TO ENSURE life safety and property protection, it is necessary for many construction products to be fire tested and certificated to meet the requirements of Building Regulations. As a consequence of this, manufacturers go ‘through the hoop’ to prove the performance of their products.
Installers have a role to play too; there is no point spending money on testing and certificating a product if it is installed by those without the technical ability to do so in a correct and safe manner. That is why many reputable installers – for example, all Association for Specialist Fire Protection (ASFP) installer members – are third-party certificated, in accordance with recognised schemes operating under the auspices of the United Kingdom Accreditation Service.
However, there are a number of questionable actions from self-promoting, self-inspecting suppliers/applicators, who are potentially undermining the established procedures for evaluating passive fire protection products used to ensure fire safety in buildings.
This article is intended to advise against such questionable installations and suspect installers. If there are any doubts about the veracity of claims made, professional advice should be sought.
Fire door concerns
In the UK, the Channel 4 TV programme, Property Snakes and Ladders, recently advised that ordinary timber doors could be converted into fire doors by the simple application of an intumescent coating to the surface. This was compounded by the implication, ‘why buy an expensive fire door?’
Unfortunately, this naively simplistic approach simply will not work for the vast majority of doors, adding just a few minutes to the fire-resistance time that a non fire door would achieve. Yes, it is possible to upgrade doors using a package of intumescent papers and paints, but only for doors that already have the potential to be fire doors.
A real fire door will have been tested in a standardised manner by a recognised fire test laboratory. The fire test report will limit the result to the tested construction with only minor variations. It is critical to recognise that the test applies to the entire door system (referred to as a ‘doorset’), which includes the building hardware, the door frame and the abutments, and that the result is limited to the physical dimensions of the doorset tested. Change any of these and the test evidence is no longer valid and is not applicable.
The outcome of the test is affected by many factors, such as:
• the type of wood from which the door is made and its density
• the thickness of the door leaf
• the structure of the door, including variations from any panelling
• the frame that encloses the door
• the building hardware and the gaps between the door, the floor and the frame
• any additional protection required for fixings and panelling
So, anyone tempted to ‘upgrade’ an existing ordinary door using one of these proprietary systems should think again. The supporting documentation should be checked very carefully to see if it applies to the door being upgraded.
Contrary to some opinion, these are not ‘do-it-yourself suitable’ products. We must call a halt to the unqualified application of intumescent coatings to any old door, and strictly observe the limitations in the documentation for any products that may have been tested on specific door assemblies.
Third-party product certification schemes for fire doors are operated by a number of providers. Details can be found at the following websites: www.bwf.org.uk, www.bmtrada.com/qmark, www.redbooklive.com, www.warringtonfire.net/certifire, www.ifccertification.com
Surface coatings
The internal surfaces of rooms and routes for means of escape in buildings have limitations on the spread of flame over their surfaces and on the amount of heat released when they are involved in fire. The fire performance recommendations of Approved Document B to the Building Regulations in England and Wales range from the highest performance, British Class 0 (European Class B-s3, d2), down to the lowest performance, British Class 3 (European Class D-s3, d2).
For painted (coated) surfaces, the ASFP has encountered various situations where purchasers are encouraged to apply ‘intumescent wallpaper’, or intumescent paints, to a variety of surfaces. Once again, if due regard to limitations in the fire test report are not taken into account, lives could be put at risk. Surfaces can be upgraded, but the results will depend on the materials, the substrates and exposure of the surface to be treated.
The ASFP provides useful advice for enhancing the fire performance of surfaces in buildings in Guidance on the classification for the reaction to fire performance of fire retardant coating systems (also known as the ‘Orange Book’), which can be downloaded free from www.asfp.org.uk/publications. European-based information will become available as ETAG 028: Fire retardant systems from www.eota.be
Over-cladding intumescent
For many reasons, it is often desirable to over-paint intumescent coating which may be providing fire protection to structural steelwork. While it may be possible to over-paint some specific types of intumescent coating system, the individual coating manufacturer should always be contacted for advice. Without such advice, over-painting is not recommended.
Where intumescent coatings have been applied as fire protection to steelwork, it may be desirable to install additional cladding over the steelwork, or in close proximity to it. The ASFP has published Technical Guidance document TGD 13: Over-cladding reactive coatings, which advises that a minimum gap of 50-times the dry film thickness of the reactive coating should be provided, to allow adequate expansion of the coating if exposed to fire. This advice applies to the flat surfaces and to the flange tips – unless specific test data proves otherwise for each steel section concerned.
Where the cladding is mounted onto continuous linear fixings or spacers made of timber or metal, the spacers should be considered to be a part of the main structure and be duly protected from fire, unless evidence can be provided to justify an alternative action.
Fire protection of steelwork
The ASFP guidance, Fire protection for structural steel in buildings (also known as the ‘Yellow Book’) has been the bible of established best practice for the fire protection of solid steel structural columns and beams since 1975. However, some advice is being revisited and reconsidered by the ASFP.
One example is whether the fire protection of circular or rectangular hollow steel sections should always be based on test data from ‘I’-shaped or ‘H’-shaped steel sections. Which tested configuration considers the worst case? New advice has now been published.
In addition, the ASFP has published three guides for the fire protection of structural steelwork on construction sites.
TGD 14: Code of practice – Boards for FP steelwork and TGD 15: Code practice – Sprayed non-reactive coatings for FP steelwork, cover the on-site application of boards and non-reactive sprays respectively. The third publication, TGD 11: Code of practice – Specification and onsite use of intumescent coatings for fire protection of structural steelwork, considers the issues of:
• surface preparation
• application procedures
• control and quality of site application
• factors affecting in service performance
• ease of maintenance
• repair procedures and standards of finish
• management considerations
• validation checklists
• quality plans and records
European fire test
Much of the fire test data and assessment in everyday use in the UK has been based on fire tests to BS 476-21: Fire tests on building materials and structures. Methods for determination of the fire resistance of loadbearing elements of construction, and assessed to agreed principles as published in the ‘Yellow Book’.
However, we are now entering a period where there are new kinds of historical test data at a European level. In previous years, the European standard ENV 13381-4: Test methods for determining the contribution to the fire resistance of structural members. Applied protection to steel members, provided a means of determining the contribution of fire protection systems when applied to structural steel. The document was due for review a number of years ago, and the review has now almost been completed. Old test data to ENV 13381-4 will soon become historic information.
New fire test and assessment details for the contribution to fire resistance of structural steelwork from reactive coatings are provided in BS EN 13381-8. Moreover, the publication of a revised BS EN 13381-4 will provide the procedures for boards and non-reactive sprayed systems. The ASFP ‘Yellow Book’ will be updated to reflect these changes when publication occurs.
Junctions between systems
The ASFP guidance TGD 08: Code of practice – Junctions between different fire protection coverings to steel outlines an important issue.
In simple terms, the actions required depend on which product was in situ before the additional system was to be added. Is an intumescent coating to be added next to a board, non-reactive sprayed coatings, or a different intumescent system? Or is the existing system based on intumescent technology and a different system to be installed? These issues are fundamentally important to a reliable installation. And, without taking suitable actions, any liability may be difficult to establish.
In addition, as set out in TGD 10: Code of practice – Refurbishment and upgrading fire protection of structural steelwork, the refurbishment process can take different directions, either as full replacement, partial removal/replacement, or removal and replacement with a different system.
Web openings
While the fire protection of solid steel structure has been well established over the years, new research data can sometimes challenge older practices – and this is now apparent for the use of intumescent coatings for the fire protection of ‘cellular’ beams with circular, lozenge, and/or rectangular web openings.
Because the residual steel post between separate web openings can have a different size and shape, the failure temperature and manner of failure in fire can vary as well. The ASFP has addressed this problem in Section 6 of the fourth edition of the ‘Yellow Book’. New information will be added to provide a protocol for the evaluation of systems suitable for beams with rectangular openings in the steel web.
It is important to recognise that any claims made for the fire protection of cellular beams requires the test and assessment protocol to be followed, so that multi-temperature analysis tables can be created for individual reactive coating systems – initially for beams with circular openings and then extended to include rectangular openings. The test data is only valid if the required test protocol has been fully completed.
Frequently-asked questions
Readers will often have specific application questions relating to intumescent coatings, such as:
• can intumescents be used to fire protect beams at the heads of compartment walls?
• what is the recommended treatment for steel brackets and angles?
• what clearance is needed for services through beams?
• what about different exposure conditions?
• can intumescent coatings be added over other types of built-in fire protection?
These and other frequently-asked questions and answers can be found at www.asfp.org.uk
In summary, reputable fire protection products should only be applied by reputable installers with independent third-party certification. First-party (self-) certification practices based on non-accredited arrangements should not be considered as a viable alternative.
All of our lives are threatened by those who give incomplete advice, or misapply data. The ASFP is committed to promoting the best practice use of passive fire protection products in providing life safety
Niall Rowan is technical officer with the Association for Specialist Fire Protection
All ASFP publications referenced in this article can be downloaded free from www.asfp.org.uk/publications