ITW Cullen Gable Restraint System 2024

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Gable Restraint System Technical Guide UP TO 5 STOREYS

Gable Restraint System

ITW Construction Products’ Cullen brand of timber engineering connectors has been synonymous with innovation and quality for over forty years. In collaboration with national housebuilders, the Trussed Rafter Association and industry partners, ITWs technical experts have created an innovative system featuring the Cullen Gable Restraint Bracket for a complete

on the masonry and timber gable ends into the braced roof diaphragm. This provides a verified connection between timber gable panels to masonry walls. The details give an option to have a continuous wall plate or a stepped wallplate with the gable wall plate being raised to suit the bottom chord depth of the truss. Either of the details meets the requirement of Building Regulations 2010 approved document A, Scottish Building regulations domestic, NHBC Standards for houses

of five storeys or less in England and Wales and four storeys or less in Scotland. Both details are accepted by NHBC. This NHBC accepted “whole system” solution incorporating the Cullen Gable Restraint Bracket and restraint straps including Paslode nail fixings with all centres, spacings and connections already calculated means that whenever our detail is followed the system is underwritten by ITW Construction Products.

solution to connect timber gables to masonry walls.

The details have been developed to safely transfer lateral wind load

Please note the GRB forms part of a system and must be used in conjunction with the system straps and fixings as shown below.

The Gable Restraint System is comprised of the following specified products:

GRB-100

VRS-900-100

Patent Pending

Establishes a verified connection between a timber gable and a masonry wall.

Provides a secure method of fixing wall plates to timber and masonry walls.

RST-3

PFS-1500-100-B

FT: The Timber Frame Wall Tie

A high-performance strap developed to resist uplift and provide lateral restraint for timber gables.

Delivers superior performance and exceptional flexibility, ideal for lateral restraint in floor and roof applications.

Restrains the external blockwork or brickwork back to the timber frame structure.

The latest version of the technical guide will always be the digital format on our website.

Technical support: 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk 2

Gable Restraint Bracket & Application

Gable panel Timber wallplate Mortar bed

Gable restraint bracket

Masonry wall

Gable Restraint Bracket Installation

Components: – Wallplate – Mortar – Gable Restraint Brackets – Wall

Gable restraint brackets placed on wall at 1200mm* maximum centres (no fixings required). *for buildings up to 3 storey England & Wales and 2 storey Scotland

10mm maximum mortar bed on wall prior to wallplate being fixed.

38-75mm wallplate bedded on mortar and fixed to gable restraint brackets with 3.5x40mm wood screws (2 no. per bracket).

Gable Restraint Bracket Installation Video

Scan or click to view installation videos

The latest version of the technical guide will always be the digital format on our website.

Technical support: 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk 3

Gable Restraint System

Class 1 Buildings / houses of single occupancy three storeys or less England & Wales and two storeys or less Scotland Timber Gable to Masonry fixing detail to cold roofs – continuous wallplate

Gable Panel

225mm maximum height between underside of wallplate and horizontal restraint strap

Insulation continued into gable panel

Breather membrane to face of gable panel

Roof insulation

Cullen FT Timber frame wall ties

Longitudinal truss bracing

Continuous wallplate 38mm min-75mm maximum depth

Level of truss wallplate

Solid blocking between truss and gable panel at horizontal restraint strap positions Gable panel to wallplate fixing - Paslode 3.1mm dia x min 75mm long smooth shank nails at maximum 175mm centres Vertical holding down strap plugged and screwed to blockwork

Mortar bed

Cullen RST-3 restraint straps at maximum 1200mm centre fixed to longitudinal truss bracing /

Cullen Gable Restraint Bracket (GRB) at maximum 1200mm centres

additional longitudinal bracing with 8 no. 4 x 25mm steel screws fixed to gable panel stud with 3 no. 3.4 x 35 mm square twist nails

Cavity insulation shown for indicative purposes only - thermal bridging and SAP calculations are plot specific Cavity trays and firestops to be detailed by building designer

at maximum 1.8m centres, Cullen VRS-900-100 strap

Gable Panel (without gable ladder)

Cullen PFS restraint straps fixed to solid timber noggins between trusses at maximum 2000mm centres with 3.4 x 35mm square twist nails, 8 no. to noggins and 4 no. to gable panel (2 no. top face & 2 no. cavity face)

Cullen RST-3 restraint straps at maximum 1200mm centres fixed to additional longitudinal bracing with 8 no. 4 x 25mm steel screws fixed to gable panel stud with 3 no. 3.4 x 35mm square twist nails

Gable Panel (with or without gable ladder)

Truss profile

Bottom rail of gable panel

Continuous wallplate 38mm min-75mm maximum depth

1200mm max

Mortar bed

1200mm max

Cullen Gable Restraint Bracket (GRB) at maximum 1200mm centres

Cullen VRS-900-100 fixed to top of bottom rail with 4 no. 3.4 x 35mm square twist nails

1800mm maximum

Vertical restraint strap plugged and screwed to blockwork at maximum 1.8m centres - Cullen VRS-900-100 installed to top of gable panel bottom rail

The latest version of the technical guide will always be the digital format on our website.

Technical support: 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk 4

Class 1 Buildings / houses of single occupancy three storeys or less England & Wales and two storeys or less Scotland

Timber Gable to Masonry fixing detail to cold roofs – raised gable wallplate Cavity trays and firestops to be detailed by building designer Gable Panel

Breather membrane to face of gable panel

Insulation continued into gable panel

Cullen FT Timber frame wall ties Wallplate 38mm min- 75mm maximum depth

Roof insulation

Longitudinal truss bracing (depth can vary to suit blockwork level)

Mortar bed

Level of truss wallplate

Levels to be adjusted to ensure top of bracing inline with top of blockwork Cullen Gable Restraint Bracket (GRB) at maximum 1200mm centres Cavity insulation shown for indicative purposes only - thermal bridging and SAP calculations to be plot specific

Solid blocking between truss and gable panel at horizontal restraint strap positions Gable Panel to wallplate fixing - Paslode 3.1mm dia x min 75mm long smooth shank nails at maximum 175mm centres Vertical holding down strap plugged and screwed to blockwork at maximum 1.8m centres Cullen VRS-900-100 strap

Cullen PFS-1500-100-B restraint straps at maximum 2000mm centre fixed to longitudinal truss bracing / additional longitudinal bracing with 8no. 4x25mm steel screws fixed to gable panel stud with 3no. 3.4x35mm square twist nails

Gable Panel (with or without gable ladder)

Gable Panel (without gable ladder)

Truss profile

Bottom rail of gable panel

Cullen VRS-900-100 fixed to top of bottom rail with 4 no. 3.4 x 35mm square twist nails Cullen PFS restraint straps bedded in mortar joint between top of masonry and wallplate and fixed to longitudinal truss bracing maximum 2000mm centres with 8 no. 4 x 25mm steel screws

Continuous wallplate 38mm min-75mm maximum depth

2000mm max

Mortar bed

1200mm max

Cullen Gable Restraint Bracket (GRB) at maximum 1200mm centres

1800mm maximum

Vertical restraint strap plugged and screwed to blockwork at maximum 1.8m centres - Cullen VRS-900-100 installed to top of gable panel bottom rail

The latest version of the technical guide will always be the digital format on our website.

Technical support: 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk 5

Gable Restraint System

Class 1 Buildings / houses of single occupancy three storeys or less England & Wales and two storeys or less Scotland Openings within gable walls

When GRB & VRS restraint straps clash with opening positions and cavity trays above openings please position to suit the following – these details can be applied to continuous & raised wallplate.

Repositioned / additional GRB to be kept back from opening to avoid clashing with cavity tray.

3600mm maximum

300mm min

150mm min

1200mm max

2400mm maximum opening width

300mm min

1800mm maximum

3600mm maximum

1800mm maximum

Repositioned / additional VRS holding down strap either side of opening.

Where large door / window openings GRB’s / VRS restraint straps to be repositioned / additional installed either side of the opening with maximum and minimum centres shown above.

The latest version of the technical guide will always be the digital format on our website.

Technical support: 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk 6

Timber Gable to Masonry Blockwork External - wall tie requirements

Maximum Net Surface Wind Pressure

Cullen FT-100 = 1.279kN/m 2 3.7 ties/m 2 (450mm vertical & 600mm horizontal centres)

mber Gable to Masonry Blockwork External - wall tie requirements mber Gable to Masonry Blockwork External - wall tie requirements mber Gable to Masonry Blockwork External - wall tie requirements Cullen FT-100 = 2.558kN/m 2 7.4 ties/m 2 (225mm vertical & 600mm horizontal centres)

Minimum of 1 tie must be positioned in this zone at 600mm horizontal centres. 2 sets of wall ties with at least 1 tie positioned within 225mm of top of gable panel. Ties positioned at maximum of 225mm vertical & 600mm horizontal centres. Wall ties for general area positioned at maximum of 450mm vertical & 600mm horizontal centres (vertical centres can be reduced to 225mm if required by Building Designer). 2 sets of wall ties positioned at maximum of 225mm vertical & 600mm horizontal centres from bottom of gable panel. Top row of masonry wall ties provided at 300mm centres maximum.

Minimum of 1 tie must be positioned in this zone at 600mm horizontal centres.

600 600

600

The latest version of the technical guide will always be the digital format on our website.

Technical support: 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk 7

Gable Restraint System

Timber Gable to Masonry Brickwork External - wall tie requirements

Maximum Net Surface Wind Pressure

Cullen FT-100 = 1.279kN/m 2 3.7 ties/m 2 (450mm vertical & 600mm horizontal centres)

mber Gable to Masonry Brickwork External - wall tie requirements Cullen FT-100 = 2.558kN/m 2 7.4 ties/m 2 (225mm vertical & 600mm horizontal centres) imber Gable to Masonry Blockwork External - wall tie requirements imber Gable to Masonry Blockwork External - wall tie requirements

Minimum of 1 tie must be positioned in this zone at 600mm horizontal centres. 2 sets of wall ties with at least 1 tie positioned within 225mm of top of gable panel. Ties positioned at maximum of 150mm vertical & 600mm horizontal centres. Wall ties for general area positioned at maximum of 450mm vertical & 600mm horizontal centres (vertical centres can be reduced to 225mm if required by Building Designer) 2 sets of wall ties positioned at maximum of 150mm vertical & 600mm horizontal centres from bottom of gable panel. Top row of masonry wall ties provided at 300mm centres maximum.

Minimum of 1 tie must be positioned in this zone at 600mm horizontal centres.

600

600 600 600

600

600 600

The latest version of the technical guide will always be the digital format on our website.

Technical support: 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk 8

Jointing of panels

Fixing must be positioned maximum of 150mm from edge of panel (top & bottom)

38 x 89mm panels - PSTS-6.5 x 65mm screws at maximum of 333mm centres

47 x 97mm panels PSTS-8 x 85mm screws at maximum of 500mm centres

To meet the requirements of EN1995-1-1:2004+A2:2014 “the required vertical connection strength between two panels should be evaluated but should have a design strength of at least 2,5 kN/m”.

To achieve this panels are to be fixed using the following Paslode structural timber screws or the Paslode nail fixing.

Panel thickness where screw head is located (mm)

Panel thickness where screw point is located (mm)

Fixing type

Fixing Centres (mm)

PSTS-6.5 x 65 PSTS-8 x 85 Paslode 3.1 x 65 Paslode 3.1 x 90

38 47 38 47

333 500 130 130

The latest version of the technical guide will always be the digital format on our website.

Technical support: 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk 9

Gable Restraint System

Class 2a Buildings / houses of single occupancy five storeys or less England & Wales and four storeys or less Scotland

Timber Gable to Masonry fixing detail to cold roofs – continuous wallplate

Gable Panel

225mm maximum height between underside of wallplate and horizontal restraint strap

Insulation continued into gable panel

Breather membrane to face of gable panel

Roof insulation Longitudinal truss bracing

Continuous wallplate 38mm min-75mm maximum depth Cullen FT Timber frame wall ties

Level of truss wallplate

Solid blocking between truss and gable panel at horizontal restraint strap positions Gable Panel to wallplate fixing - Paslode 3.1mm dia x min 75mm long smooth shank nails at maximum 100mm centres Vertical holding down strap plugged and screwed to blockwork at maximum 1.8m centres, Cullen VRS-900-100

Mortar bed

Cullen RST-3 restraint straps at maximum 750mm centres fixed to longitudinal truss bracing / additional longitudinal bracing with 8 no. 4 x 25mm steel screws fixed to gable panel stud with 3 no. 3.4 x 35mm square twist nails

Cullen Gable Restraint Bracket (GRB) at maximum 750mm centres Cavity insulation shown for indicative purposes only - thermal bridging and SAP calculations to be plot specific

Cavity trays and firestops to be detailed by building designer

Gable Panel (without gable ladder)

Cullen PFS restraint straps fixed to solid timber noggins between trusses at maximum 1250mm centres with 3.4 x 35mm square twist nails, 8 no. to noggins and 4 no. to gable panel (2 no. top face & 2 no. cavity face) Cullen RST-3 restraint straps at maximum 800mm centres fixed to additional longitudinal bracing with 8 no. 4 x 25mm steel screws fixed to gable panel stud with 3 no. 3.4 x 35mm square twist nails

Truss profile

Gable Panel (with or without gable ladder)

Continuous wallplate 38mm min-75mm maximum depth Bottom rail of gable panel

800mm max 800mm max

800mm max

800mm max800mm max

Mortar bed

750mm max 750mm max 750mm max 750mm max

Cullen Gable Restraint Bracket (GRB) at maximum 750mm centres

Cullen VRS-900-100 fixed to top of bottom rail with 4 no. 3.4 x 35mm square twist nails

1800mm maximum

Vertical restraint strap plugged and screwed to blockwork at maximum 1.8m centres - Cullen VRS-900-100 installed to top of gable panel bottom rail

The latest version of the technical guide will always be the digital format on our website.

Technical support: 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk 10

Class 2a Buildings / houses of single occupancy five storeys or less England & Wales and four storeys or less Scotland Timber Gable to Masonry fixing detail to cold roofs – raised gable wallplate

Cavity trays and firestops to be detailed by building designer Gable Panel

Breather membrane to face of gable panel

Insulation continued into gable panel

Cullen FT Timber frame wall ties Mortar bed Wallplate 38mm min- 75mm maximum depth Levels to be adjusted to ensure top of bracing inline with top of blockwork Cullen Gable Restraint Bracket (GRB) at maximum 750mm centres Cavity insulation shown for indicative purposes only - thermal bridging and SAP calculations to be plot specific

Roof insulation

Longitudinal truss bracing (depth can vary to suit blockwork level)

Level of truss wallplate

Solid blocking between truss and gable panel at horizontal restraint strap positions Gable Panel to wallplate fixing - Paslode 3.1mm dia x min 75mm long smooth shank nails at maximum 100mm centres Vertical holding down strap plugged and screwed to blockwork at maximum 1.8m centres, Cullen VRS-900-100

Cullen PFS-1500-100-B restraint straps fixed to longitudinal truss bracing / additional longitudinal bracing at maximum 1.25m centres with 8 no. 4 x 25mm steel screws

Gable Panel (with or without gable ladder)

Gable Panel (without gable ladder)

Truss profile

Cullen PFS restraint straps bedded in mortar joint between top of masonry and wallplate and fixed to longitudinal truss bracing maximum 1250mm centres with 8 no. 4 x 25mm steel screws

Bottom rail of gable panel

Continuous wallplate 38mm min-75mm maximum depth

1250mm max

Mortar bed

750mm max 750mm max 750mm max 750mm max

Cullen Gable Restraint Bracket (GRB) at maximum 750mm centres

Cullen VRS-900-100 fixed to top of bottom rail with 4 no. 3.4 x 35mm square twist nails

1800mm maximum

Vertical restraint strap plugged and screwed to blockwork at maximum 1.8m centres - Cullen VRS-900-100 installed to top of gable panel bottom rail

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The latest version of the technical guide will always be the digital format on our website.

Technical support: 01592 771132 / technical@itwcp.com / https://www.itwcp-offsite.co.uk 11

Brands for the offsite industry

Cullen Technical Support email: technical@itwcp.com

May 2024*

*Subject to change at discretion of ITW Construction Products Offsite

ITW Construction Products 1 Wheatstone Place Southfield Industrial Estate Glenrothes Fife KY6 2SW t +44(0) 1592 771 132 f +44(0) 1592 771 182 e orders@itwcp.com www.itwcp-offsite.co.uk

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