Siniat deflection heads can cater for both upwards and downwards deflection up to a maximum of 40mm total movement.

With any deflection head, there must be a minimum of 5mm overlap between the main system boards and head packers at any extent of movement.

The number of packers must be suitable for the total amount of deflection plus minimum 5mm.

The boards must then be cut short of the soffit by the downward deflection amount as well as have the overlap onto the packers of the upwards deflection plus 5mm.

This ensures the minimum 5mm overlap is maintained at the upward deflection extent.