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The technique of fitting stones without mortar created structures that relied entirely on friction, gravity, and precise placement for stability. The advantages included not requiring mortar materials that might be scarce or expensive, the flexibility that allowed structure to shift slightly during earthquakes without catastrophic failure, and the ease of repair that allowed individual stones to be replaced without dismantling entire sections. The disadvantages were the greater skill required for adequate fitting and the necessity of using larger quantities of stone to achieve equivalent strength to mortared construction.
The foundation that provided stable base was even more critical for dry-stone than for mortared walls. The leveled surface that ensured stone courses were horizontal, the drainage that prevented water from undermining foundation, the selection of largest flattest stones for base courses—all contributed to creating stable foundation. The structure built on inadequate foundation would shift and potentially collapse regardless of how well upper courses were fitted.
The courses that built wall height layer by layer required careful placement to maintain stability. The overlapping that ensured vertical joints in one course didn’t align with those in courses above and below created interlocking that distributed loads. The use of through-stones that extended through wall thickness at regular intervals tied inner and outer faces together preventing separation. The gradual batter that made walls slightly narrower at top than at base increased stability by keeping center of gravity within footprint.
The capping that completed walls used largest flattest stones to create protective layer that shed water and prevented deterioration of courses below. The properly installed capping extended slightly beyond wall face, creating overhang that directed water away from wall. The maintenance that replaced displaced capping stones prevented water infiltration that could freeze and cause damage.
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