For durable walls, tie them back into the hillside and provide good drainage Although a lot of contractors think poured concrete at the mention of retaining walls, I prefer wood. Whether you use new pressure-treated lumber or old railroad ties, timber walls are usually less expensive than concrete, simpler to build, blend well with other landscaping, and will last 25 years if constructed properly. Building low timber retaining walls is neither as hard nor as easy as many people think. It's true that you can't just spike a bunch of timbers together and expect them to stay in place. But you also don't need to go to the same
