In article ,
John Rumm wrote:
The difference between a standard door frame, and a fire door
one, is the thickness of the doorstops. These need to be at
least 25mm thick on the fire door.

The OP should check with his BCO but IIRC you don't need 25mm
stops if the door has an intumescent strip - which you can get
from Wickes or Screwfix.

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