Page 270 - McD_6118-AEW-XX-XX-NBS-A-001_Neat

640 LAYING WARM DECK ROOF INSULATION
• Setting out:
- Long edges: Fully supported and run at right angles to direction of span.
Joints: Butted together.
- Ends: Adequately supported.
Joints: Staggered.
• Bedding: site specific.
• Mechanical fixing: Six screws and washers per board to agreed pattern.
• Completion: Boards must be in good condition, well fitting and stable.

650 LAYING OVERLAY TO WARM DECK ROOF INSULATION
• Setting out:
- Joints: Butted together.
- End joints: Staggered to break joint with insulation.
• Bedding: Not required.
• Mechanical fixing: Six screws and washers per board to agreed pattern.

660 FIXING PERIMETER TRIMS
• Setting out: 3 mm clear from wall or fascia.
• Fasteners: 50 mm stainless steel countersunk wood screws to BS 1210.
- Fixing: 30 mm from ends and at 300 mm (maximum) centres.
• Jointing sleeves: Fixed one side only.
- GRP: Butt ends.
- Aluminium: 3 mm gaps between ends.
• Corners pieces: Purpose made.

670 INSTALLING ROOF VENTILATORS
• Setting out: Position evenly over roof area.
- Centres (maximum): site specific.
- Distance in from roof edge: site specific.
• Holes for ventilators: Cut neatly to suit size of vents through site specific.
• Priming/ Bonding:
- Substrate below vents: Do not prime or apply bonding compound.
- Vent skirts: Primed before application of roof coating if recommended by
manufacturer.

ROOF COATING SYSTEM

720 APPLYING PRIMERS/ CONDITIONERS
• Coverage per coat (minimum): manufacturers recomendation.
• Surface coverage: Brushed well in to ensure local or full area coverage according
to type.
• Coats: Allow to dry before overcoating.

740 MOVEMENT JOINTS IN SUBSTRATE
• Debonding tape: Apply over movement joints.
• Reinforcement strip: Apply over debonding tape.
• Bedding: Preliminary coating application.
• Joints: Lap in length.
• Bond: Continuous over whole surface, with no air pockets.
• Condition at completion: Smooth.

RotF generic (intermediate) NBS 2014 6118-AEW-XX-XX-NBS-A-01