Barrel and groin vault centering and voussoir laying represent the pinnacle of Majorcan stone masonry. Master stonecutters (picapedrers) erect rigid timber centering falsework (encimbrado) supported on adjustable hardwood folding wedges (falques). Trapezoidal marès voussoirs (dovelas) are cut with precise radial tapers and laid in symmetrical courses from opposing springing lines toward the apex. Bedded in thin joints of pure aerial lime mortar, the vault is locked into compression by driving a central keystone (clau de volta), after which the centering is gradually eased to mobilize compressive arch thrust.
At a Glance: Key Takeaways
- Vault Typologies: Volta de canó (barrel vault) and volta d'aresta (cross/groin vault)
- Masonry Unit: Dovelas (precision-dressed marès voussoirs with radial joint planes)
- Centering System: Encimbrado (timber trusses on timber posts with paired folding wedges)
- Mortar Composition: Pure aerial slaked lime putty (CL-90) and fine crushed marès sand (1:2 ratio)
- Decentering Window: 21 to 28 days post-closure to ensure adequate lime carbonation
Stereotomy and the Science of Vault Geometry
The construction of stone vaults in Majorcan architecture represents the highest expression of stereotomy—the mathematical science of cutting solids into three-dimensional architectural components. Unlike rough rubble masonry or brickwork, which accommodates geometric irregularities through mortar joints, dressed stone vaulting requires each marès block to function as an unyielding structural element within a rigid compressive system.
Master stonecutters (picapedrers) prepared for vaulting by drawing full-scale templates on the plaster floor of the workshop (sala de traçat). For a volta de canó (barrel vault), the geometry is cylindrical, requiring voussoirs (dovelas) with simple single-curvature tapers. For a volta d'aresta (groin vault), where two semicircular vaults intersect perpendicularly, the geometry becomes immensely complex. The stones along the diagonal groin lines (arestes) must be carved with compound curves and varying radial angles to ensure seamless continuity across intersecting spatial planes.
The Timber Encimbrado: Design and Falsework Engineering
A stone vault cannot exist in space until its final keystone is locked into place; until that precise moment, every individual voussoir is completely dependent upon temporary structural support. In Mallorca, this support is provided by the encimbrado—a robust timber falsework system engineered to bear the immense dead load of wet masonry without experiencing structural deflection.
The encimbrado consists of heavy timber arch trusses (cimbres) spaced at intervals of 80 to 120 centimeters along the vault axis. These trusses are constructed from dense Balearic pine or imported oak, rigidly braced with horizontal collar ties and diagonal king-posts. Across the upper curved profile of the trusses, carpenters nail narrow wooden laths or planks (taulons), creating a smooth, continuous timber cradle that matches the calculated intrados curve of the finished vault.
The Art of the Falques: Precision Decentering Mechanics
The most ingenious component of the Majorcan falsework system is deceptively simple: the falques (hardwood folding wedges). The vertical timber posts supporting the encimbrado do not rest directly on the ground; instead, each post sits atop a pair of opposing, finely planed oak or holm-oak wedges, lubricated with tallow or animal fat. During initial setup, driving the wedges inward raises the timber centering to its exact design elevation.
More importantly, the falques enable the safe, controlled striking of the centering (descimbrado). When the vault is complete and the lime mortar has attained sufficient compressive strength, workmen strike the narrow ends of the wedges with wooden mallets, backing them out in millimeter increments. This gradual lowering allows the stone vault to settle slowly under its own weight, gently closing any microscopic joint gaps and mobilizing compressive arch forces across the voussoirs without subjecting the green masonry to dangerous dynamic shocks.
Voussoir Laying, Mortar Dynamics, and Keystone Closure
Laying marès voussoirs is a rhythmic, highly disciplined operation. Because dry calcarenite exhibits intense capillary suction, masons thoroughly drench each dovela in clean lime water before setting. The bedding mortar is formulated from aged fat lime putty (cal aérea CL-90) and fine sand crushed from marès quarry waste, mixed in a 1:2 ratio. This produces a mortar with physical and thermal properties identical to the stone itself, ensuring uniform stress distribution and vapor breathability.
Masons advance the voussoir courses symmetrically from both springing walls toward the apex. As each ring nears completion, the master stonecutter prepares the clau de volta (keystone). Carved with a slight wedge taper on all four sides, the keystone is coated in rich lime slurry and driven firmly into the central apex opening using a heavy wooden beetle mallet. The resulting wedge action pre-stresses the entire arch ring, transforming independent stone blocks into a monolithic, self-supporting lithic membrane that can endure for centuries.
Structural Performance: Barrel Vaults (Volta de Canó) vs Groin Vaults (Volta d'Aresta)
Use this reference table to calculate exact physical dimensions, ratios, and specifications before purchasing:
| Structural Feature | Volta de Canó (Barrel Vault) | Volta d'Aresta (Groin Vault) | Catalan Timbrel Vault (Volta Catalana) |
|---|---|---|---|
| Thrust Distribution | Continuous linear outward thrust along two parallel walls | Concentrated point thrust directed onto four corner piers | Lightweight spatial thrust distributed to perimeter beams |
| Falsework Requirement | Full continuous timber centering (encimbrado complet) | Complex intersecting diagonal centering ribs | Formwork-free aerial laying; zero falsework required |
| Wall Openings Allowed | Limited; openings require relieving arches to preserve wall mass | Vast; perimeter walls can be completely opened with arches | Moderate; flexible adaptation across room bays |
| Stone Unit Thickness | 15 to 25 cm solid marès ashlar voussoirs | 15 to 22 cm dressed voussoirs along diagonal groins | 5 to 8 cm thin laminated terracotta tiles in gypsum |
| Acoustic & Thermal Mass | Exceptional acoustic resonance and high thermal inertia | Superb spatial volume with excellent natural ventilation | Low thermal mass; rapid thermal response to heating |
Practical Constraints
Every successful decoration project must account for physical and environmental constraints:
Slow Carbonation Rate of Aerial Lime Mortar inside Deep 20 cm Stone Joints
Lime requires atmospheric CO2 to harden; deep joints remain uncured and soft for weeks. Mitigation: Use dry, porous marès that allows air diffusion, keep joints thin (3–5 mm), and delay decentering for 28 days.
Outward Horizontal Thrust Vectors Spreading Supporting Masonry Walls
Lateral thrust pushes perimeter walls outward, opening hinge cracks along the vault intrados. Mitigation: Install heavy external buttresses or tie opposite wall plates with wrought iron tie rods (tirants de ferro).
Execution Blueprint & Craftsmanship Sequence
Execute this professional sequence to achieve flawless results without backtracking:
Springing Line Layout and Wall Ledge Dressing
Chisel a continuous inclined skewback ledge (arrencada) into the load-bearing stone walls at the calculated arch springing height, verifying absolute level with a water level.
Timber Centering Truss Fabrication (Cimbres)
Construct heavy timber centering arches (cimbres) from pine planks, matching the calculated vault curvature, and brace them with diagonal collar ties.
Centering Erection and Wedge Bedding (Falques)
Erect the centering trusses on vertical timber posts, placing pairs of greased hardwood folding wedges (falques) beneath each post to enable micro-controlled decentering.
Lathing the Centering Bed (Taulons)
Nail flexible timber laths or thin boards horizontally across the top of the centering trusses to create a continuous, smooth cylindrical surface to support the voussoirs.
Springing Course Laying (Primeres Doveles)
Dampen the stone springing ledges and bed the first course of marès voussoirs in pure aerial lime mortar, tapping them into position with a wooden mallet.
Symmetrical Incline Course Assembly
Advance the voussoir courses symmetrically from both walls toward the crown, using a radial string line anchored at the vault center of curvature to verify joint angles.
Keystone Ring Closure (Clau de Volta)
Coat the tapered sides of the central keystone with lime slurry and drive it firmly into the crown void, generating uniform compressive pre-stress across all voussoir rings.
Controlled Decentering and Striking (Descimbrado)
After 28 days of mortar curing, gently tap the hardwood folding wedges outward in small increments over three days, transferring vault dead load smoothly into compression.
Common Mistakes & Countermeasures
Avoid these costly errors that compromise aesthetics, ergonomics, and budget:
Laying voussoirs asymmetrically from one side of the vault to the other
Using thick, spongy mortar joints (>10 mm) between marès voussoirs
Striking the centering abruptly in a single rapid operation
Project Execution Checklist
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Frequently Asked Questions
How did Majorcan masons determine the exact taper of marès voussoirs?
Masons used full-scale layout drawings inscribed directly onto the plaster floor of the stonecutter's lodge (sala de traçat). Using a central pivot pin and a trammel rod set to the vault's radius, they drew the arch profile and divided it into an odd number of equal segments. From these lines, they fabricated rigid wooden or sheet-zinc bevel gauges (bauls) used to check the radial cuts on every voussoir.
What is the function of the falques (folding wedges) in centering falsework?
Falques are pairs of opposing hardwood wedges placed beneath each vertical timber post supporting the centering. During construction, they allow fine vertical leveling of the falsework. Once the vault is complete and the keystone is locked, tapping the wedges outward lowers the entire timber framework by fractions of a millimeter, transferring the vault's weight to the stone smoothly without dynamic impact.
Why must a stone vault always have an odd number of voussoirs?
An odd number of voussoirs ensures that there is a single, symmetrical keystone (clau de volta) at the exact apex of the arch. If an even number were used, a vertical mortar joint would sit at the crown—the precise location of maximum bending and shear stress—which would severely compromise the vault's structural integrity.
How are groin vaults (voltes d'aresta) constructed differently from barrel vaults?
In a groin vault, two barrel vaults intersect at right angles. The diagonal intersection lines form groins (arestes). Master masons must carve complex, compound-angled voussoirs along these groin lines, requiring two intersecting centering trusses. The groins concentrate all loads onto the four corner supports, requiring robust stone piers rather than continuous load-bearing walls.
