Black locust and retaining wall

[OneStaple]

Hey all,

I'm finally getting some forward motion on getting my retaining wall redone ($$$$!). Planning to have someone else do the work, as it's too much for me to handle (9' x 70') on my own. Plan is to use the segmented concrete blocks for the bulk of the wall.

There's a little side area where the contractor speced out a couple tiers of railroad ties (each tier roughly 2' x 10') to reduce the grade. He suggested railroad ties to keep costs down, but my research suggests railroad ties area a bad and unhealthy option (and illegal even though sold in big box stores!), especially if our future kids might be playing in that area.

I'm looking into black locust as an alternative. I can get 6"x6"x10' boards a couple hours away and 4"x4"x10' boards closer (might also have 6x6), but all options are fairly green wood. My grandpa's property also has some black locust that I could cut down and have milled, but I haven't had a chance to check size/quantity.

They question is, is it ok to use green/wet black locust for the wall, or does it need to be dried first? All wood will have ground contact.

Thanks,
Tyler

[Bill Bob]

Ground contact not good for any wood unless pressure treated IMO. Have you thought of 8x8 treated timbers?
Bill

[jteneyck]

Black locust has been used for fence posts for generations. If they were dried I think it was just by chance, not by design. It should last 30+ years.

Excellent choice.

John

[JosephP]

You can use green Black locust.

But I am not sure RR ties are as evil as you suggest...

If you can find some old growth bald cypress, that is VERY rot resistant...but it has to be old growth, the more rapidly grown second growth is only moderately resistant to decay. Gonna be hard to find.

Longleaf pine heartwood is very good too...but unless you know it is longleaf, it is just marketed as SYP. I did an internship in coastal NC in 1997. We were doing some boundary line locations. The survey from 80+ years ago would say "corner marked with lightwood stake"...and we could still find those stakes! The old stumps would smell like fresh cut pine when you'd cut a chunk off.

Chestnut is too. Again, hard to find.

If they are replacing cedar utility poles, ask if you can have those. The cedar poles are often not treated. Again, they tend to be hard to get a hold of...there are plenty of these out there, but a lot of people want them. You might call the electric company to ask if they have any poles they are replacing and if you could have the old ones...then go look to see if they are untreated cedar or treated pine.

[mike4244]

50+ years ago I built and installed a picket fence for my aunt.I was told to use black locust if I can get it. I got black locust for the posts and cedar for the pickets.I still have relatives in the area and they told me the posts are still up.I was told the pickets have been replaced several times.My posts were green,I loaded into my truck as they came ff the saw.

mike

[OneStaple]

JosephP said:

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But I am not sure RR ties are as evil as you suggest...

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Thanks all for the thoughts. I guess if I'd thought through the concept of farmers using black locust for fence posts, I'd make sense that they used fresh cut wood.

Joseph, my impression of the railroad ties comes from reading a bunch of sources online. I can trust everything I read online, right? But even so, there's essentially nothing positive said about them. I usually try to ignore the obviously crazy or overdone opinions, but the quantity of condemning articles gives me pause for thought.

Some of those other rot resistant woods are going to be tough to source to, as you acknowledge. Not sure black locust will be any easier/harder. One plus for black locust is that it's also a very strong wood. But I'll certainly keep an eye out for other options.

Thanks,
Tyler

[GHR]

OneStaple said:

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There's a little side area where the contractor speced out a couple tiers of railroad ties (each tier roughly 2' x 10') to reduce the grade. He suggested railroad ties to keep costs down, but my research suggests railroad ties area a bad and unhealthy option (and illegal even though sold in big box stores!), especially if our future kids might be playing in that area.

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Concrete railroad ties.

[EdL]

In the past, I've had to tear out railroad tie landscaping as the morgage company wouldn't approve the loan with it there.

Ed

[mike4244]

Railroad ties are creosoted , probably why they are not recommended for residential use.
mike