A fire door is only a fire door if the whole assembly was tested and is installed as tested. That is why certification attaches to the doorset rather than to the leaf alone, and why a certified leaf hung in an uncertified frame with the wrong hinges is not a certified fire door however good the paperwork on the leaf is.
What is certified
Certification covers the complete assembly: leaf, frame, intumescent and smoke seals, hinges, closer, latch, glazing and any air transfer device, in the configuration that was tested or assessed. Substituting any of those for something outside the certification scope invalidates it. That is the single most common way a compliant door becomes a non compliant one, usually with an ironmongery change nobody recorded.
Labels and plugs
Certified doors normally carry a label or a colour coded plug, commonly on the top edge or the hinge edge, identifying the manufacturer, the certification scheme and the rating. Different schemes use different colours, so the colour identifies the scheme rather than being a universal code. Finding no label does not prove a door is not fire rated, but it does mean nobody can prove that it is, which amounts to the same thing at an inspection.
The installation certificate
Certification of the product says the door can perform. An installation certificate from a competent installer says this particular door was fitted as tested, in the right frame, with the right gaps, ironmongery and seals. Third party certification schemes for fire door installation exist for this reason, and the certificate is what a responsible person should be asking for at handover along with the product documentation.
Keeping the evidence
For new work, the Building Regulations require fire safety information to be given to the responsible person at completion, and the door documentation belongs in that package. Keep it with the fire risk assessment rather than in a site file that disappears with the contractor. Reconstructing a door's provenance years later usually costs more than a survey and sometimes cannot be done at all.
Questions people ask about fire door certificate
Where is the label on a fire door?
Usually on the top edge or the hinge edge, as a label or a colour coded plug identifying the manufacturer, scheme and rating. Look at the top edge first, with the door open.
Does a fire door certificate cover the ironmongery?
Certification covers the tested assembly including hinges, closer, latch, seals and glazing. Changing any of those for something outside the certification scope invalidates it.
What should I get when fire doors are installed?
The product certification, an installation certificate from a competent installer, and the fire safety information the Building Regulations require to be handed over at completion.