By Neil Ashdown CertFDI, FSIDip
There is sometimes confusion over what is a notional fire door, is it the same as a nominal fire door and can fire doors be upgraded?
In this blog, we will look at these terms to provide some much-needed clarity.
First, what do we mean when we use the terms Nominal, Notional and Upgrading?
A ‘nominal’ fire door is a timber-based fire door that, in the opinion of the fire door inspector, can provide fire resistance performance for a specified period of time.
A ‘notional’ fire door, according to advice by UK government, is a fire door that satisfied the standard applicable to fire resisting doors at the time the building was constructed. This type of door may not have been fitted with intumescent strips and smoke seals.
According to the same UK government advice, an ‘upgraded’ fire door is a notional door that has been upgraded by fitting, for example, intumescent strips, smoke seals and a protected letter box.
Where I have quoted UK government advice, this refers to the document ‘Fire safety in Purpose Built Blocks of Flats’ section 62.12 to 62.23. You can find this document at https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/994149/Fire_Safety_in_Purpose_Built_Blocks_of_Flats_Guide.pdfhttps:This is the document referenced in the government’s advice note ‘Annex A – Advice for Building Owners on assurance and assessment of flat entrance fire doors’ from January 2020, which tells us that composite fire doors cannot be considered as ‘notional’. You can find this document at https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/859279/Annex_A_-_Assurance_and_Assessment_of_Fire_Doors_-_January_2020.pdfhttps://assets.publishing.service.gov.uk/government/uploads/systeIn terms of nominal fire doors, there is little in the way of advice but a competent fire door inspector should be able to provide guidance and the Safelincs website at https://www.safelincs.co.uk/nominal-fire-doors/ goes in to detail on this subject.
Door fire ratings
Timber-based fire doors are rated, generally, from FD20 to FD120, that’s 20 minutes to 120 minutes fire resistance. However, these are a benchmark from the fire resistance performance tests and the fire door rating is an indication of fire performance, not necessarily how a door would perform in a real fire.
It is important to understand that nominal fire doors and notional fire doors are not the same as fire doors that carry evidence of fire resistance performance or a certificate of approval. Nominal fire doors and notional fire doors carry no such assurances. Therefore, such doors carry a greater risk in terms of their fire performance than that of fire doors with evidence of fire resistance performance. This should be noted in the fire risk assessment for the building and acted on accordingly.
Upgrading fire doors
So, we are now clear that a notional fire door is just that, notional, based on a theory. A nominal fire door has no evidence of fire resistance performance so we rely on the opinion of the inspector or assessor in terms of its likely performance.
What about upgraded fire doors, is there any evidence of fire performance for them? The answer of course is yes and no.
The extent of the upgrading works and the original condition of the door will affect the performance of the door in a fire. In the case of the nominal fire door, the core construction of the door could be the same as that of a fire door that carries evidence of fire performance so provided that the door is in a satisfactory condition adding suitable intumescent seals, smoke seals and a self-closing device will improve the fire performance of the door.
However, taking a lightweight door that has thin panels or boards and adding the same seals and self-closer as described above will not turn that door into a fire resisting door. That type of door is unsuitable for upgrading to a fire door.
The key to upgrading a fire door is to assess the door for suitability and condition and then to undertake the necessary repair and improvement works using the correct materials. In this way there can be some assurance that the door would perform as a fire resisting door. In terms of what form that assurance takes, this will depend on the availability of evidence of performance for the materials used for the upgrading works. It will also depend on the competence of those that carry out the works and the quality of the workmanship.
Upgrading of suitable doors to fire doors has been accepted as a useful way to make buildings safer for some time now and there are guidance documents to help those that need to undertake these types of upgrading projects. These documents include those from Historic England; ‘Timber-panelled Doors & Fire’ from 1997 and the ‘Guide to the Fire Resistance of Historic Timber Panel Doors’ published in July 2021. There is also guidance at the website of the Intumescent Fire Seals Association including the Information Sheet 6: ‘Guidance on the Upgrading of Joinery Doors’ at https://www.ifsa.org.uk/documents/ and the wood information sheet WIS 1-32 ‘Upgrading timber joinery doors for fire resistance’ available from TRADA.
So, in terms of evidence of fire performance for upgrading doors I said earlier ‘yes and no’ to the question of whether such evidence is available. Yes, there are tested products with evidence of fire performance for use when upgrading doors to fire doors. Such products include intumescent paints, intumescent paper and fire rated boards as well as intumescent edge seals and smoke seals but these are not standalone fire rated products. They will have been successfully tested when applied to certain types of timber doors so it is important to make sure that the test evidence for the product is applicable to the type of door being subject to the upgrading works. Also, as already stated, it will also depend on the competence of those that carry out the works and the quality of the workmanship. The correct selection of door hardware will also contribute to the fire performance of a timber-based door.
Neil Ashdown is managing director of Fire Doors Complete Ltd. He is a former manager of the Fire Door Inspection Scheme (FDIS) and provides consultancy, survey, inspection and training services in respect of fire doors and escape doors. If you require assistance with upgrading of fire doors, including at listed buildings, please contact me via https://www.firedoorscomplete.com