Fire doors and intumesant strips

Just finishing a loft conversion where the new regs mean I have to fit fire doors to all habitable rooms in the house.

Never done one before but from looking about it would seem sensible to fit the stripping to the door itself before fitting rather than trying to get it into the existing frame?

Does that sounds the most sensible way?

Any other pointers? My doors are give or take a couple of MM standard sizes so can you buy the doors with strips ready fitted?

Thanks,

Generally a fire door will have a label identifying it as a fire door so that you can prove it to the building inspector, if you're buying a fire door make sure it has one; http://images.google.co.uk/imgres?i...m=10&um=1&hl=en&cr=countryUK%7CcountryGB&sa=N