NET PMC LTD undertake on site hose test witnessing in accordance with CWCT section 9 recommendations

- Neil Tolley, NET PMC Ltd.

Wrexham curve glazing

On Site CWCT Weather Test Witnessing

CWCT NET PMC LTD undertake on site hose test witnessing in accordance with CWCT section 9 recommendations. Set out below is the intent and procedures used. The field check is intended to determine the facades resistance to water penetration of only those joints in the wall, which are designed to remain permanently closed and watertight. If openable joints such as those around doors and openable parts of windows occur within the wall area involved, appropriate modifications both of procedure and performance requirements should be made in respect of such joints. This can be in the form of tape sealing the joints when brush seals with direct unbaffled paths from inside to outside exist. Alternatively with centre sealed windows designed to CWCT standards then a reduced to half pressure can be considered.

Working from the exterior, the wall test section shall be selectively wetted progressing from the lowest horizontal joint, then the intersecting vertical joints, then the next horizontal joint above, etc. The water shall be applied using a brass nozzle that will produce a solid cone of water droplets with a nominal spread of 30°. The nozzle shall be provided with a control valve and a pressure gauge between the valve and the nozzle. The water flow to the nozzle shall be adjusted to produce 22 ± 2 litre/min when the water pressure at the nozzle inlet is 2.2 ± 0.2 kPa. With the water directed at the joint and perpendicular to the face of the wall, the nozzle shall be moved slowly back and forth above the joint, at a distance of 0.3m from it, for a period of five minutes for each 1.5m of joint whilst an observer on the indoor side of the wall, using a torch if necessary, checks for any leakage and notes where it occurs.

CWCTIf no leakage occurs during the five-minute test, the next 1.5m of joint shall be wetted for five minutes, and testing continued until the entire test area is covered.