Double Arrestment Benefit of Multi-Opening Cavitray   

Absorption areas of masonry around and above openings must be taken into account where the proximity of those openings is less than 900mm distance. This rule of thumb measurement ensures adequate provision is made to control concentrations of arrested water that could be problematic if allowed to gravitate downwardly in the usual way. 

Water penetrating masonry and then circumventing a circular opening will discharge at the lowest point, (6 o’clock). In the example shown the discharge point is immediately adjacent to and between two arched openings. Both arch openings also discharge water into the same area. Therefore the narrow pier is likely to become exceedingly wet during extended periods of heavy rain. Additionally it must be remembered that all the masonry rising above the openings will also become saturated, and that water will also gravitate and place descend to opening level. 

The masonry area rising immediately above the openings in this example extend to over 20 sq metres – the majority of which will end up heading towards one small dividing pier. 

Cavity Trays Ltd offers the complete solution in the form of a multiple aperture cavitray with an integral arresting barrier. 

The upper part of the cavitray incorporates an arresting barrier that receives the majority of water gravitating within the cavity and masonry. Each end of this arresting section extends outwardly. Thus before the openings level is reached, the water is arrested and discharged via caviweeps located 900mm clear of the openings. 

With the majority of descending water exiting via offset evacuation routes, the circular opening and both arch openings are subjected to minimal volumes. The triple opening cavitray ensures internally each maintains a damp-free status and the pier does not overload and visually discolour externally through water staining and crystalline deposits. 

Cavity Trays of Yeovil is the only cavity trays manufacturer awarded European Technical Approval and operates its bespoke service providing products with product performance liability protection for the benefit of Architect Builder and Client. 

Cavity Trays Limited Administration Centre Yeovil Somerset BA22 8HU               

T: 01935 474769 

F: 01935 428223     

enquiries@cavitytrays.co.uk     

www.cavitytrays.com