So, you want to build a retaining wall: 6 things to know before you start

When you want to enhance your outdoor living space, consider building with retaining wall units. Segmental retaining wall (SRW) units are the basic building blocks of landscaping, and you will save on design and labor costs when you do it yourself. Whether you want to level a slope, build a sitting wall or add a raised patio, it’s essential to get informed before starting your project.

1. Check local rules. “Call 8-1-1 before you dig” is essential. Do-it-yourselfers also should check with their municipalities and homeowner’s associations for building codes, permits and/or property variance rules. Some municipalities require permits for walls up to four feet tall, although engineering might not be needed for that height with most SRW systems. A retaining wall taller than four feet might require geogrid for soil reinforcement and an approved design by a professional engineer. A landscaping supply store will know local permitting and can identify plans that might require an engineer.

2. Consider where you will buy supplies. A landscaping supply store is a great place to get educated, purchase landscaping products and rent tools such as a compactor. A dedicated landscaping store can help you choose which wall system is best suited to your project, calculate the materials you will need and offer advice before, during and after installation.

“Do-it-yourself customers are the foundation of who we serve at Patio Town stores,” said David Johnson, who manages one of Patio Town’s three locations in St. Paul/Minneapolis. “We have a team that will listen to what customers are thinking of doing, and then offer solutions and options. Should customers decide a project is more than they want to do, we can refer them to our design-build division, Villa Landscapes.”

3. Learn about retaining wall systems. Some systems are easier to install, and some require specialty pieces for corners, curves and steps. The VERSA-LOK Standard retaining wall system is easy to install, and no special pieces are needed to build features. VERSA-LOK Standard is a solid unit that is renowned for ease of installation as there are no voids in the unit to fill. Splitting the unit allows you to create curves, corners, columns, multi-angled corners, freestanding walls and steps.

4. Mark off, measure and photograph the project area. In addition to giving details about your project to your landscaping supplier, you might need advice to determine soil conditions or stormwater requirements. For example, clay soil retains water so it may need amendment, or the wall might require drainage pipes based on soil and other factors. You can discuss the content of your soil with landscaping store staff, who can offer ideas on remediation if needed.

5. It is all about the base. The base is the most important course. Retaining wall manufacturers and landscape suppliers can offer product-specific details on how to excavate and prep the base. After excavating a trench for the base, the subsoil should be compacted before a few inches of gravel is added and compacted. Make sure the area is level before starting the base course, which should be embedded half of the block’s height at a minimum. With solid units such as VERSA-LOK, there is no need for concrete footings as the base course serves as the foundation.

6. Finishing touches to consider. After each unit is placed and leveled, fill and compact the gravel placed behind the wall. Finish off your wall with capstone units that can be secured with adhesive; be sure your adhesive has elastic properties as modular walls are flexible so they can withstand freeze-thaw cycles.

Another important point to consider is the weather! Bad weather can hinder your installation. With a little planning, know-how and a trusted landscaping store that shares advice throughout your project, you can build successfully with retaining wall units.