Cavity Trays discusses water evacuation in walls
Cavity Trayscontact supplier
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.
Type BA Cavity Barrier Arch cavitrays from Cavity Trays have been designed for use in shaped rather than horizontal cavity walls to provide opening protection. Type BA cavitrays offer total protection to the angled head, extending upwardly and outwardly to prevent the build up of concentrated water wash.
New Pyramid Weep for cavity masonry download
The new Pyramid Weep for cavity masonry from Cavity Trays replaces traditional reed straw systems. Triangular in profile, the new weep provides an aesthetically neutral means of removing water that may permeate a structure. The possible flow width of the weep is maximised due to its flat base which also allows it to bed as flat and low as possible to service water evacuation from lintels, dpc’s and trays. The Pyramid Weep is manufactured using PVCu and, as a result, will not rot.
Cavity Trays is reporting that cavity walls that support an opening using separate lintels will improve the overall thermal performance of the structural opening as the lintels do not connect and therefore do not conduct heat loss. Using this method alongside a self-supporting Cavitray and an infilling profile Cavistock enhances performances levels even further. This arrangement can promote a lintel value of up to 0.05W/mk.
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.