- Plan carefully before digging: Decide on the wall’s layout, consider drainage, and position it appropriately relative to your house to prevent future structural and water issues.
- Calculate materials accurately: Measure wall length and height, account for partial blocks, and purchase extra blocks and backfill materials to avoid interruptions during construction.
- Prepare a solid foundation: Excavate a level trench, compact the soil, and add a gravel or paver base to ensure the wall remains stable over time.
- Build step by step with stability in mind: Lay the first row level, stagger joints, add drainage gravel, and secure the top rows with adhesive for a strong, long-lasting wall.
- Regular maintenance is crucial: Inspect for shifting or damage, clear debris, refill settled soil or gravel, and monitor drainage systems to prevent problems.
- Enhance and protect the wall: Add decorative elements, plantings, or lighting, and maintain the surrounding landscape to improve aesthetics and prevent soil erosion.
Building a retaining wall can seem intimidating if you’ve never done it before. But the truth is, with the right guidance, materials, and a little patience, even a beginner can create a sturdy and attractive wall. In this guide, we’ll walk you through the process step by step, from planning and materials to construction and finishing touches.
Why Build a Retaining Wall?
Retaining walls are more than just a decorative feature in your yard. They serve several important functions:
- Prevent soil erosion: Keep your garden or lawn safe from water runoff.
- Manage slopes: Create flat surfaces on a hilly property for gardening or seating areas.
- Add visual appeal: A well-built wall can enhance your landscape design.
- Increase property value: A functional, attractive yard is always a plus for potential buyers.
Understanding the purpose of your wall will help guide the planning process.
What Tools and Materials Will You Need?
Before starting, gather all the tools and materials. Having everything on hand will make the project go smoothly.
Tools:
- Shovel and spade
- Level
- Tape measure
- Rubber mallet
- Wheelbarrow
- String line and stakes
- Trowel or masonry tools
Materials:
- Retaining wall blocks, stone, or timbers
- Gravel or crushed stone for drainage
- Paver base (for the foundation)
- Landscape fabric
- Concrete adhesive (for securing the top rows)
- Sand (optional, depending on block type)
Choosing materials suitable for your wall’s height and purpose ensures a strong, long-lasting structure.
How Do You Plan the Wall?
Careful planning is the foundation of a successful retaining wall. Skipping this step can lead to structural issues or a wall that doesn’t look right in your landscape.
Decide on the Layout
Begin by visualizing the shape of your wall. Freeform walls can curve naturally around garden beds, trees, or slopes, creating a soft, organic look. Straight walls, on the other hand, are easier to build and align. Use stakes and string to create straight lines, or flexible hoses to outline curves. Marking paint can help you visualize the final layout before you start digging.
Consider Drainage
Water is one of the biggest threats to retaining walls. Directing rainwater or downspouts toward the wall can cause soil behind the wall to shift, leading to leaning or collapse. Plan for water runoff by leaving a slight slope away from the wall or incorporating a drainage system with gravel and perforated pipe.
Placement Relative to Your House
Make sure the top of your wall is lower than your house’s siding to prevent water from pooling near your foundation. Also, consider how the wall will integrate with other landscape features, like patios, garden beds, or walkways.
Taking time at this stage will save headaches later, ensuring your wall is functional, safe, and visually pleasing.
How Do You Calculate Materials?
Accurately estimating materials prevents delays, extra trips to the store, or unfinished walls.
Length Calculations
Measure the total length of your wall and divide by the length of a single block to determine how many blocks you need per row. Don’t forget to round up, since partial blocks often require cutting.
Height Calculations
Divide the total wall height by the height of your chosen block to determine how many rows you will need. Taller walls may require additional support or reinforcement.
Extras to Account for Mistakes
Always buy 5–10% extra blocks to account for cutting errors, irregular terrain, or future repairs. This also gives you flexibility if you decide to extend the wall or add curves.
Other Materials
Don’t forget gravel for the base and drainage, landscape fabric, and concrete adhesive for the top rows. Calculating these ahead of time keeps the project moving smoothly.
How Do You Prepare the Ground?
A solid, level foundation is critical for a durable retaining wall. Skipping or rushing this step is the most common cause of wall failure.
Steps to Prepare the Base:
- Dig a trench: For most small walls, dig about 4–6 inches deep and 12 inches wide. The trench should follow the layout of your wall and be slightly wider than your blocks.
- Level and compact the soil: Use a tamper to compact the dirt at the bottom of the trench. A level base ensures the wall sits evenly and prevents leaning.
- Add a paver base: Spread about 3 inches of gravel or crushed stone. Compact it thoroughly, as this will support the weight of the wall and improve drainage.
Pro tip: Check the level in multiple directions to ensure a flat surface, especially if your yard has a slope.
Which Materials Are Best for Beginners?
Material choice impacts both the ease of construction and the durability of the wall:
- Concrete blocks: Lightweight, uniform, and easy to stack, making them ideal for beginners. Many blocks come with built-in interlocking features that simplify alignment.
- Timber: Good for low walls and budget-conscious projects, but less durable over time due to rot and insect damage. Pressure-treated wood is recommended if you choose this option.
- Natural stone: Offers a classic, high-end look but requires skill to fit pieces together. Irregular shapes can slow down the building process for beginners.
For most first-time builders, concrete blocks provide the best balance of ease, durability, and appearance.
How to Build a Retaining Wall Step by Step
Step 1: Lay the First Row
- Remove any locking flanges that prevent blocks from sitting flat.
- Start at the lowest point of your layout to work uphill, ensuring proper alignment.
- Use a level frequently. A single uneven block in the first row can throw off the entire wall.
Step 2: Stack Additional Rows
- Begin each new row with a half-cut block to stagger seams, increasing stability.
- Continue checking level and alignment as you stack.
- For higher walls, add gravel behind each row to reduce pressure from soil.
Step 3: Add Drainage
- Place landscape fabric behind the wall to prevent soil from mixing with gravel.
- Fill behind each row with gravel or crushed stone to provide proper drainage and reduce water pressure against the wall.
Step 4: Secure the Top Rows
- Apply concrete adhesive to the last two rows of full blocks.
- Press firmly to bond the blocks, ensuring a solid, finished top that won’t shift.
Step 5: Backfill and Finish
- Fold excess landscape fabric over the gravel to separate it from the soil.
- Backfill with soil behind the wall, creating a planting bed.
- Plant flowers, shrubs, or ground cover for both aesthetics and additional soil stabilization.
How Do You Ensure the Wall Stays Stable?
Maintaining stability involves careful attention to alignment, joints, and drainage:
- Always start with a level and compacted base.
- Stagger the joints between rows to distribute pressure evenly.
- Make sure drainage is consistent behind the wall; standing water can push blocks outward.
- Consider reinforcement such as geogrid for walls taller than 3 feet.
- Periodically check the wall during construction to ensure it’s straight and level.
Common Mistakes to Avoid
Even small errors can compromise a wall:
- Skipping base preparation or compacting the soil poorly.
- Ignoring drainage, leading to soil pressure buildup.
- Uneven or misaligned blocks that throw off subsequent rows.
- Choosing materials that are not suitable for the wall height or intended load.
How Long Will It Take?
Time depends on the wall size and your experience:
- Small walls (2–3 feet tall, under 20 feet long) can usually be completed in a weekend.
- Medium to large walls may require multiple days, especially when factoring in excavation, leveling, and backfilling.
- Rushing increases the risk of mistakes, so take breaks and double-check your work.
Can You Build a Wall on a Slope?
Yes, but it requires additional planning:
- Excavate in stepped levels to create a stable base for each section.
- Consider terracing for steeper slopes, creating multiple short walls instead of one tall wall.
- Ensure drainage at each level to prevent soil erosion and pressure buildup.
How Do You Maintain Your Retaining Wall?
Maintaining your retaining wall is just as important as building it. Regular maintenance ensures the wall stays safe, stable, and visually appealing for years. Even a well-built wall can develop issues over time due to weather, soil movement, or plant growth, so taking proactive steps can prevent costly repairs.
1. Inspect for Leaning, Cracks, or Loose Blocks
- Perform a visual inspection every few months, especially after heavy rains or frost.
- Look for signs of shifting, such as blocks tilting forward, gaps forming between blocks, or cracking in concrete or stone.
- Use a level to check the top row occasionally; even a small lean can worsen over time.
- Early detection of problems allows you to fix issues before they compromise the entire wall’s stability.
2. Clear Debris and Vegetation Behind the Wall
- Remove leaves, sticks, and other debris that can trap moisture and cause soil to compact unevenly.
- Trim back roots from nearby trees and shrubs. Root growth behind a wall can push blocks outward and destabilize the structure.
- Avoid planting large trees too close to the wall unless you’ve planned for root barriers.
- Keep the area behind the wall clean and free-flowing to maintain proper drainage.
3. Refill Gravel or Soil if Settling Occurs
- Over time, the soil or gravel behind the wall may settle, creating gaps that reduce support.
- Add more gravel or soil as needed to maintain consistent backfill levels.
- Compact the new material carefully to prevent future settling.
- Check for water pooling behind the wall; if it’s occurring, you may need to improve drainage with additional gravel or a perforated pipe.
4. Secure or Replace Damaged Blocks Promptly
- Any cracked, broken, or loose blocks should be addressed immediately to prevent small problems from cascading into larger structural issues.
- Remove damaged blocks and replace them with new ones, ensuring they are level and properly aligned.
- If the top rows shift, apply concrete adhesive to secure them again.
- For walls built with natural stone, reposition stones and fill any gaps with small gravel or mortar depending on your wall type.
5. Monitor Drainage Systems
- Retaining walls rely heavily on drainage to prevent water pressure from pushing the wall outward.
- Inspect perforated pipes, gravel backfill, and weep holes for clogs or sediment buildup.
- Clean and flush drainage systems annually, especially after heavy storms.
- Proper drainage maintenance reduces the risk of leaning or collapsing walls.
6. Seasonal and Weather-Related Checks
- In winter, check for frost heave that may shift blocks, particularly in colder climates.
- After summer rains, inspect for soil erosion or washouts behind the wall.
- Seasonal inspections help you catch minor issues early, preventing major repairs later.
7. Maintain the Surrounding Landscape
- Mulch or plant ground cover along the front and top of the wall to reduce soil erosion and improve aesthetics.
- Avoid heavy machinery near the wall, which could disturb the base.
- Keep irrigation systems in check to prevent overwatering near the wall, which can weaken the soil behind it.
Pro Tip: Create a simple maintenance checklist with dates for inspections, drainage checks, and vegetation control. Even a small wall can benefit from a structured maintenance routine.
Enhancing Your Retaining Wall
Beyond functionality, retaining walls can be a design feature:
- Add capstones or decorative blocks for a polished look.
- Integrate plants along the wall or in planters for a natural finish.
- Use mulch or gravel to complement the surrounding landscape.
- Consider lighting along the wall to highlight the structure and improve safety.
Wrapping Up
Building a retaining wall might feel intimidating at first, but careful planning, proper material selection, and following a step-by-step process make it manageable for beginners. Remember to focus on the base, stagger the blocks, provide drainage, and secure the top rows. With patience and attention to detail, your wall can serve a practical purpose while adding beauty to your landscape for years to come.