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 including relevant applied safety factors
conform to BS EN 1090-4 (steel) and BS EN 10905 (aluminium)
resist loads in accordance with BS EN 1991-1-4
be fixed in accordance with the manufacturer’s instructions with side laps stitched to ensure performance as a continuous structural plane (unless a manufacturer and design specialist 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
for bonded systems — have a crown which at least 45% of the profile width, not including the crown stiffener grooves
for mechanically fixed systems — have a crown which at least 40% of the profile width, not including the crown stiffener grooves
be of suitable quality and finish before the waterproofing layer and insulation system is installed
be fixed using suitably specified 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 fitted at a slope or by use of tapered insulation
use an insulation board product with a compressive strength capable of spanning across the troughs of the profiled sheeting without crushing, or be laid over support boards fixed across the profiles
in warm roof build-ups where unsupported across the troughs, use a reinforced AVCL, or AVCL recommended by the waterproofing manufacturer
for inverted warm roof designs, these should incorporate support boarding fixed across profiles to fully support the waterproofing layer.

Last updated: 2nd January 2025