I need to upgrade some of the internal doors of my flat to FD30 doors. However, it looks like it will be difficult to remove the original frames due to how they are integrated into the wall. Are there any provisions or measures that can be taken that will allow us to use the original frames and just replace the doors?

Note, the original doors are not fire doors and the partitions that the doors are set into are only 80mm wide (though I believe that the partitions are plastered brick rather than timber stud).

Many thanks

Charlie

The stock answer must be, for the fire doors to meet the full standard you need to install a fire door set which is the door and frame. As you cannot remove the frame then the practical approach is to fit a new fire door with intumescent strips, which should achieve the required fire resistance, but it cannot be guaranteed. The frame in a fire door set is not special in any way, it is, just when it was tested that specification met the required standard. Why are you changing the doors if it is because of building regulations you should speak to the building control officer because it is him/she you have to convince.

If the door is 35mm thick can you put a wooden surround to make it 44mm thick?

You must check that the door leaf is suitable before attempting any upgrading works. Contact your local certificated fire door inspector for advice at www.fdis.co.uk/inspector