Installation: Rules, Sequence & Key Numbers

Five rules govern a sound ASA resin roof: 660mm purlin spacing, bottom-up laying, one-wave laps, pre-drilled fixings and correctly finished ridges.

Five Installation Rules

• Rule 1 - Purlins. Use square tube 60 x 40 x 3mm, C-channel steel 100 x 50 x 20 x 3mm, or anti-corrosion wood 60 x 40mm, set at a 660mm purlin spacing.
• Rule 2 - Direction. Lay main tiles from bottom to top, against the prevailing local wind direction, and work both slopes at the same time so the ridge stays aligned.
• Rule 3 - Laps. Overlap each side joint by one full wave. Lengths are ordered in multiples of the 219mm step pitch so end laps land correctly.
• Rule 4 - Fixings. Always pre-drill before fixing. The hole must be 2mm larger than the hook or screw shank to allow thermal movement. Recommended fastener: 6.3mm diameter self-tapping screws.
• Rule 5 - Ridges. Cut the first section of the main ridge tile before fitting, and saw ridge tile joints flush so adjoining pieces sit tight and neat.

Working Sequence

First, set out and fix the purlins at 660mm centres and check the roof plane. Second, lay main tiles from the eave upward against the wind, one wave per side lap, advancing on both slopes together. Third, pre-drill every fixing hole 2mm oversize and fix with 6.3mm self-tapping screws - never drive screws through undrilled sheet, which can crack the tile and blocks thermal expansion. Fourth, fit the main ridge after cutting its first section, then the tilted ridges, ridge ends and two-way or three-way junctions from the accessory system, sawing each ridge joint flush. Finally, walk the roof once to check laps, fixings and ridge alignment.

Key Numbers at a Glance

Full step-by-step guidance is in the guide How to install ASA resin roof tiles. Technical support, including layout drawings and accessory lists, is included for agents and project orders - see trade and contact.