Rot resistance in landscape timbers...

generator12

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Hi everyone.

I've got a retaining wall made of landscape timbers backing up a flower berm. In three years the pressure-treated timbers have rotted badly. The wall still "retains" but I've got to replace it. The location is not conducive to the use of stone or blocks so I'm trying to determine the best wood or wood-like product to use.

Appearance is not an issue. This wall faces the house at a distance of about three feet, and its purpose is simply to hold back the dirt. So I don't care about color or fading. All I care about it rot resistance. As the pressure-treated hasn't stood up, I'm looking for an alternative.

As I understand it, the composites are wood and plastic mixes and have a "service life" for rot resistance. I have heard of plastic timbers but haven't seen them and don't currently know anyone who has used them.

Any suggestions?

Thanks in advance.
 

alldodge

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Old power poles or railroad ties. If you know someone with a lot of land and woods, see if you can cut down some cedar or locust trees
 

gm280

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Like AllDodge stated, rail road ties would be the better option. Try to get some that are in pretty good shape and install them with some long re-bar drilled down through them. That would do the trick.
 

jbcurt00

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Composite or plastic wood isnt very strong, I dont think it'd work very well.

Trex brand in 5.5in X 20ft is nearly like picking up a wet noodle in the summer w humidity in the Ohio Valley. If you picked it up in the middle, both ends touched the ground. Other brands (newer technology) may be better suited.....

Railroad ties are a good choice.....did you back tbe PT lumber w landscape cloth or put in a french drain to carry away water? The cloth lets water tbru but keeps dirty from getting between your PT planks which then holds moisture against them, speeding up rot.

Where are you?

In some places you can get 'better' PT treatment lumber. In California the 'best' was a particularly nasty to work w black PT lumber. But there was also a red, IIRC, that was only to mimic redwood, simply a different dye. And a blue that added an improved pest deterant. Plus generic green PT. Been nearly 15 yrs though...

If you end up going PT again, treat all the cut ends. Again, in California, we used a copper based product to treat all cut ends. It was a bright minty green.
 

sphelps

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There is always the option of pouring a concrete retaining wall .. How tall is it ?
 

minuteman62-64

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Not sure what you find in your area, but the stuff sold as landscape timbers here in the San Diego HD is cheap, but doesn't seem to be very rot resistant. If I'm putting wood in the ground I go to a lumber yard, and get something like 4x PT lumber, made for foundations.
 

dingbat

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Depends on where your located.

Around here, most of our "timbers" are yellow pine. Pretty rot resistant to begin with. Add pressure treat to them and they last a good while. The timbers on the stairs heading down to the pool went 20+ years before needing replaces.

The trick to a retaining wall is to keep moisture from building up behind them. A good drainage system (drain pipe and lots of gravel) is a must. The retaking walls surrounding the patio are still solid after almost 20 years
 

bigdee

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Jul 27, 2006
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Unfortunately PT lumber today is not very rot/insect resistant. The old CCA PT lumber would last years. I pulled up some old posts that had been in the ground for 50+ years and they looked new. Like others have said creosote railroad ties or powerline poles are probably your best bet.
 
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