A fire-rated steel and glass door is only as good as the evidence behind it. Fire door testing and certification determine whether a doorset can legally carry a classification like FD30, E30 or EI30 — and understanding how that evidence works helps you ask the right questions before you buy, install or modify a doorset. This guide walks through fire testing, assessments, third-party certification and the documentation you should expect to see for any fire-rated doorset.
Want to check the evidence behind a specific doorset? Get in touch and we’ll talk you through what applies to your project.
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What Is the Difference Between a Fire Test and a Fire Door Assessment?
What Is a Field of Application (FOA) and Why Does It Matter?
What Documentation Should I Ask For When Buying a Fire-Rated Steel and Glass Door?
What Is Third-Party Certification for Fire Doors?
Do Fire-Rated Steel and Glass Doors Need CE or UKCA Marking?
What Standards Apply to Fire-Rated Steel and Glass Doors?
Can a Fire Door Be Certified If Only the Glass Has Been Tested, Not the Whole Doorset?
What Happens If a Fire-Rated Door Is Modified After Installation?
How Do I Check If a Fire Door Certificate Is Genuine and Up to Date?
A fire test and a fire door assessment are both legitimate forms of fire-performance evidence, but they work in different ways.
A fire test involves physically exposing a full-size doorset to a furnace under controlled conditions at a UKAS-accredited test facility, then recording how long it maintains its integrity and, where relevant, its insulation performance. This produces a test report specific to that exact door configuration.
A fire door assessment, on the other hand, doesn’t involve a new physical test. Instead, a suitably qualified fire engineer uses existing test data — often from a related but not identical doorset — to make an evidence-based judgement about how a variation would likely perform. Because assessments extrapolate from real test data rather than assuming performance, they’re a widely accepted part of the fire industry, provided they’re carried out by a competent, appropriately qualified assessor.
In short, one is direct physical evidence and the other is expert interpretation of existing evidence — and a compliant doorset can rely on either, depending on its configuration.
Field of Application (FOA) defines the range of variations that a single fire test’s results can legitimately be extended to cover, without requiring a brand-new test for every possible size or configuration.
Since it’s not practical to test every conceivable size, glazing option and hardware combination, an FOA sets out the boundaries — for example, the maximum and minimum door sizes, permitted glazing types, or hardware options — that remain valid based on the original test evidence. As long as a doorset stays within its FOA, it can rely on the original test without needing separate evidence for every variation.
This matters because a doorset that falls outside its tested FOA needs its own supporting assessment or additional test evidence — you can’t simply assume a small change in size or configuration is automatically covered.
Before you buy, always ask for documentation that covers the complete doorset, not just the glass or the frame in isolation.
At minimum, this should include:
Importantly, a product brochure, website description or verbal assurance isn’t sufficient evidence on its own — you need traceable documentation that ties your specific doorset back to genuine test or assessment data. If a supplier can’t readily provide this, treat that as a red flag rather than an oversight.
Third-party certification is an ongoing, independently audited scheme that goes beyond a single test report, giving continuous assurance that a manufacturer’s production still matches what was originally tested.
Rather than relying solely on a point-in-time test result, third-party certification schemes typically involve regular factory audits, product sampling and surveillance to confirm that doorsets leaving the factory still match their original test evidence. As a result, this type of certification adds an extra layer of confidence for specifiers, because it addresses ongoing manufacturing consistency, not just the performance of the single doorset originally tested.
If a specific certification scheme matters to your project, always confirm directly with your supplier which scheme (if any) applies to the exact doorset you’re specifying, since coverage can vary between product ranges.
Whether CE or UKCA marking applies depends on the specific product, the standard it’s tested against, and the market it’s being sold into — it isn’t a blanket requirement for every fire door sold in the UK.
Where marking does apply, it relates to a manufacturer’s declared conformity with a specific harmonised standard, rather than replacing the underlying fire test or assessment evidence for the complete doorset. In other words, marking and fire test evidence answer different questions, and neither one substitutes for the other.
Because marking requirements can be product- and standard-specific, always check directly with your supplier whether it applies to the doorset you’re specifying, rather than assuming it either does or doesn’t.
Fire doors in the UK have historically been tested to BS 476 (the older British Standard testing method), while BS EN 1634 is the newer European test standard now widely used for fire resistance testing of doorsets.
Which standard applies to a particular doorset usually comes down to when and how it was originally tested, since older test evidence may predate the introduction of the European standard. Both standards can produce valid fire-performance evidence, but the specific classification and test conditions differ between them, so it’s not always straightforward to compare results across the two directly.
If you need to confirm which standard underpins a specific doorset’s evidence, ask your supplier directly — this is one detail worth clarifying rather than assuming.
Fire doors in the UK have historically been tested to BS 476 (the older British Standard testing method), while BS EN 1634 is the newer European test standard now widely used for fire resistance testing of doorsets.
Which standard applies to a particular doorset usually comes down to when and how it was originally tested, since older test evidence may predate the introduction of the European standard. Both standards can produce valid fire-performance evidence, but the specific classification and test conditions differ between them, so it’s not always straightforward to compare results across the two directly.
If you need to confirm which standard underpins a specific doorset’s evidence, ask your supplier directly — this is one detail worth clarifying rather than assuming.
Modifying a fire-rated door after installation can invalidate its certification, even when the change looks minor.
Drilling for new hardware, adding vision panels, repainting with an unapproved product, or replacing seals with a different type can all affect how the doorset performs under fire conditions — because each of these actions changes something the original test or assessment evidence relied on. As a result, a doorset that was fully compliant when installed can lose that status through work carried out afterwards, sometimes without anyone realising until it’s checked.
Because of this, always check any proposed modification against the doorset’s original evidence (or with the original supplier) before carrying it out, rather than assuming a small change won’t matter.
You can verify most fire door certificates by checking the certificate number against the issuing body’s own records, rather than relying on the document alone.
Many certification and test bodies maintain online registers or offer a verification service, allowing you to confirm that a certificate number is genuine, current, and actually relates to the doorset in front of you. This step matters because a certificate can become invalid over time, or may not match the exact doorset it’s being presented alongside.
If you’re ever unsure, contact the supplier directly and ask them to confirm the certificate against your specific doorset — a legitimate supplier should be able to do this without hesitation.
| Term | What it means |
|---|---|
| Fire test | Physical furnace test of a full-size doorset at an accredited facility |
| Fire door assessment | Expert judgement extrapolating from existing test data |
| Field of Application (FOA) | Range of sizes/configurations a test’s evidence can cover |
| Third-party certification | Ongoing audited scheme confirming production matches tested evidence |
| CE/UKCA marking | Declared conformity with a specific standard; not a substitute for doorset test evidence |
| BS 476 / BS EN 1634 | Older British and newer European fire test standards |
Every doorset we supply is backed by evidence for the complete assembly, not just the glass or frame in isolation. Speak to our team if you’d like to see the documentation behind a specific fire-rated steel and glass door before you specify or buy.
Published by Doors of Steel
Specialists in internal steel and glass doors and fire-rated steel door systems.
Last reviewed: September 2026
ON THIS PAGE
Choose From Topics Below
ON THIS PAGE
Choose From Topics Below
What Is the Difference Between a Fire Test and a Fire Door Assessment?
What Is a Field of Application (FOA) and Why Does It Matter?
What Documentation Should I Ask For When Buying a Fire-Rated Steel and Glass Door?
What Is Third-Party Certification for Fire Doors?
Do Fire-Rated Steel and Glass Doors Need CE or UKCA Marking?
What Standards Apply to Fire-Rated Steel and Glass Doors?
Can a Fire Door Be Certified If Only the Glass Has Been Tested, Not the Whole Doorset?
What Happens If a Fire-Rated Door Is Modified After Installation?
How Do I Check If a Fire Door Certificate Is Genuine and Up to Date?
Fire-door requirements are project specific. Information within this Knowledge Centre is intended as general guidance and should not replace the project’s fire strategy or advice from the responsible architect, fire engineer, Building Control professional or other competent person.
