National testing standard for the UK, covering non-load-bearing elements such as doors. It is an ‘old’ standard, dating from 1987.


Typically, the requirements for fire resistant doors for fire prevention are contained in the following documents:

  • “Her Majesty’s Government, The building Regulations 2010, Fire safety, Approved document B – Volume 1: Dwellings”;
  • “Her Majesty’s Government, The building Regulations 2010, Fire safety, Approved document B – Volume 2: Building other than dwellings”.

At the bottom of the page you will find the 2019 versions for use in England. Both Appendix C talks about fire doors which can be classified according to EN13501 or BS 476-22. In the latter case doors will be referred to as FD (Fire doors) and FD xx S, where xx is the duration in minutes, S is the smoke seal according to BS 476-31.


Normally, to market products in the UK, It is necessarey a document called Assessment, which can be drawn up to say that doors tested for example in Italy according to EN1634-1 can also be defined according to BS EN 1634-1, or according to BS476-22. In some cases BS476-22 is even more stringent than EN1634-1. We had the case of an EI2 60 door, which we had to classify according to BS EN1634-1 and not according to BS476-22, as a thermocouple from the additional process had exceeded 180 degrees. In BS476-22, it is specified that any thermocouple that exceeds 180 degrees causes the test to fail, while in the European one it was precisely something more.


The Assessment may also contain extensions to the scope of the results, in some cases very similar to EXAPs. Previously, very imaginative Global Assessments circulated, following Grenfell and the Composite doors scandal, the yardsticks of judgement have become much narrower, moving closer and closer to the rigour of the European standard.


 The Assessment is a document that is normally valid for 5 years. At Chemolli Fire we have both carried out tests directly in the UK and had tests carried out in Italy recognised, as well as renewing documents and agreeing with the laboratory that provide extensions to the existing scope of results.


In the UK there are several voluntary quality marks, so-called ‘third party certification‘, such as BM Trada, Certifire, and others. Although these are not compulsory, they are often referred to in tender specifications and thus become mandatory.


The English proposal for CE national marking, maybe over the time we will see how much it takes hold.


The situation we report is a – geopolitical – very fluid and evolving picture. Remember that with 31.12.2020 the BREXIT will come to an end, with or without agreement, so we do not know if what we are reporting here will remain valid and for how long. We can assume a push for the use of BS476 standards over EN1634, a tightening on the possibilities of Assessments, a greater demand for Third Party Certification and, last but not least, UKCA.


Let us discuss BS476-22 with reference to EN1634-1, identifying the primary differences between the test standards.

BS 476-22: 1987 and BS EN 1634-1, although conceived independently, have many similarities as they share a common reference document.

ISO 834 defines the cellulosic fire curve, providing the common ground for many national fire resistance test methods for doors within the European Union.

The new European test method meets the functional requirements of all EU member states and introduces new methodologies to ‘harmonise’ the potentially different behaviour of existing fire test furnaces.

Changes introduced in the new standard include the specification of the furnace wall cladding for fire tests and the level of oxygen present during the tests. However, three changes have been shown to significantly affect the performance of the doors under test. These are:

  • temperature control and monitoring devices
  • furnace pressure regime during the test
  • requirement to cycle the doors prior to fire testing

Temperature control and measurement devices. Both test methods require the temperature of the furnace atmosphere to be monitored during the test. This allows the temperature to be controlled according to the time/temperature curve specified in the relevant standard.

The temperature inside the furnace is measured by ‘type K’ thermocouples. BS 476-22 requires the use of a 1.5 mm probe thermocouple while BS EN 1634-1 requires the use of the ‘plate thermocouple’. Physical differences between measuring devices result in significant differences in their response to temperature increases. The 1.5 mm probe type thermocouple (BS) has a very small mass that responds directly to changes in gas temperature – very low thermal inertia, i.e. a very fast response. The plate thermocouple device (BS EN) uses a 1 mm thermocouple to monitor the temperature of a steel plate that has been heated by furnace gas. It takes much more thermal energy to heat the steel plate than to heat the 1.5 mm probe tip. As a result, the plate thermocouple is said to have a higher thermal inertia and consequently a slower initial response rate.

In short, it is like having a car odometer with a weighted needle: since gas is put into the oven to create heat with the flames, by having an instrument that is faster at reading the temperature, I will put less gas.

In short, it is like having a car odometer with a weighted needle: since gas is put in the oven to create heat with the flames, having an instrument that is faster at reading the temperature, I will put less gas.

How can this difference affect the test?

In the first ten minutes of the BS EN test, the oven actually runs between 10 and 34% more than the equivalent test performed to a BS 476-22 standard. This ten-minute period is the time that it takes to overcome the initial thermal inertia of the plate. After ten minutes, the two devices show very similar temperatures.

Oven pressure regime

The pressure regime inside the oven is crucial for the behaviour of the door under test. The positive pressure inside the oven pushes hot gases out of the oven chamber through any gaps in the sample. It is this effect that make the need fall for heat-expanding perimeter seals for doors.

The difference between the two standards lies in the height at which the neutral axis is placed, i.e. where the transition from positive to negative pressure inside the oven takes place. The transition point is at a differential pressure of 0 Pa and is known as the neutral pressure axis. In BS 476-22 this is set at 1 m above the threshold, in BS EN 1634-1 the value is set at 500 mm above the threshold.

This leads to a different pressure pattern with impact in the behavior of the sample seals.

Our experience

Considering 20 or 30 minute doors, if the test is 30% easier, you could make doors that cost 30% less.

This is not really the case, because fire doors are not sized like ham at the delicatessen shop. It is much better to leave a few extra slices!

As the minutes go by, this difference becomes smaller.

These considerations obviously do not apply to tests using plate thermocouples or combined EN+BS tests, where the more restrictive parameters would apply.

Exposed side

Tests in BS476-22 have often been carried out on one side only. Since the ‘composite doors’ scandal we have seen a rush to test from two sides, also in accordance with the Ministry of Housing, Communities and Local Government circular of 31 July 2018.


If we are talking about CE-marked doors, the marking allows marketing in the states of the Union. Check whether the mandatory characteristics for the target country are met and that the documentation is in the language of the country where they are marketed. For more information on marking, go to the CE MARKING section of our website.(CE MARKING).

Clearly, approval can only be applied for under certain conditions if the test was carried out in BSEN1634-1 and not BS476-22.


When it comes to testing, we provide our experience and our KNOW-HOW.

As specialists, we offer comprehensive advice during all stages of laboratory testing, from design to documentation of results.


Listening is the most important phase of our interaction: we want you to develop a product that is the sum of your identity and needs.

First, we try to understand your real needs, the channels and markets you want to measure yourself against.

Then we show you how the testing and certification process takes place: we need to engage with you, to fully grasp your point of view. Then we develop a proposal that respects – compatibly with the required performance – your product lines, your production lines and, as far as possible, potential economies of scale using products and methodologies already established in your company.


Beyond the opportunities, which we will illustrate to you, we will then advise you on what we would do in your position.

We will advise you with our experience on what, how and where to test. In which laboratory to test? In the one best suited to your needs.


Once the key has been turned, we prepare a project that is comprehensive in all details. Which materials and components to use, an important part of our dialogue on which we can best advise you. In addition to this, a cost sheet and a weight forecast, to allow you to check whether your goals will be achieved. Using industry best practices, we are convinced of this.


A consultants we give advices, then we leave it to the client to put it into practice. We are not like that: we take off the tie and put on our work clothes when needed. We launch the production of the samples, we are present during the gluing of the doors, we offer support during the process and shoeing, we proceed with our technicians to the installation of the samples in the laboratory and we are physically present at the testing. We manage the post-test documentation review phase, explain the documentation to you and remain available for all issues related to results management.


In addition, we offer you comprehensive consultancy during all stages of certification, assisting you:

  • in the planning and budgeting of activities, to determine an investment plan;
  • During all the communication with the notified body;
  • during sampling (withdrawing products for testing);
  • in implementing your FPC – Factory Production Control;
  • In preparing the necessary documentation including instructions and labels;
  • with our presence during initial inspections;
  • afterwards, as support for all management issues.