Get matched with top retaining wall installation pros in Ettrick, WI

Yes, to build a retaining wall, a permit is required. Similarly, any repairs or modifications to an existing retaining wall require permits. If the planned wall measures higher than 4 feet, most municipalities require designs and permits come through a licensed engineer. In some locations, if the wall is shorter than 4 feet, a permit may not be required. For the requirements in your area, contact your local government.

Poured concrete is often the cheapest material for a retaining wall, costing around $6 to $8 per square foot. Other budget-friendly options include vinyl and landscaping timbers, which range from $10 to $15 per square foot; landscaping timbers are particularly well-suited for DIY projects. Untreated timber and railroad ties are a step up in price, starting at $15 to $25 per square foot. Natural stones can also be a cost-effective choice if you can source them from your own property, but they can be expensive to purchase. High-end materials like steel are typically the most expensive but offer superior durability and aesthetics.

Sand and gravel are two suitable options for filling behind a retaining wall. If you’re building your own retaining wall, you’ll complete this part of the process—known as backfilling—after you finish laying the blocks. Make sure not to skip it—otherwise, you could wind up with drainage issues, which can cause your retaining wall to collapse.

Railroad ties can be good for retaining walls, but it depends on the area. They have a desirable rustic look and are durable. The problem is they’re treated with creosote, a preservative the EPA says poses a risk to humans and wildlife. Over time, the preservative seeps out of the wood and into the ground. Many areas have banned the use of creosote-treated wood on residential properties. If your area does allow it, never use railroad ties near an edible garden or drinking water source. Instead, use wood that’s treated with an EPA-approved preservative or a wood-alternative composite material.