BS 5534 provides recommendations for the use of mortar to bed roof fittings and accessories and requires all components to be additionally mechanically fixed to the roof structure using proprietary fixings. This recommendation acknowledges potential shortcomings with the performance and durability of mortar to resist the wind loads on roof fittings and accessories.
Dry Fix systems that meet the requirements of BS 8612 (as manufactured by Marley) are acknowledged as an alternative to mortar and perform both a gap closing and mechanical fix for roof fittings and components. Dry ridge and hip systems also incorporate ventilation which avoids the need for separate ventilation ridge tiles or roof slope ventilators.