Wow , now that a comprehensive publication . If i can memorize all of that by midnight i want to be awarded a PHD .

 

I've yet to see PT reach the center of readily available 6x6's or even 4x4's. Any cross-cut reveals the penetration. Some do go deeper than others.

Perhaps you can special order deep treating, idk.

 

I've yet to see PT reach the center of readily available 6x6's or even 4x4's. Any cross-cut reveals the penetration. Some do go deeper than others.

Perhaps you can special order deep treating, idk.

u2slow, I'm sorry, I should have been clearer in what I was saying. What I was trying to say is that if the chemical treatment does not penetrate all the sapwood and reach the center.....meaning the heartwood, then you'll have more rot. But as you said, it won't penetrate the heartwood. The heartwood is too hard and dense for the treatment chemicals to penetrate. FYI, for anyone interested, I've attached the Southern Forest Products Association (SFPA) Marine Construction Guide which even though the focus is on marine environments, it's still a great resource for information on pressure-treated lumber and explains a lot of details about the different levels of treatment and their suitability.

 

Sounds good! The PR is my kind of place. Where do you live now?

 

You don't want to use railroad ties. Railroad ties are poor-quality wood and are treated with creosote or creosote borate. They will also rot out faster than pressure-treated timbers. You should use 6x6 pressure-treated timbers. Out west, they'll be doug fir (DF), and in most other places, it will be southern yellow pine (SYP). You'll want timbers treated for ground contact, but there are different levels of treatment. The labels on the end of the wood will specify the level of treatment. Chromium Copper Arsenate (CCA) was the most rot-resistant but is no longer used for residential applications except for higher rot-resistant embedded-in-ground support post applications and retaining walls. You won't find CCA at a big box store and you might not find it at a pro-yard, so you need to be specific as to what you're looking for when you're making phone calls. CCA treatment is great for retaining walls. The alternative to CCA to consider is MCA. Don't use ACQ lumber for a retaining wall if you want it to last. You want CCA or MCA. You want a UC4B treatment level (GROUND CONTACT, HEAVY DUTY) at the minimum, with UC4C (GROUND CONTACT, EXTREME DUTY) being preferable. Again, you won't find these treatment levels at big box stores. When you go to one of those stores and buy "ground contact" lumber, it's been treated to a UC4A spec (GROUND CONTACT, GENERAL) and will not last when used for a retaining wall. Here's a link to the AWPA (American Wood Protection Association) where you read some more about this. https://awpa.com/info/technical/homeowners It's worth spending the time and a bit more money to locate the proper timbers for your project so it will last a long time.

 

. You should use 6x6 pressure-treated timbers. Out west, they'll be doug fir (DF), and in most other places, it will be southern yellow pine (SYP). You'll want timbers treated for ground contact, but there are different levels of treatment.

Most treated wood out west here is spruce or balsam by a longshot. Doug fir is premium structural wood.

The batch of used PT 6x6's I got my hands on seem to rot in the center. Similar rot pattern with the RR ties.

 

Be careful with the fire. Cresote is not friendly and will burn your (or your neighbor's)lungs.

 

Agreed. RR tie disposal is a problem. The dump (mine anyway) won't take them either.

 

Dunno how long RR ties last, but mine are shot. Termites and ants are into them. Burn pile is next.

 

We use RR ties for posts for corral for cattle. Good ones are hard to get but if you keep looking you will eventually find some. We have a couple of corrals well over 100 years old and the RR tie posts are solid as can be.

 

I've seen a few around here that look very old but very sound. it must have been a branch line that was ripped up while the ties still had life in them. I would have thought the RRs would re-use for sidings, etc. Perhaps the landowner knew somebody or they were acquired through 'other means'.

Agreed. RR tie disposal is a problem. The dump (mine anyway) won't take them either.

The municipality here will take them but as landfill and you pay by the pound (well, kg actually). Railways used to burn them wayside back in the day. In some cases, the ones they don't flog to retailers are shredded and go to energy from waste co-generation plants where they can burned at extremely high temperatures.them

 

I can't find RR ties of decent condition anymore. Have resorted to old power poles and beach logs for coarse landscaping.

If spending money on on this, I would go with boulders or concrete block.

 

Some jurisdictions have legislated against RR ties because of creosote leaching. I don't know where one could acquired brand new ties, short of knowing somebody at a RR or one of their contractors, or perhaps a lonely siding, truck and flashlight.

Uses ties were replaced for a reason. They are heavy, can be full of grit and brutal on saw blades.

I'd go with the PT 6x6s, ground contact rated. Maybe not required at 3', but I would design in some tie-backs ('deadman'). I've seen a lot of short retaining walls that lean out over time.

 

I have done lot's with RR ties not bad id the junk has been sorted out or you can pick and choose. We used to get them for free and when we see them being sold there is a lot of crap in the pile.

 

Railroad ties have hollows in them that harbor yellow jackets by the kazillions. I would opt for a more solid wood like ground contact PT 6x6's with dead men occasionally.