‘Armchair’ voussoirs were constructional pieces used in creating the ribs of vaults in Roman buildings. Two graves found by NAA during the A1 upgrade included reused fragments of tufa armchair voussoirs in their lining. The rock is very soft and weathered, and the pieces are broken or battered, but where the surfaces survive well, the sawn edges are smooth. The original dimensions of the voussoirs were around 440mm long by 290mm wide. Most of the fragments from one grave have 15mm-thick mortar on at least one surface.

Such voussoirs were originally used in Roman bath buildings. They helped form a series of vault ribs, with cut-outs and notches supporting flat slabs between them. The presence of cut-outs at both the top and bottom show that the ribs supported upper and lower slabs to create hollow enclosures, which would allow warm air within the hypocaust heating system to circulate.

In Britain, the use of armchair voussoirs in bathhouses was generally a military practice. Examples in calcareous tufa are known from Chesters and Great Chesters, and in sandstone from Vindolanda and Wallsend. They appear to have been used as easy-to-construct kits for small vaults with a span of 3–5m, particularly during the 1st and 2nd centuries.

If you would like to read more information about the burials uncovered during the A1 upgrade then our first monograph, 'Death, Burial and Identity: 3000 Years of Death in the Vale of Mowbray', is now available to download for free via the ADS at: https://doi.org/10.5284/1050910.