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SYSTEM PERFORMANCE

210 RETENTION STRUCTURE DESIGN
• Requirement: Design, erect and maintain retention structure to hold façade in
position without overstress or undue deflection of façade or retention structure.
- Additional requirements: Crash barrier to protect façade/ retention structure
from vehicle impact, other; site specific.
• Design parameters:
- Spacing of supports (maximum): To prevent overstressing of masonry and restrict
deflection under wind loading to distance between supports.
- Loads: As specified.
- Load combinations for strength: As CIRIA report C579, section 8.12.
- Load combinations for lateral deflection: Dead loads, plus adverse imposed
loads and, where applicable, earth loads plus adverse wind loads.
- Lateral movement of façade (maximum): Restrict total movement due to load
on retention structure and façade, plus thermal effects on retention structure to A
t top of façade: Total height of façade to site specific point.
- Factor of safety against overturning/ sliding: 1.5 for resistance against overturning
and 2.0 for resistance against sliding.
• Design standard: BS 5975.
- Provisos: Imperfections for scaffold tubes assumed as BS EN 12811-1, clause
10.2.2.2.
- Substitution of alternative standards: Steelwork to BS 5950-1.
• Design proposals: Submit detailed drawings and calculations. Resolve
amendments before starting work.

230 RESPONSIBILITY
• Requirement: Accept responsibility for adequacy, stability, integrity and rigidity of
façade and retention structure for duration of works.

270 FOUNDATIONS AND KENTLEDGE
• Requirements:
- At façade end of retention structure: Provide new foundations and kentledge or
demonstrate that existing structure can be used without distress to façade.
- At outer end of retention structure: Contractor's choice.
- Other requirements: Keying into façade for kentledge to be in existing openings
or below ground level.
• Ground investigation report: Confirm as adequate or submit proposals for further
investigation as considered necessary.

280 CONNECTIONS BETWEEN FAÇADE AND SUPPORT STRUCTURE
• Requirements:
- Horizontal loads: To be transferred from façade to restraining structure without
slip in compression or tension.
- Differential vertical movement: Accommodate between façade and retention
structure, without connection binding.

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