South Quay Plaza, Canary Wharf E14

FERBOX Reinforcement Continuity System

Former BBC Television Centre, White City W12

FERBOX Reinforcement Continuity System

Exchange Square, Birmingham

FERBOX Reinforcement Continuity System

Home | Product | FERBOX Reinforcement Continuity System

FERBOX Reinforcement Continuity System

FERBOX provides the continuity between wall and floor reinforcement. This continuity strip solution is manufactured to precise application requirements and is in daily use by the industry’s leading concrete frame contractors.

Invisible Connections’ manufacturing scope is unrivalled in this product sector, so engineers and contractors benefit from bespoke fabrication to site specific dimensions without the need for any on site modification. FERBOX customers can therefore have confidence that design intent and quality assurance will be met as well as timely delivery and ease of installation.

Good practice as standard practice

For design intent and construction practicalities to be achieved, as well as the quality assurance needs of professional stakeholders to be met, the UK concrete reinforcement sector adopts this process as standard:

  • Concrete reinforcement is specified (to BS4449:2005+A3:2016) and CARES approved.
  • ‘Cut and bent’ requirements are designed to a range of shape codes (BS8666:2005 refers) which provide the basis for designers to define all dimensions to the needs of each project.
  • After careful quantification, to avoid wastage, reinforcement is manufactured to order by CARES approved fabricators.
  • Bundled and uniquely labelled to aid installation, reinforcement is delivered on schedule to site.

This rationale also applies to threaded couplers.

Yet when it comes to reinforcement continuity strip, such checks are often inexplicably dismissed. What is more, since reinforcement continuity strip is subject to the additional demands of rebending on site, it should result in higher levels of scrutiny, not less.

If you would like to see our products in action, please have a look at our videos in the resources area.

Choose the appropriate Ferbox shape for your project requirements below. Alternatively, you can order multiple Ferbox shapes at the same time using our All Shapes Scheduling Form, which includes a guide to every shape option in the Ferbox range. Alternatively, download our Off the Shelf Scheduling Form.

FERBOX reinforcement continuity strip

FERBOX Reinforcement Continuity System
Enables uninterrupted construction of walls to full height. Easy, quick and reliable installation.


Pre-bent bars already spaced out in a fixed formation. Provides continuity of reinforcement across construction joints.

Choose Ferbox by application

All Specials Range

Specials Shape 21 Range

Specials Shape 11 Range

Specials Shape 00 Range

Specials Shape 13 Range

Specials Pull Out Links Range

Selecting the right product

Find below which Invisible Connections’ products are best suited for your project requirements, or download our at a glance Product Selection Guide to view the entire product range, features and benefits.


Off the shelf rangePopular shapes and sizes supplied in fixed length casings.Speed of delivery.
Specials rangePurpose made to application requirements.Reinforcement design requirements are met, without any cutting or wastage on site.
Bending toolsBending ToolsLong length to increase leverage.Safe method of straightening bars which helps ensure straightness or reinforcement at joint interface.
To make an enquiry, email [email protected] or [email protected] or talk to us by calling 01844 266000.

A structural component, not an accessory

Continuity strip is sometimes regarded as an insignificant ‘accessory’ and brought into the UK without any recognisable form of approval. Such products tend to be entirely ‘standard’ in their configuration, with a ‘one size fits all’ approach to anchorage, lap and casing length. Frequently proving to be wasteful in application, these products offer little to address the needs of reinforcement design.

However, CARES approved continuity strip manufacturers are adept at the timely fabrication of their products, accommodating principal design and construction practicalities.

Varying reinforcement and casing dimensions to suit, results in what we know as ‘specials’. For UK CARES approved fabricators, these variations are simply incorporated and help to ensure that design intent is met, whilst also making life much easier for contractors.

Quality assurance and compliance

Reinforcement continuity strips are important structural components which require performance validation. CARES Technical Approval provides this validation through a process of structural testing, regular mechanical testing and audit. This meets the quality assurance needs of professional stakeholders and enables compliance with the National Structural Concrete Specification (NSCS) published by Construct Concrete Structures Group.

‘Specials are our standard’

For good reasons over 90% of Ferbox reinforcement continuity strip is made-to-measure, which has many efficiency advantages for concrete frame construction. Here’s our top 10:

  1. Removes the labour and associated costs of cutting and re-sealing cases (also compromising lap-lengths, which are cut short)
  2. No material losses: on a typical project, we estimate that 20% of ‘standard’ cases and reinforcement are wasted.
  3. Wastage transfer and disposal is eradicated, saving cost and protecting the environment.
  4. Correctly sized casing lengths eliminates the unplanned and expensive cost of remedial couplers, drilling and resin-fixing rebar.
  5. No need to run power and power-tools, which improves efficiency.
  6. Health and safety conditions are improved, since there is no need to use power-tools.
  7. Specified reinforcement design can normally be met (achieving correct anchorage, lap and concrete cover).
  8. In congested site working conditions, the hassle is taken out of installation by transferring avoidable operations offsite, into factory controlled conditions.
  9. Deliveries can be scheduled on a just-in-time basis, minimising site storage requirements and making the location-labelled Ferbox easy to find.
  10. Product performance requirements are met: All Ferbox manufacture is endorsed by CARES Technical Approval, helping you to meet the requirements of the National Structural Concrete Specification (NSCS).


Can't find what you're looking for? Our resources area provides much more information. Or get in touch.


Related projects

If you would like to discuss your specific project requirements, please contact us for technical advice without obligation.

We hadn’t typically gone the ‘specials’ route before. But, by investing a little upfront time to schedule our FERBOX requirements, we gained a smooth supply and installation process – without wastage or complication – and exceeded the programme demands of our slip-formed cores.

Adrian Paul, Project Manager, O’Keefe Construction (Greenwich) Ltd 
Adrian Paul, Project Manager, O’Keefe Construction (Greenwich) Ltd

Invisible Connections are an outstanding company to work with. Between Ross in sales and Derek on the technical side of things, iC have an offering which the rest of the market would do well to get close to. I can’t credit these two individuals enough for the support they have given me for both standard and bespoke FERBOX connections – some rather more complex than others!

Iain Harding, Project Manager, Keltbray Structures 
Iain Harding, Project Manager, Keltbray Structures

© 2020 Invisible Connections Ltd | All Rights Reserved | Privacy Policy | Cookies

Invisible Connections, FERBOX and REDiBOX are registered trademarks

Our operational response to the Coronavirus
Following government guidance to ‘stay at home’ we are suspending our FERBOX manufacturing operation so that our factory workers can isolate at home in the same way as their administration-based colleagues.

FERBOX production will be mothballed from Wednesday 1st April 2020. We expect to be able to fulfil any existing FERBOX orders for delivery week ending 3rd April 2020 (if those construction sites remain open) but will decline any new orders unless they can be fabricated by close of business on Tuesday 31st March.

To be clear, although we’re suspending FERBOX production until further notice, our business will remain functional in all other respects. Our factory and offices will be largely unmanned, but we will be remote working from a sales, technical support and administration perspective. You can continue to reach us by phone, email or via the Contact us page on our web site. On an ongoing basis, we’ll be able to take orders and will have arrangements in place to despatch any stock items, including our ‘off the shelf’ FERBOX options, as well as our range of Telescopic Connectors and accessories.

Please accept our apologies if any of your projects which may remain open are inconvenienced, but we trust you'll understand our responsibility to balance the operational needs of our customers alongside the health, safety and concerns of our own workforce and to 'do our bit' however small, to help protect the community at large.
Thanks for signing up. You must confirm your email address before we can send you. Please check your email and follow the instructions.
We respect your privacy. Your information is safe and will never be shared.
This is a special one time offer!