There is sometimes confusion over what a notional fire door is; 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 upgraded?
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 the UK government, is a fire door that satisfied the standard applicable to fire-resisting doors at the time of the building’s construction. 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 UK government advice is quoted, this refers to the document ‘Fire safety in Purpose Built Blocks of Flats’ section 62.12 to 62.23. 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. In 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 goes into detail on this subject.
Timber-based fire doors are generally rated from FD20 to FD120 – that’s 20 minutes to 120 minutes of fire resistance. However, this is a benchmark from the fire resistance performance tests and 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 protection and reducing the spread of fire. This should be noted in the fire risk assessment for the building and acted on accordingly.
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 it 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 undertake the necessary repair and improvement works using the correct materials. In this way, there can be some assurance that it 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 work 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 on the website of the Intumescent Fire Seals Association including Information Sheet 6: ‘Guidance on the Upgrading of Joinery Doors’ 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, we 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 external or internal 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 subjected to the upgrading works. It will also depend on the competence of those that carry out the work and the quality of the workmanship regarding the fire door installation. The correct selection of door hardware will also contribute to the fire performance of a timber-based door.
Fire Doors Complete is based in Leicester business premises and has years of experience working with timber-based fire doors and fire safety regulations in Leicestershire, Derbyshire, Nottinghamshire and beyond. We aim to help make every building safe and legal and run a variety of training programmes to help educate fire door installers, maintainers, inspectors, property owners and building operators about the legislation surrounding fire doors in the UK.
We work with joinery companies, door fabricators, housing associations, builders, installers, landlords, facilities maintenance companies and healthcare and education institutions to help ensure fire door safety compliance, and provide high levels of customer satisfaction according to our reviews.