When the recently enlarged bespoke production unit at Cavity Trays of Yeovil was asked to design bespoke damp-protection for openings on a large apartment scheme, it came up with a cost-effective, thermally efficient and speedy-to-install proposal.

The construction of blue lias with projecting hamstone features required horizontal DPC protection across the window head that also extended downwardly to provide insulated reveal-protection. The hamstone was thus separated from but linked with the outer and inner masonry skins. At the bottom of the opening the insulated reveal protection interfaced with a sill Cavitray, so that every opening was effectively framed with an uninterrupted arrangement. Bonded to the rear face of each protective frame was phenolic insulation to provide thermal zoning around the entire opening, to more than satisfy the calculated regulation levels.

One of the benefits of the bespoke design was that protection could be standardised in profile, yet applied on openings of different and variable dimensions. This meant the masons could adhere to an uninterrupted build sequence. Each opening could be packaged and numbered, to simplify stock control. The waste factor encountered with site-fabricated approaches could be eliminated and installation speed maximised.

Water arrested by bespoke Cavitrays is discharged via discreet Caviweeps. These cannot be detected in the stone face – unless one looks very closely.

Caviweep evacuation rate is influenced by the absorption area (extent of continuous masonry) rising above each opening. In such stonework the anticipated flow usually remains relatively constant during the initial years but commonly rises after year five as fissures and fine settlement cracks (often at junctions between dissimilar materials) contribute to water ingress opportunities.

Using preformed Cavitrays, Caviclosers and Caviweeps in standard or bespoke form provides designer and contractor with an assured and warranted solution for every opening within a cavity wall.