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515 PLYWOOD ROOF DECKING
• Substrate: site specific
- Additional supports: site specific.
• Decking: Plywood manufactured to the relevant standards and quality control
procedures specified in BS 5268-2, and so marked.
- Type: Contractor's choice.
- Grade: n/a.
- Nominal thickness/ number of plies: site specific.
- Edges: Tongued and grooved all edges.
- Other requirements: site specific.
• Setting out: Long edges running across supports. End joints central over joists and
staggered.
• Fixing:
- Fasteners: 50 mm x 8 gauge wood screws into pilot holes.
- Fixing centres:
Along each support: 25 mm from each long edge and at maximum 200 mm
centres between.
Around perimeter of roof area: Maximum 300 mm centres.
• Expansion provision:
- Clear expansion gap around perimeter of roof area and upstands: 10 mm.
- Intermediate expansion/ movement joints: As recommended by decking
manufacturer.

615 PLYWOOD SARKING
• Substrate: site specific.
- Additional supports: site specific.
• Sarking: Plywood manufactured to the relevant standards and quality control
procedures specified in BS 5268-2, and so marked.
- Type: Contractor's choice.
- Grade: n/a.
- Nominal thickness/ number of plies: site specific.
- Edges: Tongued and grooved all edges.
- Other requirements: site specific.
• Setting out: Long edges running across rafters. End joints central over rafters and
staggered.
• Fixing to each rafter:
- Fasteners: 50 mm x 8 gauge wood screws into pilot holes.
- Fixing centres (maximum):
Around roof perimeter and along short edges of each board: 150 mm.
Along intermediate supports: 300 mm.
- Fixing distance from edges: 25 mm from long edges and minimum 10 mm from
short edges.

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