How to Build a Stone Retaining Wall

Building a stone retaining wall can add beautiful hardscaping features to your landscape. Retaining walls prevent soil erosion, provide decorative borders and raised beds for plants and trees, and even create multi-level terraces for gardens. While constructing a retaining wall takes time and labor, doing it yourself with stone can save on costs compared to other building materials. With careful planning and preparation, you can create a stunning stone retaining wall.

Choose the Wall Location

The first step is deciding where to build the retaining wall on your property. Consider the following when selecting an optimal spot:

Purpose – Will the wall terraces be used for gardens, prevent erosion along a slope, or provide decoration? Determine the functional goals so the location best suits your needs.
Sunlight – Most plants require at least 6 hours of direct sun daily. If creating garden beds, be sure the location gets sufficient sunlight.
Drainage – Retaining walls need proper drainage so water does not pool behind the wall and cause structural damage. Choose a site that naturally slopes away from any structures.
Access – Pick a spot that allows delivery of materials and use of tools and equipment during the building process. The site should be easily accessible for future maintenance too.
Utilities – Avoid sites with buried pipes, wires, and other utilities. Call 811 for utility marking if needed.

Once you’ve determined the perfect place to build, you can start planning and preparing for construction.

Choose the Stone Type

Many types of natural stone work well for retaining walls, such as granite, limestone, and sandstone. Local quarries are often an affordable source. Avoid very porous stones that absorb water. Consider these factors when selecting stone:

Appearance – Match the aesthetic style you want to achieve. Limestone or sandstone often provide a more rustic look.
Weight – Heavier stones like granite are very stable. Lighter ones like limestone require a deeper footing.
Durability – Harder stones resist weathering. Softer sedimentary rock can deteriorate faster.
Texture – Smooth-faced stones are harder to stack. Stones with some natural texture provide stability.
Color – Variations in natural stone add visual interest. Blend different shades for a stacked stone look.
Cost – Using affordable local stone helps reduce the budget. Reclaimed stones can also lower material expenses.

Try to gather a sample of the stone type first to ensure it matches your retaining wall plans.

Plan the Wall Design

Now it’s time to map out the exact wall structure. Sketch the site layout and retaining wall placement, marking key dimensions.

Consider the total linear length and height. Building codes often limit home retaining walls to 4 feet tall before requiring extensive permitting. Terraced walls with multiple shorter levels are another option.

Determine the overall style – single-sided, double-sided, L-shaped, or curved walls all impact dimensions. Account for any slope by stepping up the wall height incrementally.

Calculate the square footage to estimate how much stone you will need. An average stone retaining wall requires about 15 stones per square foot. Add 10-15% for waste.

Lastly, plan where any drainage materials or pipes will go, marking subsurface water diversion if needed.

Prepare the Site

Proper site preparation sets the foundation for a structurally sound retaining wall that will resist shifting and settling. Here are key steps:

Mark layout – Use spray paint or stakes to mark the ground based on your plan.
excavate – Dig out the wall footprint to the correct depth and slope. Removing 8-12 inches is common.
Gravel base – Fill the excavated area with compacted gravel or crushed stone. This extended base reinforces stability.
Level – Use a transit or laser level to ensure the base is perfectly flat and sloped correctly.
Compact soil – The native soil behind the wall must be compacted thoroughly. This prevents settling later.

Take time on site prep because flaws at this stage can lead to ongoing issues with the finished wall.

Build a Solid Foundation

Constructing the stone retaining wall itself begins with the foundation. This anchors the entire structure. There are two main options:

Gravel Footing

A gravel footing provides a cost-effective base:

Dig a trench the width of the wall, 6-12 inches deep.
Fill with compacted gravel or crushed stone.
Level across the top surface.
The first course of stones rests directly on the footing.

Concrete Footing

For walls taller than 3 feet, a poured concrete footing adds reinforcement:

Dig a deeper trench, 12-24 inches below grade.
Pour a level 4-6 inch thick concrete pad.
Let the concrete fully cure for several days before stacking stones.

The concrete footing should extend 6 inches wider than the wall on each side. Steel rebar can also be added through the concrete to bolster the foundation.

Stack the Wall Stones

Now comes the labor-intensive process of actually stacking and arranging the stones. Follow these proven tips for success:

Level first course – Use a spirit level to ensure the bottom stones sit evenly.
Stagger seams – Avoid stacking stones vertically. Offset each layer like brickwork.
Largest stones on bottom – Maximize stability by placing bigger stones on the lower courses.
Fill gaps – Use small chipped stone to wedge into crevices for an even face.
Compacted backfill – Pack soil behind each layer before adding more.
Drainage – Incorporate perforated piping or gravel behind the wall to divert water.
Curve walls – Make gradual rounded turns, not sharp 90-degree angles.
Batter back – Slope the wall slightly toward the soil. A 1-inch batter per foot of height is standard.

Take the stacking process slowly, evaluating the wall face and backfill as you go. Having an extra set of hands helps too.

Finish the Wall Top

The coping or top finish completes your retaining wall structure:

Capstones – Large broad stones make an attractive cap. Through-stones overlapping the face look nice too.
Concrete – For a smooth flat top, pour a concrete cap at least 6 inches thick.
Gravel – A simple gravel top keeps costs down but won’t be decorative.
Drainage – Use drain tile, weep holes, or gravel to prevent water pooling.
Adhesive – Some situations require mortaring copings to the top courses or applying concrete adhesive.
Overhang – Don’t let the cap overhang too far. A slight beveled edge looks best.

Take time finishing the top according to your style, budget, and needs. The end of the wall should shed water and blend attractively into your landscape.

Backfill Behind the Wall

Once the retaining wall structure is complete, proper backfilling and grading prevents erosion:

Well-drained soil – Use a sand and gravel mixture without large rocks. Never backfill with clay.
Compact layers – Pack down soil in 6-8 inch layers as you backfill behind the wall.
Grading – Slope grade away from the wall at 1:6 ratio. Divert rainwater runoff.
No heavy equipment – Don’t drive heavy machinery near the wall; hand tools only.
Plantings – Wait until backfilling is done to plant close to the finished wall.
Weep holes – If using drain tile, cover the weep holes with gravel then 2-3 inches of soil.

Backfilling incrementally with the right soils ensures the wall stands securely. Taking shortcuts can compromise the structural integrity.

Maintaining Your Stone Retaining Wall

Regular maintenance keeps your hand-crafted stone wall looking great. Follow these upkeep tips:

Inspect annually – Check for bulges, cracks, soil washouts, plant overgrowth or other issues.
Re-level stones – Realign any stones that shifted over time. Reset caps as needed.
Control drainage – Keep weep holes, drainage pipes and gravel backfill clear of debris.
Limit vegetation – Prevent roots or woody plants from growing between stones.
Clean stones – Use a wire brush and mild soap to remove stains or algae on stones. Avoid pressure washing.
Repair cracks – Seal small cracks between stones with concrete epoxy filler. Larger issues may require rebuilding portions.
Watch for erosion – Refill and pack down any eroded soil. Shore up drainage areas.

With periodic maintenance, a properly built stone retaining wall can last decades and add enduring beauty to the landscape.

Frequently Asked Questions About Stone Retaining Walls

What tools do I need to build a stone retaining wall?

Masonry and digging tools like shovels, picks, trowels are needed. A 4-foot level, post pounder, wheelbarrow, stakes, and string line are also very useful. Safety gear like gloves, eye protection, boots, and possibly a dust mask should be worn.

What size stones are best?

Average stone size is often 6-8 inches thick by 12-18 inches wide and deep. Very large boulders take heavy equipment to move. Using a random mix of sizes adds character. Just be sure stones interlock well and don’t shift.

Should I mortar the stones together?

Mortar is not required in most freestanding walls under 4 feet tall. The weight of the stacked stones locks them together when properly constructed. Using mortar can actually prevent natural stone movement.

How deep should I make the gravel footing?

A typical gravel footing needs 6-12 inches depth depending on the wall height and soil conditions. More than 2 feet of stone may be required in poor soils. Extending the footing width 6-12 inches beyond the wall adds stability.

What slope should the finished wall have?

Retaining walls should have a slight slope or “batter” angling into the hillside. A 1 inch batter per foot of height is common. This allows natural soil pressure against the sloped backside.

Can I build a curved retaining wall?

Yes, curved walls can be created for added design flair but require more skill. Use smaller, wedge-shaped stones to build gradual curves. Tight 90 degree corners often lead to structural issues down the road.

Conclusion

Building a stone retaining wall takes planning, preparation, patience, and hard work. But the satisfying results are worth the effort. A hand-crafted stone wall makes a durable, decorative addition to any landscape. With a proper base, stone selection, compacted backfill, and good drainage, your wall can withstand the elements and provide beauty for generations. By maintaining your wall and making timely repairs, it will only look better with age. Your finished stone retaining wall becomes a lasting focal point to enjoy and take pride in.