3' Retaining Wall Material Advice Needed

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Old 06-26-18, 01:42 PM
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3' Retaining Wall Material Advice Needed

Hi Everyone,

This is my first time posting and would appreciate some advice from some fellow DIY'ers.

The end of our backyard slopes down in some sections and in one area, the existing timber wood planks keeping the soil up are starting to rot away. I would like to put up a new retaining wall and expand the area a bit.

I have laid out posts to mark out area that I would like to expand to and the deepest the wall would be from the dirt to the current height is about 32". The total length of the wall will be about 25'.

My current plan is to bury 4x4 pressure treated timber posts every five feet, with 3' being above ground and 5' being below ground. Then I would stack 10' 2x6 pressure treated planks horizontally along the posts for the length of the wall. I would also tilt the posts into the slope 3". I will then place gravel and a french drain with landscaping fabric at the interior base of the wall.

I've seen many articles that use 6x6 beams that stack on top of each other and I am wondering if that is a better way to go? Or should I scrap the wood idea and use retaining wall blocks?

Thanks in advance for your advice!

Here are photos of the area.
 
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Old 06-26-18, 03:40 PM
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That's not the best plan. Your new wall will be holding back substantially more earth. 4x4" posts spaced 5' apart provides very little structure anchored into the soil to hold the wall in place. And, most 2"x lumber is not treated for ground contact so will likely have a short life.

I'm a fan of dry stacked, pre-cast concrete engineered retaining wall blocks. These are the larger commercial sized blocks that are engineered to be retaining wall blocks and not the smaller type found at most home centers. In your situation geogrid mesh would be required to further help hold the wall in place.

If you've just gotta go with wood posts and battens for your wall I would do some reading on "dead men". Those anchors buried uphill would help prevent your wall from being pushed over or from sliding down the hill.
 
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Old 06-26-18, 05:06 PM
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Thanks Dane,

So do you not think the 6x6 beams would be a good idea either? Below is a diagram of what I was thinking for that method, including using dead men.

I'm open to using blocks, I just thought wood would be easier to work with. Can you link me to the types of blocks and the size you are suggesting?
 
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Old 06-26-18, 05:48 PM
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wish I could find the pictures of my "Canyon" house where I installed 180 tons of bolders in my back yard, they are the ultimate material to use for slopes!
 
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Old 06-27-18, 06:03 AM
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Yes, something made of 6x6 would be better. But being wood it will have a limited life span. I would research precast concrete retaining wall systems.
 
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