The profile of an arch does not lend itself to simple positioning of
a damp proof course. At best, it can be located horizontally at
upper extrados level. This leaves the depth of the arch and
masonry below the dpc vulnerable to dampness. Proprietary
galvanised or stainless steel cavity trays resolve this problem by
providing:* Continuity of dpc around the extrados.* Arch support/centring during construction.* Arch and wall support after construction.Standard profiles are made to the traditional outlines shown on
the previous two pages, in spans up to 2 m. Other options may
also be available from some manufacturers. Irregular shapes and
spans can be made to order.Note: Arches in semi-circular, segmental or parabolic form up to
2m span can be proportioned empirically. For integrity of structure
it is important to ensure sufficient provision of masonry over and
around any arch, see BS 5628: Code of practice for use of
masonry.Arch Cavity Tray