I am working for a client transitioning a home to a non-licensable HMO. They want to move back in after a few years. They have a good quality, solid 1935mm high opening/frame/lining.

All of the doors I'm looking at are 1981mm with too little lipping to bring the door to height. The client hates all of the doors available from made-to-measure suppliers.

I understand that it's possible to re-size FD30 doors using hardwood lipping glued in (and not from the top). What's the best method for this to remain HMO-compliant. Please note that this is a non-licenseable HMO.

1) Cut door to size and glue in hardwood lipping of 6mm + 5mm (for intumescent rebate) thickness

2) Router out 11mm groove in base of the door to try to keep veneer intact and glue in a cut-to-size hardwood lipping

Are all FD30 doors solid core?

Is this best done with a FD30 blank or can it be done with a finished door?

Better to change the door frames to suit the new doors.

If that's not possible either order custom made fire doors from a competent supplier or if you have the necessary knowledge, skills and experience you could purchase fire door blanks and fabricate the doors yourself in accordance with it's relevant technical manual.