4 or something behind the wall between the posts and anchor it back with a deadman to be able to go a little higher than the 18" you suggest. I probably should have done more research but kinda went off what a neighbor had done.


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## ron45 (Feb 25, 2014)

I take it you didn't click on the links and read it. There's pictures showing the process as well as the drainage.?


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## jeffboyardeee (Feb 15, 2015)

I did read it. My wall is completely different. There's not really a way to build the deadmans in that manner, because there's now no access to the vertical 4x4s from behind. So what I'm asking is for information and advice regarding the set up I already have. That's why I posted a picture. What I should have or could have done is irrelevant at this point.

any advice on building a dead men on this wall would be greatly appreciated.


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## Daniel Holzman (Mar 10, 2009)

I am not sure I fully understand your plan. You built one wall that is 30 inches tall. I think you are planning to build a second, 32 inch tall wall, possibly set back from the first one. Or maybe you want to build a second wall on top of the first one.

In any case, you asked about the need for dead men. A wall built with vertical posts and horizontal boards is known as soldier pile and lagging, where the soldier piles are the vertical 4x4's in your case, and the lagging are the 2x8's. It is possible to build tall walls using only solider pile and lagging, no deadmen, however as the wall gets taller the soldier piles need to be larger, and the lagging must be thicker. The required size of the pieces depends on what type of soil you have, the slope at the top of the wall, and how wet the soil can become. Wet soil exerts a lot more pressure on the wall than dry soil. So a properly designed soldier pile and lagging wall does not need dead men.

Dead men are typically horizontal supports that can be wood, steel, or occasionally special fabric, that are embedded in the soil behind the wall. Typically the minimum length of a deadman is about 2/3 the height of retained soil, so for a 5 foot tall wall, the deadmen would need to be a minimum of about 3 feet long at the bottom of the wall. Sometimes deadmen are fitted with metal plates on the end, so they grab more soil. Deadmen are used to support the soldier piles, and help to resist rotation of the soldier piles, which is usually how a wall fails. So if you use deadmen, you can use smaller soldier piles.

Deadmen are typically installed behind the wall before backfilling. However, if it is not possible to excavate, deadmen can be drilled into the soil using special equipment. Probably not a DIY option.

My suggestion is for you to discuss your project with the building inspector, who may have some personal experience installing a wall of your type with no deadmen. Unfortunately it can be pretty complicated to do the computations to size the solider piles and lagging, but for walls of around 5 feet tall such as the one you are describing, the building inspector may have a chart or similar tool to help you design and build. Or you could hire an engineer to assess the site and come up with some options.


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## jeffboyardeee (Feb 15, 2015)

Thank you Daniel that was very informative! My plan was to build the second wall about 9 or 10 feet behind this one, at a height of 32". Behind that that is level ground for about 12 to 15 feet. I will attach a picture taken before building the lower wall as a better visual.


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## ayjaymay (Mar 22, 2016)

Hi - How did your retaining wall project turn out? I'm looking at doing something similar. How deep did you bury your posts? How high did you end up going?


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## joed (Mar 13, 2005)

Looks like you are using those pound in 4x4 spikes. That is not good start.
If you want to keep the wall from tipping out you are going to need some deadmen to lock it back into the slope.
Here is an example










Note the cross bar on the anchor end.


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## Bondo (Dec 8, 2007)

Year old thread,....


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## jeffboyardeee (Feb 15, 2015)

Here are some pictures of how the wall looks now. The posts were dug 4ft deep. I painted the back of each 2x8 with asphalt emulsion and backfilled with 1/4 inch rock and rock from my never ending rock pile. I am in southern california so the weather is pretty mild. My soil is very rocky. Hope this helps you some with your project.


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## ayjaymay (Mar 22, 2016)

Thanks. Looks great! Great job.


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