Bi-directional fire testing of fire doorsets

In a fire door test, the complete door set should be tested from both sides; the inward and the outer faces to satisfy Building Regulations. This bi-directional test is aimed at replicating a building fire attacking the door from either direction – the opening-in or opening-out door face. Simulating a fire attack from either side of any doorset design requires testing two intact samples of each model.

Do all fire doors need to be tested on one or both sides?
The only exception to the bi-directional fire testing requirement given in Doc B, Appendix C, of the Building Regulations is elevator lift doors, which can be fire tested on just the lobby side.Can a doorset not just be fire tested from its most onerous direction?There is an argument for only testing timber fire doors from one side; this is based on observations that doors usually fail sooner when exposed to the fire on their opening-in side (pull side). The premise is that wood panels curl towards the heat, either pulling the edges away from the door surround (making an air gap), or into the door jamb (tightening the seal). So if it passes on its most onerous side then it can be deemed sufficient for fire-rated classification by the testing expert’s opinion on the evidence presented.  However, some authorities argue that this provision has allowed assumptions to creep into life-critical safety compliance testing whilst others claim that testing every timber door specification bi-directionally is only reaffirming what has already been proven.Certification bodies can legitimately apply evidence of previous specific tests on door components to make a Classification Without Further Testing (CWFT). For instance, the upgrade of fire-rated door hardware might widen the scope of an existing FD certification, so that the revised (improved) design is approved without further physical tests having to be undertaken.

 

The investigations conducted following the tragic Grenfell Tower fire resulted in a culture change across the building safety world. Some fire-rated composite doors were found to be sub-standard, when tested by a government body. This understandably raised a debate around the physical test procedures, and whether a reliance on older test evidence and assumptions accrued over the years might be allowing a gap between reality and theory to form.The divergence from the bi-directional text of Approved Document B, plus the standards BS 476:1987 and BS EN 1634-1:2014 was flagged up in circulars from the Ministry of Housing sent to Building Control Inspectors and certification test houses. When the Ministry conducted bi-directional tests on supposed fire-rated doors from six composite door manufacturers, five of them failed the minimum 30 minutes test. It was specifically pointed out that testing was all too frequently being conducted on a single side of the door, and test evidence was not being checked carefully enough for bi-directional compliance.“Most door sets are not truly symmetrical and as such, testing on both sides is necessary to demonstrate compliance with the approved document.” MHCLG (letter from Bob Ledsome, Building Safety Portfolio, July 2018 to Building Inspectors)

Is single-face testing still possible on symmetrical doors?
For door-sets that are truly symmetrical, there is still provision in EN1634-1 to test on one-side only. A truly symmetrical door doesn’t have an inside and outside face, as that by definition is asymmetrical. Also, as the installed door set is part of the fire door test certification, the presence of a door jamb or off-centre seals would entail testing each side for fire resistance, unless the tester can use their expert opinion to justify classification without a physical fire test.Bi-directional swing doors might be symmetrical if their structure is uniform, and they have identical hardware and fixings on either side. In other words, a fire testing lab couldn’t tell one side from the other even after seeing the construction details.

Key:

1. Frame, 4. Door leaf (core), 5. Glass, 6. Glazing bead,  13. Intumescent Fire & smoke seal, 15. Intumescent fire seal, 25. Glazing intumescent seal

Use of previous test evidence to negate bi-directional testing
If there is evidence that all components have been bi-directionally tested previously, a certification body may be able to classify the fire door without further testing. However, due to the increased scrutiny and guidance from the authorities, test laboratories must be exceptionally thorough in their review of the evidence submitted. This extra due diligence has resulted in previously issued evidence being rejected at subsequent audits, resulting in door manufacturers having to submit new samples for full bi-directional testing, with all the associated extra costs and time delay. Whilst the historical testing of timber firedoors is well documented and understood, new composite door materials have much less previous evidence to rely on, so doors made of such materials will usually require more stringent physical testing. 

What Doc B states about bi-directional testing of fire doors.
Since 2017, both the Government and the Fire Safety Industry have taken a much more stringent and thoughtful approach to fire safety in building infrastructure. This has resulted in a much-needed culture change across the building industry and supply chain, plus a number of amendments to UK Regulations, with the latest addition being the the Fire Safety (England) Regulations 2022.  The Building Regulation’s Approved Document B (Fire Safety) was amended in December 2022 – it still maintains that Fire Doors should be tested from both sides.

Where does it say in building regs that you should do bi-directional fire testing?
The requirement for bi-directional testing of fire-rated doors has always been specified in the current Approved Document B of the Building Regulations 2010. Appendix C (fire doorsets), section 3 states:“The requirement is for test exposure from each side of the doorset separately.”The only exception to this is elevator lift doors, which can still be tested from the outer side only.Where a testing house uses historical bi-directional test data to forgo testing the “less onerous” side of a fire door, they must consider uncertainties around new manufacturing techniques, modern composite materials and advances in engineered timbers.  As doorset manufacturers rightly strive for more sustainable, more secure FD designs, it cannot be assumed that fire performance will remain a constant.   Advanced composite construction materials and innovative designs have improved fire-doors in many ways – mobility access, security, energy-saving etc. – but there are calls for increased testing parameters to reflect worst-case scenarios, more realistic and ‘as-built’ conditions. Where CWFT (Classification without Further Testing) is used to justify not physically re-testing, this should be carefully scrutinised against the available evidence, and all implications of the complete installation considered.At Rutland, we are passionate about life safety in our industry and achieving compliance is an absolute necessity. Over the years, we have gained considerable experience in the incorporation of fire door closer controls and fire-door hardware in testing regimes, and we are always happy to share our knowledge – we regularly help doorset manufacturers meet ever-increasing levels of fire safety legislation and specifier expectations. Please don’t hesitate to get in touch if you think we can help.