How To Quickly Build A Durable Retaining Wall With 4x4 Posts

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So you want to build a retaining wall. We're all for it: they help hold soil at bay, keep water from flooding your flowerbeds, and boost your curb appeal. But many homeowners are turned off from building one because, at first glance, they look intimidating. The good news? You can build a sturdy, stylish one with some 4x4 wood posts.

4x4s are a favorite material to use to build a retaining wall because they're easier to lift and move (not to mention cut) than their 6x6 counterparts. Plus, this retaining wall material adds privacy and visual interest to nearly every landscape style. The trick is to use cedar or pressure-treated 4x4 wood. Even better, pick up posts that are treated for ground contact, like some 4x4 #2 Ground Contact Pressure-Treated Southern Yellow Pine Wood Posts. You'll also need some crushed stone or gravel for fill, and rebar or landscape spikes to keep the wall even and in place.

There are some downsides to using wood, primarily the risk of rot from poor drainage and wet soil, which is why adding drainage is important. If you install the wall properly, your wood retaining wall can last anywhere from 15 to 40 years. Install time will depend on how much prep you've done and how comfortable you are with DIY. More experienced folks may be able to build the wall in a weekend or less, while beginners may want to allocate a little more time to do it properly.

The most important tip for building a retaining wall is prep. The most important part of prep? Checking that there's no buried utility lines in your yard. Call 811 to check if it's safe to dig, then check with your local building inspector's office if you need a permit. Requirements vary by location. Some don't require a permit if your wall is under a certain height (typically 3 or 4 feet) and isn't supporting a heavy load. Next, don't forget to slather a preservative on the posts' cut ends before installing in order to reduce the chances of rot.

A common retaining wall mistake is forgetting to add a 4-inch drainage pipe behind the wall. It's worth the extra step. After any prep on drainage and the posts, clear the build site, then drill the boards that will lay at the bottom of the wall. Make a ½ inch or so hole about six inches from each end, then one in the middle for adding the rebar or spikes. Then, stage the crushed stone for the foundation and your preferred backfill (gravel is great), as well as the deadmen (boards that you install perpendicular behind the wall into the ground to support the weight of the soil) to make it easy to install.

Next, dig your trench, then layer in the crushed stone and compact. Once level, secure the bottom course (a.k.a., layer) of posts with 3-foot rebar. Build the wall course by course, securing with rebar or landscape spikes and making sure to stagger the ends to add strength to the wall. Continue building, adding deadmen every other row, until you reach the desired height, then backfill with gravel and tamp down.