Landscaping Timbers – Use Railroad Ties to Build a Retaining Wall
Of all the ways to build a retaining wall, working with landscaping timbers or ”railroad ties” is certainly the easiest. It requires nowhere near the skill nor the actual physical effort involved in working with other alternatives such as stone, concrete block or brick.
Even so, the job has to be done correctly or you’ll discover that in a few years, the wall may begin to rot, shift, bulge or actually topple under the pressure of the soil behind it. This is especially true in areas with lots of rainfall and freezing temperatures.
The technique described here works well for walls up to about 3 feet high. Beyond this height, it’s better to have the wall designed by an engineer or to have it built by a professional.
The ties, or landscaping timbers, come in a variety of sizes, but the best for walls are 5×5, 5×6 and 6×6. The 5×6 size is a good compromise. Laid on edge, it builds as fast as the 6×6 but costs less. Whatever size you choose, make sure it is pressure-treated with CCA. This treatment gives much greater rot protection than you’ll ever get in any other way. And CCA-treated wood will not harm nearby landscaping.
The cutting of timbers is best done with a chain saw. If you don’t have one, you can rent. It pays to get one bigger than you think you’ll need, and to make sure it is sharp. Dull, underpowered saws tend to bog down, wander and produce sloppy cuts.
Lay out your line of cut on the top, the face and the rear edge of the timber with a clear, dark line (I use a black felt marking pen). Then make your cut facing the rear of the timber. This will put any chipping and splintering of the back of the wall out of sight.
The foundation should be a firm base of packed soil or gravel, one full tie below ground level. This means you’ll have to dig a trench. If your soil is firm and drains well, dig about 6 inches; level and tamp firmly. If drainage or soft soil is a problem, dig down 1 foot; fill 6 inches with pea-size gravel and tamp down firmly. Make sure this base is firm and level.
Lay out your first course of ties, make sure they are firmly bedded and level, and then pin them to the ground for extra stability. The easiest way to do this is with 3-inch lengths of concrete reinforcing bar (rebar), sold at masonry supply houses. Prebore for these with a half-inch bit, about 20 inches from the ends of each tie, and then drive them in place with a sledge. Recheck for level and adjust as necessary.
The building now can begin in earnest. This is pretty much like playing with big, long blocks. Stagger all joints at least two feet, and overlap corners as shown in the sketch. Fasten each course to the one below it with 3/8-x-12-inch spikes. Space these 6 inches from the ends of each tie, and 24 inches apart along the length of each tie.
Whenever one tie overlaps a joint in the course below it, drive a pair of spikes down through the top tie into the two below, about 10 inches back from the joint. To prevent splitting, it’s a good idea to predrill with a quarter-inch bit, especially for spikes near the ends of timbers. This also makes it easier to drive the spikes home, and helps prevent them from wandering off course.
To help prevent the wall from bowing or tipping under the pressure of the earth behind it, you need some kind of anchoring device. If you can find earth anchors (long steel shafts with augers at the end), they are a good choice. Twist these two into the soil like a giant drill, and then fasten them to the ties with a pair of spikes driven into the eye at the other end.
Another alternative is to build a ”deadman” like the one in the sketch. Make this like a ”T” with a 40-inch stem and a 24-inch top. Spike it together and spike it to the wall, and bury it with firmly packed soil.
Whichever anchor you use, you’ll need one for every 8 feet of wall. Center it left to right and place it one course down from the top of the wall. Your wall also needs to be anchored at the ends. Normally you’ll do this by means of an intersecting wall as shown in the sketch. But if the retaining wall butts up against your foundation (as a driveway retaining wall often does), you can anchor that end of the wall with another deadman. In this case, tip the ”T” on edge so the top runs vertically instead of horizontally.
Technorati tags: wall youll ties soil inches timbers
No related posts.
Tags: landscaping timbers, railroad ties, repair retaining wall, retaining wall, retaining walls