Westminster Hall in the early 19th century

The restored new hammerbeam roof in the Great Hall at Stirling Castle.

Hammerbeam ceiling, carved in oak by Patrick Keely at St. Mary - St. Catherine of Siena Parish (Charlestown, MA).

Hammerbeam roof, in architecture, the name given to a Gothic open timber roof, of which the finest example is that over Westminster Hall (1395?1399).

In order to give greater height in the centre, the ordinary tie beam is cut through, and the portions remaining, known as hammerbeams, are supported by curved braces from the wall; in Westminster Hall, in order to give greater strength to the framing, a large arched piece of timber is carried across the hall, rising from the bottom of the wall piece to the centre of the collar beam, the latter being also supported by curved braces rising from the end of the hammer-beam.

The span of Westminster Hall is 68 ft. 4 in., and the opening between the ends of the hammer-beams 25 ft. 6 in. The height from the paving of the hall to the hammerbeam is 40 ft., and to the underside of the collar beam 63 ft. 6 in., so that an additional height in the centre of 23 ft. 6 in. has been gained.

It is believed that the widest hammerbeam roof in England at wide is in the train shed at Bristol Temple Meads railway station by Isambard Kingdom Brunel and Sir Matthew Digby Wyatt.^[1]

However, in actual fact, this roof at Bristol Temple Meads railway station uses modern cantilever construction, cleverly disguised, the hammerbeam style elements being purely decorative. The hammer posts and brackets support nothing, as all the weight of the roof is braced and supported by the massive side walls via the main timber ribs of the roof and the pillars inside the train shed.

Other important examples of hammerbeam roofs exist over the halls of Hampton Court and Eltham palaces, and there are numerous examples of smaller dimensions in churches throughout England and particularly in the eastern counties. The ends of the hammerbeams are usually decorated with winged angels holding shields; the curved braces and beams are richly moulded, and the spandrils in the larger examples filled in with tracery, as in Westminster Hall. Sometimes, but rarely, the collar beam is similarly treated, or cut through and supported by additional curved braces, as in the hall of the Middle Temple, London.

Recently, as part of an extensive restoration project undertaken by Historic Scotland, the hammerbeam roof of the Great Hall at Stirling Castle was completely renewed. Green oak from 350 Perthshire trees was used to fabricate and erect 57 hammerbeam trusses spanning approximately 15 metres. Since its construction around 1502 by King James IV of Scotland, structural loads from the roof had caused the walls of the hall to deflect outwards. To ensure that the ridge of the roof would be level and straight, the trusses were each made with a slightly different pitch and span. The restoration started in 1991 and was completed in 1999. http://cte.napier.ac.uk/what_timber.php

Other examples are in the Parliament Hall in Edinburgh and the Great Hall of Darnaway Castle in Moray.

References

de:Hammerbalken-Gewölbe simple:Hammerbeam roof