An observation on the fan vault of Henry VII Chapel, Westminster

A close inspection was made of the vault of Henry VII Chapel, Westminster Abbey, when it was scaffolded for repair and maintenance in 1994–95. Defects were seen which appear to be peculiar to fan vaults, and this paper attempts to explain these defects. The discussion involves an understanding of the behaviour of masonry, from the simplest arch form to barrel vaults, rib vaults and the complex fan structure, with an examination of the ‘pathology’ of these forms.