The rules | Features

Comparison of CEN and CWCT requirements
Test	CEN European standard for curtain walling	CWCT UK standard for curtain walling
Watertightness	Water flow rate 2 l/min/m2	Water flow rate 3.4 l/min/m2
Wind resistance serviceability	Limit on deflection of framing members between points of attachment to structure 15 mm	Limit on deflection of framing members between points of attachment to structure 20 mm
	Residual deflection on unloading less than 5% of maximum	Residual deflection on unloading less than 1 mm
	Displacement at fixings to structure not greater than 1 mm
	Load applied once in 25% increments each maintained for 15 seconds	Load applied five times without increments and maintained for three seconds on each application
Repeat airtightness	Air leakage at peak pressure not to exceed result of initial test by more than 0.3 m3/h/m2	Air leakage to comply with requirements for first test
Repeat watertightness	Not required	Required
Dynamic watertightness	Optional in all cases	Optional for test pressures less than 600 pa. Required for higher test pressures
	Roving fan method	Aeroplane engine method
Wind resistance safety	No limit on deflection given	Permanent deformation of framing members shall not exceed 1/500 of the span measured between points of attachment to the building