Twin Skin Metal Profiled Roof Cladding

ROOF – minimum pitch 4°

1.0 External Sheet
1.1 External Sheet Specification
External Sheet to be Coverworld 32R, 34R, 38R or 24R profile, Aluzinc coated steel substrate to 0.70mm nominal thickness, including alloy coating.

1.2 External Sheet Finish

External finish to be Plastisol in standard colour. Reverse coat grey backing coat.

1.3 External Sheet Fasteners

Fasteners to be approved self drilling screws with stainless steel bonded washers 16mm diameter to specification recommended by fixings supplier, with caps to colour match outer sheet. Fasteners to be fixed through profile trough at every pitch at eaves and end laps and at every second profile pitch at intermediate supports.

1.4 External Sheet End Laps

End laps to be a minimum length of 150mm and sealed at each end. Sealant to be 9mm wide by 3mm thick cross linked butyl rubber placed not more than approximately 5mm from the edge of the overlap sheet.

1.5 External Sheet Side Laps

Side laps are to be laid away from the direction of the prevailing wind, where possible. Where this is not possible, or in exposed locations, the side laps are to be sealed with 9mm wide by 3mm thick cross-linked butyl rubber.

1.6 External Sheet Profile Fillers

Profile Fillers to be polyethylene foam, tightly fitted under ridge and hip flashings and at eaves.

2.0 Spacers
2.1 Spacer Specification

Spacer system to be Coverworld Covergrid System consisting of structural grade galvanised steel bars and bracket supports with thermal break seal pads. Bracket size 60mm – 280mm to accommodate required insulation thickness and ‘U’ value.

2.2 Spacer Fixings

Spacer system to be fixed to purlins with self-drilling screws, (normally two per bracket), minimum length 25mm.

3.0 Thermal Insulation
3.1 Insulation Specification

Thermal Insulation to be mineral fibre roll. All edges to be close butted to achieve continuity. Ensure insulation is not compressed between outer and liner sheets.

3.2 Insulation Thickness

To be as required to achieve the specified ‘U’ value.

4.0 Lining
4.1 Lining Specification

Lining to be Coverworld CL20 in hot-dip zinc coated steel, 0.4mm nominal thickness, including alloy coating.

4.2 Lining Finish

Liner coating to be Lining Enamel with bright white internal finish and grey backing coat.

4.3 Lining Fasteners

Liner profile to be fixed with self drill screws at every second trough to each support.

4.4 Lining End and Side Laps

End laps to be not less than 40mm long. Side and end laps to be sealed using self-adhesive metalized foil tape.

4.5 Lining Openings

All openings cut through the liner panel must be vapour sealed

4.6 Lining Sheet Profile Fillers

Profile fillers to be polyethylene foam, tightly fitted so as to prevent ingress of internal building air into the roof void.

5.0 Flashings and Trims
5.1 Flashings Specification

External and internal flashings and trims to be manufactured from the same material as the Coverworld sheet used adjacently. Flat dimensions exceeding 200mm are to have a bend or stiffener in order to avoid ‘oil canning’.

5.2 Flashings Fasteners

Flashings and trims to be fixed at centres not exceeding 300mm using screws or sealed aluminium rivets at 150mm maximum centres.

5.3 Flashings Laps

Vertical and sloping flashings are to have the same end lap detail as the adjacent Coverworld sheeting. Horizontal flashings should have butt end joints, with the joint covered by a 150mm butt strap sealed to the flashing at each end.