Building a wood retaining wall with landscape timbers can be a tough job to handle on your own. However, as long as you use the right materials for the job and have this guide printed and ready by your side, you can never go wrong.
For a successful wood retaining wall construction, we’ve listed the materials that can help you ensure you’re building a wall that’s safe, good-looking, and can last a really long time.
Materials Needed:
- Excavation Equipment: Shovel, pickaxe, or backhoe for digging.
- Gravel: 3/4-inch crushed gravel for the foundation.
- Timbers: Pressure-treated wood is suitable for ground contact.
- Rebar: 3-foot lengths for securing the first course of timbers.
- Drainage Pipe: Perforated drain pipe for water management.
- Nonwoven Needle Punch Fabric: To wrap around the drainage pipe.
- Construction Screws: Boxes of 10’’ Strong-Drive® SDWS Structural Stainless Steel Screw (316 Grade)
- Tools:
- Hammer Drill: For driving rebar into the ground.
- Chainsaw: Small, 12-inch for cutting timber.
- Compact Equipment: To compress gravel in the foundation.
- Wood Preservative: For sealing cut ends of timbers to prevent decay.
- Drainage Stone: Washed 6A limestone for managing water drainage.
- Landscaping Fabric: To separate drainage stone from topsoil in finishing touches.
- Staples: For securing landscape fabric.
Permits and Regulations:
- Building Permit: Often required for retaining walls above a certain height (commonly over 4 feet). Check with local building codes.
- Zoning Permits: May be necessary depending on the location and purpose of the wall. Local zoning ordinances will have this information.
- Environmental Permits: If your construction impacts a place with environmental protections, like wetlands or important habitats, you might need extra permits.
- Utilities Clearance: Always check for underground utilities to prevent disruption and accidents.
Step-by-Step DIY Retaining Wall Wood Construction Guide
Step 1: Excavation
When building a wood retaining wall, begin by excavating the area for the retaining wall. You have to dig not just where the wall is going to be, but also a bit further back for the drainage stone and tiebacks. This will help hold the wall in place against the slope. The goal during this stage is to create a flat, level base and an area behind the wall for backfill and drainage.
Step 2: Lay the Foundation
A solid foundation ensures the stability of your retaining wall. Start by adding 6 to 8 inches of 3/4-inch crushed gravel in the trench. Compact the gravel thoroughly to create a stable base for your timber courses.
Step 3: Setting the First Course
Precisely laying the first course of timbers is crucial—the entire wall will stack upon it. Ensure the base level is completely flat and secure the timbers to the ground with 3-foot lengths of rebar, spaced approximately 2 feet apart. Pre-drill 1/2-inch holes into the timbers before driving the rebar into the ground.
Step 4: Wood Retaining Wall Drainage Installation
Drainage for retaining walls with timbers is paramount. Once there are a few courses, put the perforated drainpipe right against the back of the wall, on top of the gravel. Surround the pipe with nonwoven needle punch fabric to allow moisture to pass but prevent soil from clogging the drainage system.
Step 5: Fastening the Timbers
We recommend using Simpson Strong-Tie’s construction screws when building a wood retaining wall. They’re exterior-grade, and provide strong connections. Their flat washer head design lies flush with the timber surface without requiring pre-drilling. This adds to the aesthetics of your wall.
If you want wood retaining walls that can last a lifetime, use 316 grade stainless steel construction screws. These screws can cut your replacement costs tremendously over time.
Step 6: Build Structural Support (Deadmen)
To prevent your wall from leaning forward due to soil pressure, install tieback timbers, known as “deadmen.” Secure a timber perpendicular to the wall into the hillside and add a “T” section at the back using timber screws. These should be spaced every 8 feet and staggered vertically by 1 foot as you build higher.
Step 7: Cutting and Sealing Timbers
You’ll likely need to make cuts in the timber for a proper fit. A small 12-inch chainsaw is ideal for this task. After cutting, apply a wood preservative to the cut ends to prevent decay.
Step 8: Manage Water Drainage
Keeping water away from the wall is crucial. Lay fabric up the excavated slope and backfill the cavity with washed 6A limestone. This stone provides excellent drainage to channel water away from your wall, down to the perforated pipe, and out towards daylight.
Step 9: Finishing and Landscaping
Layer fabric over the top of the drainage stone two courses from the top, stapling it to the back of the wall. This creates a divider so you can add topsoil for planting without worrying about drainage contamination.
The Best Materials for Building a Retaining Wall from Wood
One big benefit of building a wood retaining wall on your own is the savings. You’ll be spending half of what you’ll spend on hiring wood retaining wall contractors. However, to make sure you’re actually saving some money, you need to use the best materials from the start.
The Best Wood for a Retaining Wall
The best wood to use for a retaining wall is pressure-treated wood. What makes most homeowners use this is the affordability and durability. The chemical treatment it goes through makes it suitable for structures that have contact with the ground or are exposed to moisture.
The Best Construction Screws for a Retaining Wall
The best construction fasteners are the Simpson Strong-Tie’s construction screws. Here are some ideas on how you can use them in building a retaining wall out of wood.
- Strong-Drive® SDWS Structural Stainless Steel Screw (316 Grade):
These provide a strong connection for heavy timber in wood-to-wood applications. This ensures a strong wood retaining wall.
- Simpson Strong-Drive® SD Connector Screws:
Coated for enhanced durability, ideal for connecting wood members and metal connectors.
- Strong-Drive Heavy Duty DWP Stainless Steel Screws (316 Grade):
Offers maximum corrosion resistance, perfect for exterior and marine environments.
- Strong-Drive® SDS Heavy Duty Hex Connector Screw (316 Grade):
Best for wood-to-wood structural connections, including landscape timbers.
- Strong-Drive® SDWC™ Truss Screw (Coated):
Great for wood-to-wood connections, such as attaching the upper parts of a retaining wall to posts.
- Strong-Drive® SDWH Timber-Hex Stainless Steel Screw (316 Grade):
Designed for landscape timbers and other applications requiring a hex-head drive.
- Strong-Drive® Stainless DWP Wood Screw (305 Grade):
A general-purpose screw for wood-to-wood connections where less corrosion resistance is needed.
The Best Way to Build a Wood Retaining Wall
With the right tools and a clear plan, there’s no doubt that you’ll build a wood retaining wall that is up to today’s standards. You won’t just be saving a lot of money. You will have complete control over the design, materials, and aesthetic appeal.
With this guide and with the list of the best materials, you’ll have a better chance in building a wood retaining wall that’s perfect for your family and property.
