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Restraint Straps (Domestic Roofs)
Lateral restraint of the walls can be provided by the roof, the restraint must be provided perpendicular to the roof trusses.
The information we provide has been compiled using the minimum requirement from Building Regulations 2010 approved document A, Scottish Building regulation domestic, NHBC standards and British Standard BS 5628–1;2005 Annex D.
ROOF
3RD STOREY
These have been issued as guidance only, the overall responsibility lies with the Building Designer.
2ND FLOOR
2ND STOREY
1ST FLOOR
1ST STOREY
GROUND FLOOR
3 STOREY HOUSE
Vertical Restraint Bent Strap To Wall Plate
Twisted Strap To Truss
RST strap to be nailed to truss with 3.4 x 35mm square twist nails. Nail quantity dependant on uplift value. Fixings into masonry to be specified by building designer. Please refer to page 135 for further information on RST straps
Fix VRS or LDGS to the wall plate with 2No 3.4 x 35mm square twist nails. Fixings into masonry to be specified by building designer. Please refer to page 136 for further information on VRS straps
Horizontal Restraint (Masonry Gables)
Floor Level
Detail
Region
Up to and including 2 storeys
3 storeys
4 storeys
PFS required at 2m max centres
PFS required at 1.25m max centres
England & Wales
Perpendicular
PFS required at 2m max centres
PFS required at 1.25m max centres
Scotland
— Straps to be installed at not more than 2m centres (or 1.25m where appropriate) along gable end. — Strap to be of sufficient length to be fixed to a minimum of 3no. Trusses. — Longitudinal bracing to be fixed to each truss with 2no. 3.35 x 65mm round wire nails (in all details 3.1 x 90mm long mechanically driven nails may be substituted for 3.35 x 65mm long wire nails). — Where the position of the strap does not coincide with an existing longitudinal truss brace, then the strap may be fixed to an additional 25 x 100mm longitudinal binder (as shown in following details ). The binder to be fixed over a minimum of four trusses and fixed to each truss with 2no. 3.35 x 65mm round wire nails. — Fix straps to longitudinal bracing with 8no. 3.4 x 35mm square twist nails, evenly spaced along the length of the strap (for NHBC warrantied buildings, in accordance with NHBC Standards 2017 section 7.2.8, 8no. 25 x 4mm steel screws shall be used instead of square twist nails). — Parallel restraint straps are not required to roof trusses unless specified by building designer.
The latest most up to date version will always be online and not in print or in downloaded pdf.
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Technical support 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk
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