So, we’ve got this spot by the entrance to the new wood shop that needs a retaining wall. We had to dig the floor to the new wood shop down about 10 inches to make room for the concrete pad and the gravel bed under it. Also it was already 8 inches lower than the shop next to it. This left us with about 18 inches of hill that just can’t wait to slide in front of the door and block the way like a big dirt bouncer at a wood shop club. So we decided to build a railroad tie retaining wall to hold all the dirt back and guess what? We had a bunch of railroad ties laying around the farm. Perfect!
There are lots of methods to build railroad tie retaining walls. Some people do it this way, some people do it that way… this is the way we did it. If you do it a different way, good for you! Go tell your mom about it and hang it up on the fridge. Just kidding, tell us about it, we like to learn new methods too!
First, we leveled the area where to wall was going to be. Actually, it is slightly sloping down away from the building. We then tamped the dirt to make a nice, hard foundation. Tamping the dirt will also help to minimize settling and shifting of the wall. Although, it will settle and shift a bit no matter what you do.
You want to cut the area where the wall will be square so the ties fit in there nicely. Make the area about 5 or 6 inches deeper than the railroad ties so you have room to fill the area behind the tie wall with gravel. This will allow any water coming down the hill to seep into the gravel instead of bulging out your tie wall and eventually making it fall down, or move around and piss you off.
Once you’ve got a good area for your wall made, put down a foundational layer of gravel. We did ours about 4 inches thick and tamped it down real good. This will provide bottom drainage for the wall, allowing the water to drain away through the gravel instead of pushing the railroad ties out or eroding the dirt away from the wall.
Once you have a good bed of gravel laid down and tamped, it’s time to level the first tie in the wall. It’s important to get this tie as level as possible because any error will be compounded the higher the wall is. Take away or add gravel underneath the tie as needed until it is level in both directions. Having the wall out of plumb will also cause the wall to sag, bulge or fall faster. Using a sledgehammer as a tamper works pretty well to tamp gravel under the front or back edge to adjust it.
Next, you’re gonna need to make some pins or “dead men” as Greg from the Cassilly Crew and many others likes to call them. Most people use rebar because the ridges help to grab the dirt and railroad ties to hold the wall solid. We didn’t have much rebar on hand but we did have these square bent 1/2″ steel rod things with eyelets on the end we found in the barn. So we just chopped those up.
The first set of pins that are going through the bottom tie are very important. These will pin the wall firmly to the ground. Our wall was 8 feet long, so we used 4 pins. Each of the pins should be about 2-2 1/2 feet long so that you get a good solid hold into the ground.
If you cut one end at an angle, it will be a lot easier to drive the pin through the soil or through the railroad tie. Sometimes it can be near impossible to get a pin through a railroad tie without cutting a point on it.
Now you gotta drill some holes. You want the hole to be the same size or just slightly bigger than the pin you are going to drive through it. You can drill it smaller if you want, but it will make pounding the pin in a real pain. Especially if your pins are made out of rebar. I guess if you really wanted to prove you are a big strong man, you could probably just drive the pin straight through the tie without pre-drilling. But to hell with all of that! It’ll probably just get all bent up anyway. Pre-drilling a pilot hole is the way to go.
The best thing to use is a long wood auger bit as opposed to one of those drill bit extender things. The drill bit extender will probably work, however, it will also probably come loose in one of the railroad ties at some point. Thus creating a permanent home for one of your drill bits inside one of the ties. Drill bit extenders are pretty cool but not for this application. Railroad ties are made of tough oak and are soaked in tar and baked in. They’re pretty tough. An auger bit will eat right through it and has the length to drill through more than one tie at a time when need be. Try not to hit the ground too much or your bit will go dull real fast.
Lastly and obviously, use a corded drill that has some power. If you try to dive an auger bit into a railroad tie with a rinky dinky cordless drill, neither you nor the drill (nor its battery) will be happy.
Now it’s time to pound in some pins. We like to start them off with a 5 lb hand sledge and finish them off with a 10 lb full sledge hammer when the goin’ gets tough. Once you’ve got the pin almost all the way in and there’s about 4-5 inches sticking up, pound it over to lock the railroad tie down so it can’t slide off the pin. Since our wall is 8 feet long, we put a pin in about every 2 feet or so. We wanted to make sure that the foundation tie was really secured to the ground well.
After the pins in the first tie are set, fill that 5-6 inch gap between the back of the tie and the hill that it will be holding back with gravel. Tamp it down with a sledge hammer. We like to put down about 2-3 inches of gravel at a time and then tamp it, and then add another 2-3 inches, tamp it and so on and so forth.
A chainsaw works great for cutting railroad ties. However, BE CAREFUL!! Not just the normal using a chainsaw be careful, but be careful of all the nails, screws, plates and other strange miscellaneous metal crap that loves to hide inside of railroad ties and destroy chainsaw chains. Make sure to examine the spot where you are going to be cutting and look for signs that anything metal might have been driven in there. Shooting a bunch of sparks and busting the teeth off of a chain sucks! The best way to remember to check your cut path for metal is to forget to do it and hit something one time. No fun.
Now just repeat the process. Place a railroad tie on top of the last tie you laid, drill into it and the one below it as deep as you can, drive in the pins, fill the back side with gravel, tamp it down and repeat!
It’s ok to cover everything up with dirt if that’s the look you’re going for. It should not affect drainage too much. We did it only temporarily until we get around to filling this whole area in with gravel driveway and connecting it to the rest of our driveway. When that day comes, we will remove the little bit of dirt that is covering the gravel between the ties and the wall to allow for even better drainage. This is also why it look like the dirt is a little low. Gotta leave room for gravel driveway!
Good luck with your railroad tie retaining wall!