Single Skin Metal Cladding

1.0 Design

Complete the design of the Coverworld Cladding System in accordance with BS5427 Part 1 and the requirements of the Coverworld Specification.

2.0 Loading

2.1 Wind Loading

Wind Loading is to be calculated appropriate to location, exposure, roof height, building shape and size in accordance with BS 6399 : Part 2

2.2 Imposed & Snow Loading

Imposed & Snow Loading is to be calculated in accordance with BS 6399 : Part 3

2.3 Dead Loading

Where appropriate dead loading is to be included in the design.

3.0 Deflections

Deflection is to be limited to:
3.1 Wind load Span / 150
3.2 Dead and Imposed load Span / 200
3.3 Dead Load Span / 500

4.0 U Value Calculation

The U value requirement is to be determined by Building Regulations, approved Document ‘L’. Coverworld twin skin, (built-up), systems will comply using Covergrid spacer system and an appropriate type and thickness of insulation. Other factors such as detailing at junctions and air tightness have a major influence on the overall result.

5.0 Fire Resistance

Coverworld steel sheeting is non combustible and will not contribute to a fire. Coverworld coated steel sheeting achieves the following;
BS 476 Part 3 (External Roofing) Class SAA
BS 476 Part 5 (Ignitability) P – not easily ignitable
BS 476 Part 6 (Fire Propagation)Passed
BS 476 Part 7 (Surface Spread of Flame) Class 1

Coverworld coated steel sheeting achieves a Class O rating in the Building Regulations.

6.0 Materials

Coverworld steel sheeting is profiled from alloy coated flat steel sheet manufactured to EN 10147:1992.

7.0 Finishes

Coverworld steel sheeting has a reverse coat of grey back coat. The exposed face is supplied in one of the following finishes.
Plastisol: 200-micron external grade PVC coating.
PVDF: 35-micron thick coating.
Polyester: 25-micron thick coating.
Lining Enamel: 15-micron thick coating.

8.0 Colour

A full colour range for each coating type is available as detailed in data published by Coverworld. Lighter colours are recommended for roofing.

9.0 Fixing of Sheeting

For Coverworld double skin construction do not line out building completely before installation of outer sheets. Cut sheets and flashings to give clean true lines, with no distortion. Remove burrs and any lubricant. Lay Coverworld sheets with exposed joints of side laps away from prevailing wind unless shown otherwise on drawings.

Cut openings in Coverworld sheets for outlets, vent pipes, flues, etc. to the minimum size necessary, Reinforce edges of openings. Ensure that raking cut edges at hips and valleys are fully supported. Ensure that ends of sheets, and end laps are fully supported with fixings at top of lap.

Drill all holes and install fasteners perpendicular to the surface of Coverworld cladding. Position fasteners at regular intervals in straight lines, centred on support bearings. Locate fasteners centrally within holes that are oversized. Remove dust and any other foreign matter before finally fixing sheets into position. Install fasteners to correct tightness using any special tools recommended by the fastener manufacturer. When used, screw guns must be fitted with depth sensitive devices and used at the correct speed.

Protect Coverworld sheets adequately during fixing and up to Practical Completion against mechanical damage and disfigurement. Rectify any defects as quickly as practicable to minimise damage and nuisance. Check fastenings on completion and adjust as necessary to ensure that they are watertight and sheeting is secure but not buckled or distorted. Paint all cut edges to match face finish.

10.0 Fixing of Rooflights

Size fixing holes in accordance with sheet manufacturer’s recommendations. Crown fixing: Where primary fastenings occur in sheets with profile heights in excess of 20 mm, support crowns of profiles with profile fillers. Seal end laps between plastics profiled sheets with two strips of sealing tape, one along each edge of lap, to prevent future build up of dirt between sheets.

Fix liner and outer sheets progressively from one end to avoid distortion. Install spacers and outer sheets immediately after liner sheet installation. Before fixing ensure that surfaces which will be inaccessible are clean. Seal laps of both inner and outer sheets.

11.0 Structural Movement Joints

Leave space between Coverworld sheets to coincide with structural movement joints. Fix weather tight movement joint cover to sheets on one side only.

12.0 Fixing Flashings and Trims

Coverworld Flashings and trims to be lapped at joints as follows, unless specified otherwise. Vertical and sloping flashings/trims: End laps to be the same as for adjacent sheeting. Horizontal flashings/trims: End laps to be 150 mm, sealed and where possible arranged with laps away from the prevailing wind. Where possible fix flashings/trims to structure in conjunction with adjacent Coverworld sheeting. Otherwise fix securely to sheeting.

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