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875 MEDIUM DENSITY FIBREBOARDgenerally
• Substrate: site specific.
- Additional supports: site specific.
• Medium density fibreboard: To BS EN 622-5, Type MDF.
- Manufacturer/ Supplier: Contractor's choice.
Product reference: site specific.
- Formaldehyde class to BS EN 622-1: Class site specific.
- Fire rating: site specific.
- Thickness: site specific.
- Edges: site specific.
- Recycled content: Submit proposals.
- Other requirements: site specific.
• Setting out: Long edges running across supports.
- Gap between adjacent boards: site specific.
• Fixing to supports:
- Fasteners: 35 x 3.5 mm countersunk woodscrews.
- Fixing centres (maximum):
Around board edges: 150 mm.
Along intermediate supports: 300 mm.
- Fixing distance from edges (minimum): 12 mm.
• Joint treatment: Bonded with PVA adhesive to BS EN 204, class D3.
• Accessories: site specific.

WORKMANSHIP

910 INSTALLATION GENERALLY
• Timing: Building to be weathertight before fixing boards internally.
• Moisture content of timber supports (maximum): 18%.
• Joints between boards: Accurately aligned, of constant width and parallel to
perimeter edges.
• Methods of fixing, and fasteners: As section Z20 where not specified otherwise.

930 ADDITIONAL SUPPORTS
• Additional studs, noggings/ dwangs (Scot) and battens:
- Provision: In accordance with board manufacturer's recommendations and as
follows:
Tongue and groove jointed rigid board areas: To all unsupported perimeter
edges.
Butt jointed rigid board areas: To all unsupported edges.
- Size: Not less than 50 mm wide and of adequate thickness.
- Quality of timber: As for adjacent timber supports.
- Treatment (where required): As for adjacent timber supports.

940 BOARD MOISTURE CONTENT AND CONDITIONING
• Moisture content of boards at time of fixing: Appropriate to end use.
• Conditioning regime: Submit proposals.

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