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715 PLYWOOD UNDERLAY
• Substrate: site specific.
- Condition: Sound and acceptably level.
- Preparation: Gross irregularities removed or filled. Protruding fasteners removed
or punched in.
• Underlay: Plywood to an approved national standard.
- Bonding quality to BS EN 314-2: site specific.
- Appearance class to BS EN 635: Class site specific.
- Finish: Sanded.
- Thickness: site specific.
- Sheet size: 2440 x 1220 mm.
• Setting out: End joints staggered and a 0.5-1 mm gap between adjacent sheets.
Joints in underlay offset from joints in substrate.
• Fixing:
- Fasteners: mechanical fixings to suit substrate.
Fastener heads: Set flush with sheet surface.
- Fixing centres: 150 mm grid over each sheet commencing at centre. Maximum
100 mm centres around perimeter, set in 12 mm from edges.

815 PLYWOODgenerally
• Substrate: site specific.
- Additional supports: site specific.
• Plywood: Manufactured to an approved national standard.
- Manufacturer/ Supplier: Contractor's choice.
Product reference: site specific.
- Face veneer species: Contractor's choice; biological durability appropriate for
plywood subject to the risk of attack outlined in BS EN 335-3, hazard class 3.
- Face grain direction: parallel to long edges of boards.
- Bonding quality to BS EN 314-2: site specific.
- Appearance class to BS EN 635: Class site specific.
- Finish: site specific.
- Thickness: site specific.
- Edges: site specific.
- Treatment: site specific.
- Other requirements: site specific.
• Setting out: Long edges running across supports.
- Gap between adjacent boards: site specific.
• Fixing to supports:
- Fasteners: 50 mm x 8 gauge wood screws into pilot holes.
- Fixing centres (maximum):
Around board edges: 150 mm.
Along intermediate supports: 300 mm.
- Fixing distance from edges (minimum): 10 mm.
• Joint treatment: Bonded with PVA adhesive to BS EN 204, class D3.
• Accessories: site specific.

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