Choosing Rocks for Building Stone Walls

Building a stone wall can add beauty and functionality to your landscape. Carefully selecting the right rocks is key to creating a structurally sound wall that will stand the test of time. When choosing rocks for your stone wall project, consider these factors:

Rock Type

The type of rock you choose impacts the overall look and durability of your wall. Some common rocks used for walls include:

Granite

Granite is an igneous rock known for its strength and durability. The coarse-grained texture and speckled appearance of granite can create a rustic, natural look. Granite is more expensive than other rocks but makes a good investment for walls requiring stability.

Limestone

Limestone has a softer, porous texture with a light color. Its natural chiseling ability makes limestone relatively easy to cut and shape for building. Limestone walls have an elegant, refined appearance but may deteriorate faster than harder rocks.

Sandstone

Sandstone is a sedimentary rock formed from compressed sand particles. The sandy texture gives it a distinctive layered, banded appearance in hues of red, brown, yellow, or grey. Sandstone shapes well but is moderately soft and prone to weathering.

Fieldstone

Fieldstone refers to loose stone gathered directly from fields or quarries. Composition varies, but fieldstone often consists of hardy igneous and metamorphic rocks like granite, quartzite, and slate. The irregular shapes make fieldstone walls appear old and rustic.

Manufactured Stone

Manufactured stone veneers offer an artificial alternative to natural stone. Made from concrete and colored with iron oxide pigments, manufactured stones mimic the look of natural stone for a fraction of the price. Use caution, as artificial stones may not withstand weather as well.

Stone Shape

The shape of your stones influences the structural stability and aesthetic of the wall:

Irregular or Rubble Stones: Smaller, irregular stones gathered from fields create a meandering, old-world look. Heartier rocks like granite and fieldstone are best for rumble walls. Mortar is often used to fill gaps.
Square Cut Stones: Machine-cut square stones have flat faces and square edges that allow tight fitting for stable walls. Softer sedimentary rocks like limestone and sandstone commonly get cut into blocks.
Rounded River Rocks: Naturally smooth, rounded river rocks stacked together form free-flowing organic walls. Use hardy igneous or metamorphic river rocks for better durability.
Flats or Flagstones: Flat flagstones work well for single-stacked walls and capstones. Their shape distributes weight evenly, enhancing structural integrity. Hard, dense rocks are best to withstand foot traffic.

Stone Size

Larger stones provide stability, while smaller rocks fill gaps and create a tighter fit. A general guideline is to use base rocks at least 2-3 times longer than tall for support. The chart below provides recommended minimum sizes based on wall height:

Use smaller filler rocks between large stones to wedge everything tightly together. In general, filler rocks should be less than 6 inches in diameter.

Weight and Density

Denser rocks have more weight and mass concentrated in a smaller volume, enhancing their durability as wall building material. Their weight helps keep walls firmly anchored. Some of the densest stone options include:

Granite: 167 lbs per cubic foot
Basalt: 163 lbs per cubic foot
Quartzite: 165 lbs per cubic foot
Limestone: 162 lbs per cubic foot
Sandstone: 144 lbs per cubic foot

Heavier rocks are also more challenging to move and work with during installation. Consider equipment needs when selecting high-density stone.

Lighter, porous stones like pumice (79 lbs per cubic foot) or scoria (70-80 lbs per cubic foot) are easier to handle but may not perform as well structurally.

Texture and Finish

The texture and finish of stone impacts its functionality, weather resistance, and aesthetics:

Rough, textured stones have more surface area for mortar adhesion and stability. Their uneven finish also hides flaws well. Use rough rocks for structural purposes.
Smooth, polished stones have a clean, refined finish. Carving, etching and staining show up better on smooth surfaces. Save polished stones for visible areas or decorative accents.
Non-porous granite and basalt resist weathering better than porous, water-absorbent rocks. Their durability makes them ideal for steps, edges, foundations, or areas exposed to moisture.
Softer sandstone develops an aged, timeworn look as it naturally erodes. Use sandstone if aiming for a distinguishing weathered character over time.

Color

The hues and color variations within stone create visual interest and texture. Consider how rock color impacts the overall look of your wall:

Monochromatic walls using a single rock type and color scheme exude cohesion. Popular monochromatic options include grey granite, tan limestone, or consistent fieldstone blends.
Contrasting colors paired together grab attention and highlight different design elements. Try integrating pockets of colored quartz or marble to contrast dominant wall colors.
Natural, earthy tones like beige, brown, taupe, and terracotta reflect organic elements. Earth-toned stone walls blend into natural surroundings.
Cool-toned stones in colors like blue, green, silver, or charcoal gray evoke a sleek, modern aesthetic. They pop against warm or neutral backdrops.
Warm-toned stones featuring red, orange, yellow, or pink hues exude heat. Warm colors feel energetic and complementary against cool greens and blues.

Cost

Price often dictates stone selection for walls. Some typical price ranges for wall stone include:

Fieldstone or rubble – $45-65 per ton
Limestone – $60-100 per ton
Granite – $130-180 per ton
Sandstone – $60-140 per ton
Manufactured stone veneers – $5-12 per square foot

Scour local quarries or stone suppliers for sales and overstock items to reduce costs. Factor cost per ton and delivery fees into your budget.

Sourcing Your Stone

Where you obtain stone impacts selection, cost, and convenience. Some options for sourcing wall stone include:

Local Quarries and Stone Yards

Quarries extract fresh stone from local deposits and are great for inspecting stones first-hand. Check for any quarry restrictions and arrange delivery ahead of time.

Construction Supply Centers

Retail locations allow you to see stone choices in person and cart away what you need. Inventory is limited, so order special items ahead.

Salvaged and Reclaimed Stone

Using recycled materials saves money and keeps useful stone out of landfills. Check laws, as some areas restrict gathering rocks from public properties.

Online Suppliers

Online shopping allows price comparisons and custom ordering. Ensure you can view photos or samples first, and account for shipping costs.

On-Site Gathering

Collecting fieldstone on your own property reduces costs. Evaluate safety and legality first, as trespassing laws may apply.

Synthetic Stone Alternatives

Manufactured and cultured stone provides uniformity and accessibility. While not authentic, it approximates the look of stone affordably.

Choosing Rocks for Specific Wall Sections

When collecting rocks, keep the unique structural needs of different wall sections in mind:

Foundation

The base bears the weight of the entire wall, so use the largest, heaviest stones here. Granite, basalt, or concrete footings provide solid bases.

Corners and Ends

Extra-large rocks with perpendicular flat faces anchor the corners and ends. Cut square-shaped stones also withstand lateral forces better than smaller irregular ones.

Filler Stones

Smaller rubble readily wedges between the gaps of larger rocks. Misshapen or irregular shaped fillers allow custom fitting. Softer rocks like limestone shape well as fillers.

Facings and Decorative Sections

Save the most decorative, colorful, or intricately patterned stones for visible sections. Use uniform pavers or mosaic designs for ornamental facings.

Capstones and Coping

Wide, flat rocks distribute weight evenly across the top of walls. Hard, dense flagstone capstones resist splintering or cracking underfoot.

Other Considerations

Keep the following factors in mind when collecting and preparing rock material:

Match stones structurally – Pair stronger stones with load-bearing tasks and softer rocks for fillers and decoration.
Evaluate faults or cracks – Scan rocks for existing cracks that compromise their integrity, especially if machine-cut.
Account for shaping – Natural, irregular stones require extra labor for squaring or smoothing.
Consider special tools – Very hard granites and basalts may need power tools for cutting or drilling holes.
Clean dirt and debris – Free rocks of soil, roots, and vegetation before incorporating them into walls.
Arrange delivery and storage – Carefully move heavy stones using proper equipment. Store rocks neatly to avoid losses.

Frequently Asked Questions About Choosing Rocks for Stone Walls

Several common questions arise when selecting rocks for building stone walls:

What is the best type of rock for durability?

Hard, dense igneous rocks like granite provide the best durability and weather resistance. Basalt and quartzite also withstand the elements well.

How much rock do I need for my project?

Total needs depend on wall dimensions, height, and thickness. As an estimate, every square foot of 3-foot high, 2-foot thick wall requires around 1/3 ton of stone. Wider or taller walls need more.

Should I use mortar with my stone wall?

Mortar adds stability but reduces flexibility. For freestanding landscape walls under 4 feet, you can skip mortar if you select interlocking shaped rocks and pack stones tightly. Use mortar for structural reinforcement or wet environments.

What is the ratio of large to small stones?

Aim for a 40/60 proportion. Around 40% of stones should consist of sizable rocks over 12 inches to anchor the wall structure. 60% of filler rocks 4-12 inches wide wedge between anchors and create an interlocking effect.

How much does an installed stone wall cost per square foot?

Total costs range between $25-$70 per square foot depending on materials, site conditions, labor, and wall height. Simple dry-stack fieldstone walls cost $25-$45 per square foot, while installed granite block walls run $60-$70 per square foot.

Conclusion

Choosing appropriate stone is vital for building robust, enduring stone walls suitable for your needs. Carefully evaluate the characteristics of different rocks, assess your site, determine priorities like aesthetics or budget, and collect a thoughtful variety of stone sizes, shapes, and types tailored for the project. Understanding how rock selection influences wall structure, appearance, longevity, and cost helps ensure your satisfaction from start to finish. With proper planning and preparation, you can feel confident assembling a quality stone wall that will gracefully withstand years of purpose and admiration.