Detailed Construction of fire doors
FD30 (30 minutes) fire doors are usually 45mm thick, as opposed to the standard door thickness of 35 mm, there is absolutely no point if fitting a fire rated frame if you then fit a standard non fire door.
FD60 (60 minute) fire doors most commonly used in commercial settings are normally 54mm thick. Specially constructed fire doors can have a rating of 4 hours or more, this is very much dependent on fitting ALL of the correct materials.
Most fire doors have a solid core construction which can include: particleboard, chipboard, flaxboard and solid timber.
The assembly of a fire door can vary greatly, some have: a timber framing around the core with a laminated veneer; others have a lipping (5-20mm thick) around the core with a veneer on top; and in some cases a plywood, veneer or MDF facing is glued on to the core without framing or lippings.
There is no preferred or regulated construction method and no need for one as long as the desired fire rating is acheived.