Byloke Hospital: Interior, infirmary with trefoil-arched timber roof
Visible are the iron ties inserted ca. 1640 for stability.
The hospital (part of the former Cistercian abbey of Byloke or Bijloke) and its attached chapel form an L-shaped plan; the structures are joined by an integrated, twin-gabled façade at the west face. The chapel and a detached sick ward date from 14th to 16th century. The open-roofed infirmary of 11 bays is architecturally the most important timber structure at Byloke. The roof covers the ward (16 x 55 m). The masonry dates to 1228-1234 and occupies only 8 m of the overall height of 22 m. The walls (ca. 1 m thick) are buttressed at approximately 5 m intervals. Although considerable masonry support for the roof was designed, the walls have deflected outwards as a result of the combined roof thrust and shifting of the foundations; iron ties were inserted ca. 1640. The Byloke roof is a monumental two-tiered structure of steep pitch (ca. 60 degrees) forming a great trefoil arch. During an archaeological investigation of the site begun in 1990, the roof, whose date had been in question, was dated by dendrochronology with a felling date of AD 1251-1255.