7.1 Flat roofs, terraces and balconies

7.1.8 Profiled self-supporting metal roof decks

be constructed to ensure they achieve the required strength and durability, and be checked for conformity with the design upon delivery
comply with the manufacturer’s load and span tables and the relevant applied safety factor
conform to BS EN 1090-4 (steel) and BS EN 1090- 5 (aluminium) and resist loads in accordance with BS EN 1991-1-1,3 & 4 and be fixed in accordance with the manufacturer’s instructions
be side lap stitched to ensure it performs as a continuous plane layer (unless the manufacturer recommends otherwise)
be adequately protected from construction loads
be suitably stored to prevent damage.

be galvanised steel to BS EN 10346 (typical gauge range 0.7-1.2mm) or aluminium to BS EN 485-2 (minimum gauge 0.9mm) and used in accordance with BS EN 1993-1-3 and BS EN 1999-1-4 respectively
have a crown which is a minimum of 45% of the profile width (for bonded systems) (not including the crown stiffener grooves)
have a crown which is minimum of 40% of the profile width (for mechanically fixed systems)
be of suitable quality and finish before the waterproofing layer and insulation system is installed
be fixed using suitable fixings which avoid bimetallic corrosion in accordance with the manufacturer’s recommendations.

be a ‘warm’ or ‘inverted warm’ roof design
have drainage falls formed by installing the profiled metal sheeting at a slope or by use of tapered insulation
use insulation board with a compressive strength capable of spanning across the troughs of the profiled sheeting without crushing or be laid on a support board fixed across the profiles
use a reinforced air and vapour control layer, or AVCL recommended by waterproofing manufacturer, in warm roof build-ups where unsupported across the troughs
incorporate a support board fixed profiles in inverted warm designs to fully support the waterproofing layer.

Last updated: 2nd January 2024