Radial Hand-Cleaving (Spalten) & Drawknife Tapering in Bregenzerwald Shingles

To understand why traditional Bregenzerwald wood shingles outlast modern machine-milled siding by decades, one must examine wood at the microscopic cellular level. A coniferous tree trunk is composed of billions of elongated, hollow cellulose cells called tracheids, aligned parallel to the vertical axis of the tree. These microscopic conduits function during the tree’s life as pressurized pipelines transporting water and minerals from roots to canopy.

When wood is cut with a mechanical circular saw or band saw, the spinning steel teeth slice indifferently across these cellular conduits at arbitrary angles, severing millions of tube walls and exposing open capillary lumens to the atmosphere. When rain strikes a sawn shingle, these severed tubes act like micro-drinking straws, sucking water deep into the core via capillary action. In sharp contrast, radial hand-cleaving (Spalten) applies mechanical wedge tension that forces the wood to split along the path of least resistance—parting the cells along their natural intercellular middle lamella without fracturing the cell walls. The resulting cleft surface presents an unbroken, continuous armor of intact cellulose fibers that sheds water instantly.

The artisanal splitting of shingle bolts is performed using specialized, hand-forged tools unchanged since the Middle Ages. The central instrument is the Spalteisen (froe), a heavy carbon-steel blade measuring roughly 350 mm in length, with a blunt, robust spine and an eye forged at one end to receive an upright ash-wood handle. The craftsman places the edge of the froe across the top end-grain of the shingle bolt, aligned strictly along the radial plane from pith to bark.

Using a heavy cylindrical wooden mallet turned from dense European hornbeam or beech (the Schlägel), the shingle maker strikes the spine of the froe to seat the blade 20 mm into the end grain. The mallet is then set aside, and the long wooden handle is grasped with both hands. By pushing and pulling the handle, the craftsman leverages the blade like a crowbar. This rotational torque tears the wood open along its radial medullary rays, propagating a clean, straight split from top to bottom in a fraction of a second.

A freshly cleft shingle blank is relatively thick (10 to 12 mm) and parallel-sided. If nailed to a wall in this state, the overlapping courses would kick outward awkwardly, creating wide voids that catch wind-driven rain and snow. To ensure a tight, planar, weather-tight lap, the shingle must be tapered along its length. This delicate shaping is performed on a traditional foot-operated clamping bench called the Schnitzbank (shaving horse, or Hoazelbank).

The artisan sits astride the wooden bench, resting their feet upon a pivoting wooden swing-frame. Depressing the foot pedal swings a heavy wooden clamping head forward, pinning the cleft shingle securely against the angled worktable with hundreds of pounds of mechanical force. With both hands free, the craftsman takes the Ziehmesser (drawknife)—a curved, razor-sharp two-handled blade—and draws it smoothly toward their chest. In three or four practiced, sweeping passes, the upper two-thirds of the shingle is tapered down to a feather-thin head of just 2 to 3 mm, while the bottom butt is left at its full structural thickness of 8 to 10 mm to face the weather.

Quality control in Bregenzerwald shingle making is uncompromising. As each shingle is shaved, the craftsman assesses its grain alignment, flexibility, and fiber density. Shingles are sorted into three distinct structural grades: First-Grade Standing Ring (vertical grain oriented strictly 90° to the face), Second-Grade Semi-Radial, and Utility Grade.

Only first-grade standing-ring shingles are selected for exterior wall facades and high-exposure roof slopes. Standing-ring wood exhibits virtually zero tangential shrinkage, eliminating the risk of cupping, warping, or lateral splitting under extreme alpine temperature swings. Second-grade shingles are reserved for sheltered soffits, gable under-eaves, and agricultural barns. Shingles that fail inspection are immediately set aside for kindling; in the rigorous ethic of Vorarlberg craftsmanship, a single flawed shingle could compromise an entire wall intended to endure for a century.