Hi-Vis Gripper Technical Guide Innovation in Every Connection. Trust in Every Build.
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HV–GR Hi–Vis Gripper
The Hi-Vis Gripper is a build-in detail for I-joists into masonry reducing air leakage at the joist end. The Hi-Vis Gripper can be used on both external and party walls. Features & Benefits — Range of striking colours and unique design enables high visibility for post installation inspection — Bend and push fit with no mortar to front face speeds up install — Easy to install – no nailing required or need to trim joists to fit, saving time on site — Mastic not required to seal I–Joist perimeter, reducing site costs — Suitable for joists with either 90 or 100mm bearing without protruding into cavity — A major contribution to compliance with air leakage — Optional fixing for added security
Patent Number GB2511155
HV–GR–1 38 – 53MM WIDE
Build–in Detail Advantages (Requiring external mortar sealing only) — In line with existing building practice — Easy access — Quick and effective — Visual quality check from outside
HV–GR–2 58 – 72MM WIDE
Optional fixing point to secure HV-GR
Approvals — Meets NHBC technical requirements — Part E: Compliant with the requirements of Appendix A of the Robust Details Part E Handbook — Assessed to BS ISO–TR12470:1998 for 60 minute fire requirements
HV–GR–3 89 – 97MM WIDE
Material Specification High density Polyethylene
Additional parallel and perpendicular restraint may be required. Please refer to pages 129 – 130 for further guidance on built in restraint.
Available Sizes
Joist Width (mm)
Flange Depth (mm)
Joist Depth (mm)
Joist Manufacturer
38 – 53
58 – 72
89 – 97
220 245 300 220 240 300 220 240 300 220 240 300
HV–GR–220–1 HV–GR–240–1 HV–GR–300–1
HV–GR–220–2 HV–GR–240–2 HV–GR–300–2
HV–GR–220–3 HV–GR–240–3 HV–GR–300–3
James Jones (JJI)
45
HV–GR–240–1 (36mm) HV-GR-240-1 (36mm) HV–GR–300–1 (36mm)
HV–GR–240–2 (36mm) HV-GR-240-2 (36mm) HV–GR–300–2 (36mm)
HV–GR–220–3 (39mm) HV–GR–240–3 (39mm) HV–GR–300–3 (39mm)
Metsawood (FJI)
36 & 39
HV–GR–220–1 HV–GR–240–1 HV–GR–300–1 HV–GR–220–1 HV–GR–240–1 HV–GR–300–1
HV–GR–220–2 HV–GR–240–2 HV–GR–300–2 HV–GR–220–2 HV–GR–240–2 HV–GR–300–2
HV–GR–220–3 HV–GR–240–3 HV–GR–300–3 HV–GR–220–3 HV–GR–240–3 HV–GR–300–3
Steico (SJI)
39
Masonite (H, HB, HI, HL, HM)
47
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
Features & Benefits
Easily identifiable for post installation inspection
Meets relevant requirements and certification - NHBC, BBA, UKCA & CE
Force fit installation (no nails or mastic sealant required , or need to trim joists to fit)
Fire tested up to 60 mins In compliance with approved document B
Meets the sound requirements of a proprietary joist cap as specified by Appendix A, Robust Details Part E Handbook
Compliance Part L air tightness requirements - 68% more efficient than NHBC end seal detail requirements
1.02 m3/h
(+209%)
0.33 m3/h
New Cullen Hi-Vis Gripper
NHBC detail with mastic (minimum requirement)
To find out more about the features and benefits please scan the QR code to our new HV-GR features and benefits video Features & Benefits Video
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
Installation Instructions
1
2
Fold the HV-GR to create a spine and a gap between the two halves
3
4
Slide the HV-GR on at an angle and apply some pressure to bend the bottom tabs
From here push evenly on HV-GR to slide it onto the joist
5
6
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
Installation Instructions
7
8
HV-GR has been installed onto the joist and is ready for the mortar and blockwork to be added to finish the installation
Single joist Installation Video
Double joist Installation Video
Triple joist Installation Video
Scan the QR code to see our new single joist HV-GR installation video
Scan the QR code to see our new double joist HV-GR installation video
Scan the QR code to see our new triple joist HV-GR installation video
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
Improved Site Practice
90mm Min.
Suitable for joist with either 90 or 100mm bearing. Approved Document A Structure states – Tension straps need not be provided: A. in the longitudinal direction of joists in houses of not more than 2 storeys, if joists are not more than 1.2m centres and have at least 90mm bearing on the supported walls”
90mm Min.
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
Double / Triple joist application When installing double joist impossible to mortar fill between the joists creating an air passage, where the HI-VIS Gripper air tightness achieved by mortar to cavity face.
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
HV-GR | Optional Fixing In adverse weather or during transport, the HV‑GR may loosen. An optional fixing can be used to secure it to the joist end. Position the fixing on the marked ‘X’ , 20mm from the joist end, and ensure its diameter does not exceed 3.5 mm. Care should be taken to ensure the fixing does not protrude excessively on the opposite side of the joist. See installation details below.
Fixing options
Screws - (length 16mm)
Staples
*The fixing can be used to secure one side of the HV‑GR or both.
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
HV-GR | Optional Fixing
Fixing from both sides
Position a fixing above the ‘X’ on one side; on the opposite side, place a fixing below the ‘X’. This ensures a 20mm edge distance from the end of the joist is maintained.
Above ‘X’
Below ‘X’
End View
*The fixing can be used to secure one side of the HV‑GR or both.
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
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Cullen Technical Support email: technical@itwcp.com
July 2026*
*Subject to change at discretion of ITW Construction Products Offsite
Cullen Technical Guide
1 Wheatstone Place Southfield Industrial Estate Glenrothes Fife KY6 2SW t +44(0) 1592 771 132 f +44(0) 1592 771 132 e IQS-glen@itwcp.com https://www.itwcoe.com
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