Conical & Octagonal Brick Saracen Chimney Mitre Craftsmanship

Rising above the low-slung, tile-clad roofs of the Bresse plain, the mitre sarrasine (Saracen chimney mitre) is one of the most striking and enigmatic vernacular architectural forms in western Europe. While ordinary European farmhouses possessed modest, utilitarian masonry flues, the Bresse farmstead was crowned by a soaring, sculptural brick turret that resembled a miniature church belfry, an Islamic minaret, or a feudal watchtower. Over four hundred of these chimneys were documented in the 19th century across the Ain and Saône-et-Loire departments, with the highest concentration in communes such as Saint-Trivier-de-Courtes, Romenay, and Pont-de-Vaux.

The Romantic fascination with these structures led 19th-century antiquarians to attribute them to medieval Saracen conquerors or returning crusaders. However, rigorous architectural archaeology has demonstrated that the mitre evolved as a sophisticated response to vernacular heating and smoke-curing needs. Built primarily between the 16th and 18th centuries by local itinerant brickmasons (bousqueteurs), the mitre served as an outward emblem of agricultural prosperity and familial status while providing an aerodynamically flawless exhaust system for the four-sided open hearth below.

Constructing a heavy brick masonry turret atop a timber-framed roof presents formidable structural challenges. A typical octagonal Saracen mitre, standing between two and three meters tall, weighs between 800 and 1,500 kilograms. This concentrated dead load cannot rest on ordinary roof rafters; doing so would cause immediate roof collapse. Instead, master carpenters framed a specialized heavy-timber support system within the roof truss known as the chevêtre (trimmer).

The chevêtre consists of paired tie-beams and cross-timbers hewn from dense, seasoned pedunculate oak, with cross-sections measuring 20x25 to 25x30 centimeters. These trimmer beams are mortised directly into the primary roof trusses (fermes), transferring the vertical weight of the chimney downward into the interior load-bearing timber wall posts that divide the kitchen (chauffoir) from the threshing barn. Once the timber platform was locked with seasoned acacia pegs, it was covered with heavy lead sheeting and flat terracotta tiles, creating a fireproof, waterproof masonry bench upon which the bricklayer could lay the first courses of the mitre.

The construction of the mitre begins with a square brick base resting upon the timber trimmer. To transition from this square base to the elegant octagonal or circular shaft of the upper turret, the mason employs squinches (known in French masonry as trompes). Across the four interior corners of the square base, the bricklayer lays diagonal, corbelled courses of brick, creating four miniature triangular arches that bridge the corners. This geometric transformation creates an eight-sided perimeter that rises vertically to form the main chimney shaft.

The upper section of the mitre is designed as a belfry lantern. Here, the brickwork is punctured by four, six, or eight arched smoke discharge vents—the ouïes. These openings are framed by slender brick piers and crowned with semicircular arches formed from tapered bricks. The total open area of these vents is mathematically balanced: it must be large enough to allow the free escape of voluminous smoke from the open hearth below, yet sufficiently baffled to prevent sudden cross-winds from blowing into the flue. Above the belfry, the mason corbels the brick courses outward to form an overhanging dentil cornice, followed by an inward-stepping conical or pyramidal cap that sheds rainwater clear of the vent openings.

The aerodynamic and thermodynamic performance of the Saracen chimney is remarkably sophisticated. Because the hearth below is completely open on four sides, it produces an enormous volume of warm air mixed with wood smoke. As this thermal mass rises through the suspended timber hood in the attic, it accelerates into the narrower throat of the exterior brick mitre. The tapered shape of the turret acts as a natural thermal accelerator, increasing the velocity of the exhaust gases via the stack effect.

Crucially, the symmetrical belfry vents solve the universal flaw of historical open fireplaces: wind downdrafts. When gale-force Atlantic winds strike the Bresse roof, the air cannot blow straight down the chimney. Instead, wind entering a vent on the windward side passes horizontally through the belfry and exits through the leeward vents. This horizontal airflow generates a localized drop in atmospheric pressure within the chimney throat—a classic application of the Venturi principle—which actively pulls smoke upward from the hearth. To complete the structure, the summit is capped with a carved limestone finial and crowned with a wrought-iron cross or weathercock, which was grounded into the earth via an iron wire, serving as a vernacular lightning rod that protected the combustible timber-and-straw farmstead from disaster.