Cullen Restraint Straps Technical Guide 2025

Restraint Straps (Domestic Floors)

Perpendicular Restraint

Floor Level

Detail

Region

Ground Floor

1st Floor

2nd Floor

England & Wales

PFS required at 2m max centres

Perpendicular

PFS required at 1.25m max centres

Scotland

PFS required at 2m max centres

Please refer to page 4 for further information on PFS straps For all applications strap must extend over a minimum 3No Joists PFS surface fixed to I–Joist

— Noggins to be installed between the I-Joists or Metal Web Joists using 2No UZ-Clips and 2No. skew nails staggered either side — After fitting all noggins the PFS strap can then be located tight to the block work and centred on the noggins — The strap should be nailed with a minimum of 8No 3.4 x 35mm square twist nails evenly spaced and into at least every joist — — Noggins - NHBC Requirements — Width: min. ½ I-Joist depth, max. 150mm — Depth: min. 38mm — Timber: min. C16 grade

— Only suitable when joists line through with top of block work

PFS through web of I–Joist

— Cut a small slot in the I–Joist web, just under the top flange — Slide the PFS through the slots and position tight against the block work — To provide a fixing for the PFS, noggins must be nailed in place between the I-Joists through the I-Joist web — The strap should be nailed with a minimum of 8No 3.4 x 35mm square twist nails evenly spaced into the noggins

— Not suitable when joists line through with top of block work

Noggins - NHBC Requirements — Width: min. 38mm — Depth: min. ½ I-Joist depth, max. 150mm — Timber: min. C16 grade

PFS through web of Open Web Joist

— Strongback/Additional Noggins to be installed as per manufacturer’s guidelines — Position PFS tight to block work and centred on block — The strap should be nailed with a minimum of 8No 3.4 x 35mm square twist nails evenly spaced into the noggins

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

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