Sheldonian Theatre Roof

This below was how the sheldonian originally looked.

Sheldonian theatre roof.

As you can see the roof was surrounded by oval windows. Wren designed a type of composite roof truss that was used instead although there is perhaps an echo of wallis s overlapping beams in some of the lead work in the windows. There is documentary evidence in wren s family papers that he had seen and admired wallis s design and that he seriously considered it for the roof of the sheldonian theatre. To do this without introducing loadbearing columns into the central space which would ruin the resemblance to an ancient theatre wren designed a roof truss able to span the required 70 feet a technical achievement which gained him great credit in scientific and architectural circles and made the roof of the sheldonian a landmark in roof construction.

Instead he decided to use the geometrical flat floor grid developed twenty years before by oxford professor john wallis. The sheldonian theatre is a spectacular design and well worth a visit go inside if no performance on to explore the majesty of the 8 cupola design and some nice views of oxford rooftops. Unfortunately it was never actually built. The original roof hailed as a masterpiece of architectural design is made up of a series of timber trusses and complicated cross beams supported by braces and screws without any columns.

This was partly because it was to house the oxford university press but the windows proved impractical and leaky and were removed in the 19th century. The design of the roof was due to john wallis the savilian professor of geometry. The span of the d shaped roof was over 70 feet 21 m. However no timbers existed that were long enough to cross that distance and wren dismissed the obvious solution of a gothic roof.