A dry stone wall is not just a pile of stones stacked on top of one another, but a carefully designed engineering structure made of natural stone that can last for decades and centuries without a single gram of mortar. Building a dry stone wall combines craftsmanship with knowledge of materials and an understanding of the forces acting on a structure built on a slope. Those who understand the principles not only build a stable structure but also create one of the most valuable habitats that open-space planning can produce.
- What defines a dry stone wall and how it differs from mortar-bonded retaining walls
- Which stone materials are suitable and what to look for when selecting them
- How the foundation, slope, and layered structure function from a structural and engineering perspective
- Which design details determine stability and durability
- How backfill, drainage, and interlocking work together
- What ecological qualities distinguish dry stone walls in open spaces
- What common mistakes occur when building a dry stone wall and how to avoid them
- How dry stone walls are used in landscape architecture and public open spaces
Definition and Classification: What a dry stone wall is and what it must accomplish
A dry stone wall is a wall made of natural stone that is constructed without a binding agent—that is, without mortar, concrete, or cement. Its stability is derived exclusively from the stones’ own weight, their interlocking arrangement, and the frictional forces between the bearing surfaces. The term “dry” does not refer to the moisture content, but rather to the absence of mortar as a binding agent. In technical English, the structure is accordingly called a “dry stone wall,” and in French, a “mur en pierre sèche.” In 2018, UNESCO added the art of dry stone wall construction to the List of Intangible Cultural Heritage of Humanity, underscoring the cultural and historical significance of this building technique.
In open spaces, dry stone walls primarily serve a structural purpose: they support changes in terrain, stabilize slopes and terraces, and enable the use of sloped areas that would be too steep without support. In addition, they serve as space dividers, enclosures, or design elements in the landscape. Compared to mortar-bonded retaining walls, they have a decisive structural advantage: they are permeable to water. The water pressure that builds up behind an impermeable wall—and can lead to its failure—is largely eliminated in a dry stone wall because the water drains away through the joints. This property makes them a classic tool for nature-based water management on slopes.
In the context of landscape architecture and open-space planning, dry stone walls are not a niche solution but a versatile tool. They can be found in historic vineyards and orchards, in the Alpine and pre-Alpine cultural landscape, in 18th- and 19th-century parks, and in contemporary urban gardens and public open spaces. Their rediscovery in modern planning is not due to romantic nostalgia, but to an understanding of their ecological, design, and structural qualities.
Choice of Materials: Types of Stone, Properties, and Suitability
Choosing the right stone material when building a dry stone wall is not merely an aesthetic consideration, but a fundamental technical decision. Suitable stones are those that are compressive-strength, frost-resistant, and dimensionally stable—that is, they do not tend to splinter, flake, or swell when exposed to fluctuating moisture or frost. Soft, porous, or highly schistose stones are unsuitable for load-bearing dry stone walls. Sandstone with high compressive strength, limestone, granite, gneiss, basalt, porphyry, and various quartzites have proven to be effective. Slate is only suitable to a limited extent: Hard roofing slate can be used in flat layers, but if laid improperly, it tends to break along its cleavage planes.
The geometry of the stones is crucial for workability. Stones with as flat and parallel bearing surfaces as possible—that is, top and bottom surfaces—are ideal because they provide ample contact areas and distribute the load evenly. Quarry rubble—which is produced during blasting or crushing—often has a natural cleavage plane that can be used as a bearing surface. Field stones—that is, stones of glacial origin collected from the ground—are often rounded and require more skill when laying them, because the contact surfaces are smaller and more irregular. Cut stones with defined dimensions—known as ashlars or building stones—make constructing a dry stone wall considerably easier, but they are more expensive.
Regional availability is an important criterion for planning. Dry stone walls built from locally sourced stone not only blend aesthetically into the landscape but also significantly reduce transportation costs and, consequently, the structure’s environmental footprint. In planning practice, close coordination with regional quarries and natural stone suppliers is recommended to ensure quality, dimensional accuracy, and availability before construction begins. The amount of STEIN is typically specified in metric tons; for a dry stone wall of average thickness and height, a rough estimate is one to two metric tons of STEIN per square meter of wall surface, depending on the type of STEIN and the thickness of the layers.
Stone Sizes and Sorting
When constructing a dry stone wall, careful sorting of the material before construction begins is essential. Large, heavy stones belong in the lowest courses and in the foundation, as they form the base of the structure and bear the wall’s own weight. Medium-sized stones form the masonry of the middle courses. Small stones and gravel serve as filler material in the gaps and as backfill. Particularly long stones, known as “binders” or “spanners,” which span the full depth of the wall, are especially important for the stability of the bond and should be incorporated at regular intervals.
Structural Fundamentals: Foundation, Slope, and Layer Structure
Building a dry stone wall begins with the foundation, which transfers the entire load of the structure into the subsoil. For small walls up to about sixty centimeters in height, it is often sufficient to remove the topsoil and place a layer of large, flat STEINS directly on the natural ground. For taller walls or on subsoil with low bearing capacity, a foundation of crushed stone or gravel is required, which must be laid frost-free—that is, below the local frost line. In Central Europe, the frost line ranges between eighty and one hundred centimeters, depending on the region. A foundation that is not laid frost-free will shift in winter due to frost expansion, which destabilizes the wall over the long term.
The slope of the wall—that is, the angle of the wall’s surface relative to the vertical—is a key structural characteristic of every dry stone wall. Dry stone walls are always built with a slope, meaning the wall’s surface slopes slightly toward the supported slope. This slope, known in technical terms as the “setback,” ranges from five to fifteen percent depending on the wall height and stone material—that is, a setback of five to fifteen centimeters per meter of height. The slope ensures that the resultant force of the wall’s own weight and earth pressure runs as vertically as possible through the wall’s cross-section, preventing the wall from tipping forward. A dry stone wall built vertically is structurally much less stable and tends to shift when subjected to earth pressure or water pressure.
The layering structure follows the principle of masonry bonding: Each horizontal joint must be covered by the STEIN course above it. Vertical joints—that is, the vertical joints between adjacent STEINS—must not continue uninterrupted across multiple courses. This principle, known as cross-bond or running bond, is well-known in masonry construction and applies particularly to dry stone walls because no mortar seals the joints here, and the mechanical interlocking is the only means of force transmission. Each STEIN should rest on at least two STEINS in the layer below, and each joint should be covered by a STEIN in the next layer.
The wall depth—that is, the width of the wall’s cross-section—depends on the wall’s height. As a rule of thumb, the wall depth at the base should be at least one-third to one-half of the wall’s height. A wall one meter high therefore requires a base width of at least thirty to fifty centimeters. Taller walls require proportionally wider cross-sections. Double-shell dry stone walls, in which two outer rows of stones enclose a fill zone of smaller stone material, are better suited for greater heights than single-shell walls because they provide greater dead weight and a broader load distribution.
Backfill, Drainage, and the Physics of Earth Pressure
Behind every retaining wall, earth pressure builds up a horizontal force that tries to push the wall forward. With dry stone walls, water pressure adds a second, often underestimated load: If rainwater cannot drain away from the backfill area, the hydrostatic pressure behind the wall increases significantly. Building a dry stone wall therefore always involves careful planning of the backfill and drainage.
Well-draining, non-cohesive materials are suitable for backfill: gravel, crushed stone, recycled aggregate, or coarse-grained mineral mixtures. Cohesive soils—such as loam and clay—are unsuitable for backfill because they retain water, swell when wet, and freeze when exposed to frost. Both of these factors create increased pressure on the wall. In practice, a drainage layer of gravel or crushed stone is installed immediately behind the wall to channel water downward and allow it to escape through the wall’s joints. This drainage layer should be at least twenty to thirty centimeters thick and extend the full height of the wall.
Compaction is a critical factor when installing the backfill. Excessive compaction immediately behind the wall can displace the wall structure, which has not yet fully stabilized. The backfill should be added in layers using light equipment, starting from the bottom and working upward, parallel to the wall’s construction. This alternating process of building the wall and adding backfill in layers is one of the most important technical rules when constructing a dry stone wall and is often neglected by beginners.
Ecological Quality: Dry Stone Walls as Habitats
Dry stone walls are among the most species-rich structures that open spaces can produce. The open joints provide nesting sites for solitary wild bees and wasps, hiding places for lizards, slow worms, and grass snakes, as well as overwintering quarters for insects and spiders. The stone surfaces themselves serve as habitat for specialized lichen and moss communities that cannot survive on any other type of substrate. The thermal dynamics of a dry stone wall—heating up significantly during the day and cooling down rapidly at night—create a microclimate that attracts heat-loving species that can hardly find habitat in the typical landscape.
For open-space planning, this ecological quality is not a side effect but a planning objective. Dry stone walls are recognized as biotope structures in compensation and replacement measures under the Federal Nature Conservation Act and can be positively evaluated in impact-compensation assessments. A prerequisite is that they are built with suitable regional stone material and that the joints remain open—that is, they are not subsequently filled with mortar. Planting the joints with site-appropriate plants, such as stonecrop (Sedum species), wall rue (Asplenium ruta-muraria), wall ivy (Cymbalaria muralis), or stonecrop (Hylotelephium species), further enhances their ecological value but should not compromise the stability of the wall.
Particularly in the cultural landscape of Central Europe, historic dry stone walls in vineyards, orchard meadows, and terraced fields are relics of a form of land management that is rarely practiced today. Their preservation is not only a matter of historic preservation but also a conservation priority. Many landscape master plans and biotope surveys list dry stone walls as structures worthy of protection. For planning firms working in such cultural landscapes, knowledge of construction techniques and ecological requirements is therefore directly relevant to their practice.
Common Mistakes When Building a Dry Stone Wall and How to Avoid Them
The most common mistake when building a dry stone wall is placing stones with their long axis parallel to the wall’s surface without incorporating tie stones. Such walls look neat from the front, but they are not interlocked at depth and tend to split into separate sections that tilt independently of one another. Tie stones—that is, stones placed perpendicular to the wall’s surface and spanning the full depth of the wall—should be included at regular intervals, at least every one to two meters, in each course.
Another common mistake is laying STEINS with an outward slope—that is, so that the STEIN’s surface slopes away from the wall. Each STEIN should be laid with a slight inward slope so that water runs into the wall rather than down the front face. Steins that slope outward are undermined by frost and water and become loose over time. This rule applies especially to the top course of the wall, which is most exposed to the elements.
Using stones that are too small in the lower courses and stones that are too large at the top reverses the structural logic and destabilizes the structure. Equally problematic is the installation of stones that rest on only one point—so-called wobbly stones or tilting stones. Each STEIN must rest firmly on its base without tilting or wobbling. Small wedges made of hard gravel can be used to stabilize STEINS in the correct position, as long as they do not serve as the primary support. Mortar should generally be avoided as a stopgap solution for poorly seated STEINS, because it reduces the wall’s water permeability and leads to spalling in freezing conditions.
Finally, the wall crown—that is, the top course of the wall—is often neglected. A carefully laid cap course of flat, heavy STEINS, placed perpendicular to the wall’s surface, protects the underlying courses from erosion and provides the wall with its upper stability. An open, haphazard wall crown is the most common starting point for the gradual deterioration of a dry stone wall.
Dry Stone Walls in Landscape Architecture: Planning, Integration, and Maintenance
In professional open-space planning, the construction of a dry stone wall is both a design and an implementation issue. During the design phase, height, length, choice of materials, and integration into the topography determine the wall’s aesthetic impact. A dry stone wall made of regional limestone in a vineyard terrace setting conveys a different message than a granite wall in a contemporary city park. Both can be visually compelling if the material, proportions, and context are harmonious.
In the bidding and awarding process, dry stone walls are to be treated as natural stonework in accordance with VOB/C. The relevant standard is DIN 18332 (Natural Stonework), which, however, is primarily geared toward processed stone. In Germany, there is no separate DIN standard for dry stone wall construction in the strict sense; planning relies on technical literature, manufacturer recommendations, and the experience of specialized contractors. In Switzerland and France, there are more comprehensive technical guidelines and training standards for dry stone wall construction, which can also serve as a guide for German planning practices.
Maintenance of a dry stone wall is essentially limited to regular visual inspections and the repositioning of individual STEINS that have become loose due to frost, root pressure, or mechanical stress. Trees and shrubs with aggressive root systems, particularly black locust (Robinia pseudoacacia) and tree of heaven (Ailanthus altissima), should not be planted in the immediate vicinity of dry stone walls, as their roots can penetrate the joints and cause the wall to crack. Herbaceous plants and grasses growing in the joints, on the other hand, are not a problem and are ecologically desirable. A dry stone wall that is regularly inspected and repaired as needed can easily last for several generations.
Craftsmanship, Knowledge, and Responsibility: Building a Dry Stone Wall as a Planning Task
Building a dry stone wall is one of humanity’s oldest construction techniques and, at the same time, one that has unjustly become rare in contemporary landscape architecture and open-space planning. Its qualities are manifold: It is sustainable because it requires no energy-intensive binding agents and is fully dismantlable. It is ecologically valuable because it creates habitats that are rare in the natural landscape. It is visually striking because the natural material—STEIN—possesses an authenticity and materiality that no man-made product can replace. And it is technically robust when constructed according to the rules of the craft.
For design firms, this means that anyone integrating dry stone walls into projects needs expertise in structural engineering, soil mechanics, stone materials science, and craftsmanship. Collaborating with specialized contractors who have mastered the craft of dry stone wall construction is not a weakness but rather a mark of high-quality design. The number of specialized firms with proven expertise in dry stone wall construction is limited; involving them early in the planning process—ideally as early as the design phase—ensures quality and prevents construction errors that can hardly be corrected later without complete demolition.
The rediscovery of dry-stone wall construction in planning practice is not a step backward, but rather a return to a building technique that is particularly well-suited to the requirements of sustainable, biodiversity-promoting, and resource-conserving open-space design. Those who understand the principles of building a dry stone wall possess a tool capable of shaping the landscape, creating habitats, and leaving behind structures that are durable not in spite of, but because of, their simplicity.
