Dean’s Eye Rose Window, Lincoln Cathedral

The Dean’s Eye Rose Window was built in 1220 with a daring structural concept and unfortunately, but not surprisingly, started to fail not long thereafter. The tracery was beyond repair by the late 20th century and a replacement was required. Crucially the fabulous 13th century glass was still intact. As the window has a diameter of 7.5m, a thickness of 230mm and limited members this was no straightforward task.  As investigations progressed other difficulties such as instability of the North transept only added to the complexity of the task.

The final solution treated the window as three separate elements working together. The inner section of the window acting as a flat arch, with the central quatrefoil strengthened to carry the compressive loads and stiffened to resist deformation with a hoop tie introduced around the inner section to contain the outwards thrust from the flat arch. The outer roundels were designed to act as cantilevers projecting from the gable wall and taking only shear from the inner section. 

The selection of the materials to be used in the window was demanding. The criteria for stone included strength, durability, composition, bed depth, aesthetic considerations and ability to take fine carving. The search was arduous and, with no UK stone meeting a sufficient number of criteria, a French stone was found that was an acceptable compromise. The choice of metal was perhaps easier with titanium, phosphor bronze and stainless steel being considered, with a particular stainless steel with an electro-polished finish being the final choice.

The work on the reconstruction took place from 2003 to 2006 and cost £1.5m.  This was carried out by the cathedral’s own works department to a very high standard.

• Structural Engineering
• Conservation