Cavity Trays discusses water evacuation in walls
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Cavity Trays explains why failure to provide adequate water evacuation from a cavity wall can cause major visual, internal and structural considerations.
Visually, external discolouration, salt emission and eventual permanent staining will blemish the appearance of the structure.
Internally, any sufficient water trapped or reservoirs within the cavity, will permeate inwardly.
If water is prevented from evacuating the structure, it will eventually find alternative routes.
Structurally, the masonry and mortar joints will suffer premature deterioration, and spalling will occur when trapped water freezes and expands, eventually resulting in masonry cracking, loosening and delaminating.
Cavity Trays also highlights that the need to drain cavity walls is not limited to window and door heads.
Changes of level, roofing intersections and ringbeams are further examples of construction that is reliant on water being adequately evacuated.
Caviweeps ensure water is not trapped within the structure but can exit speedily.
Cavity Trays manufactures five versions of caviweep in different colours including caviweeps with insect screening, discreet external appearance, and integral wind baffles, to suit all styles of mortar and masonry.
There are versions to suit masonry with drafted margins or restricted bed and perp joints as encountered with ashlar walling.
Once an external masonry leaf has become saturated and cannot absorb further rain, it acts as a conveyance sponge allowing up to 2.25 litres of water per hour can pass through every m2 of it during ongoing rain.
Some styles of masonry are more resilient to ingress, so wall design must always anticipate the most extreme exposure possibilities, so evacuation provision is always adequate.
Cavity Trays will be pleased to assist the optimisation of water evacuation provision upon request.
Where caviweeps are used with cavitrays manufactured by Cavity Trays, the combination benefits a performance warranty for the advantage of Architect Builder and Client.
Cavity Trays is the only cavity tray manufacturer awarded European Technical Approval.
Cavity Trays movement challenges the lastest British Standard PD 6697: 2010 detail that results in the entire parapet masonry above the DPC being separated from the masonry below the DPC and is not the ideal structural arrangement for a highly exposed wall at the top of a building. They outline why the use of preformed self-supporting Type P parapet cavitray is the preferred option.
Cavity Trays, already the only UK manufacturer of preformed cavitrays to hold European Technical Approval, has now secured additional approvals from LABC Registered Details (Local Authority Building Control) for preformed curved and straight cavitrays plus its extensive range of Cavicloaks.
Cavity Trays recommend the excellent thermal bridging junction details published by Constructive Details Ltd plus advise how some thermal junctions might be further enhanced.
Cavity Trays’ Type U undersill tray helps masons and designers achieve positive integration with the reveal closing.
Type LTT Level Threshold Trays are popular with house builders seeking a standardised level threshold specification solution.