There are two ways to buy a fire door and the difference matters more than the finish. A leaf is the door alone, hung by somebody else into a frame they supply, with ironmongery chosen separately. A doorset arrives as a complete tested assembly. The second is more expensive and much harder to get wrong.
Leaf or doorset
A doorset is manufactured and certified as one assembly, frame, leaf, seals and ironmongery, and is installed as tested. A leaf bought alone is certified only in combination with a compatible frame and hardware, and the responsibility for getting that combination right transfers to whoever specifies and installs it. On any project of size, doorsets remove the commonest source of non compliance.
When bespoke is necessary
Non standard openings, oversized leaves, unusual glazing, historic buildings and heritage profiles. Bespoke fire doors are made to a specific size within the range the manufacturer's test evidence covers, which is the critical constraint: a manufacturer can make a door any size and can only certify it within the sizes and configurations their evidence supports. Ask what evidence covers your dimensions before ordering.
Veneers and finishes
Oak, beech and other veneers are available on certified doors, and the facing is part of what was tested, so a veneer applied after the fact is an alteration. The same applies to paint systems and to laminates. If the appearance matters, specify the finish from the manufacturer's certified range rather than planning to finish the door on site.
What to check before ordering
The rating required, including whether the S suffix is needed. The size, against the manufacturer's certified range. The hardware, from their permitted list. Whether it is supplied pre hung or as a leaf. What documentation comes with it. And who will issue the installation certificate. The last one is the question most often left until the doors are already on site.
Questions people ask about made to measure fire doors
What is a fire doorset?
A complete assembly of frame, leaf, seals and ironmongery manufactured and certified together and installed as tested, rather than a leaf combined with parts chosen separately on site.
Can fire doors be made to measure?
Yes, within the sizes and configurations the manufacturer's test evidence covers. Ask which evidence supports your dimensions rather than assuming any size can be certified.
Can I veneer or paint a fire door myself?
The facing and finish are part of what was tested. Applying a veneer afterwards is an alteration; specify the finish from the certified range instead.