Hi, 

I've recently installed new carpets to my bedrooms and need to trim the bottom of the fire door by 1-2mm.

I've checked the certification label and found relevant information on the manufacturer's website that 10mm gap is allowed and I would meet this requirement even if I remove 2mm from the doors. 

All is good but the trouble is I found the certification label on the bottom of the door leaf, not the top!

I now wonder if the developer of the flats installed the door upside down. Unfortunately if the door is to be trimmed the label would definitely have to be removed. While I understand the door will no longer be guaranteed by the certification, would it still be a safe fire door if it meets the gap requirements? Or has it never been safe due to the fact that it wasn't installed the right side up?

Any advice greatly appreciated. Thanks.

I see no problems except you will need to destroy the label however the door will maintain its fire resisting standards, you should try to remove it and fix it to the top if possible.

Whether or not a timber based fire door would still provide the required level of fire protection when installed upside-down depends on its core construction. As you have the label you can contact the technical help desk at the door manufacturer to find out.

Don't forget the threshold gap should be 3mm not 10mm where cold smoke protection is required. Or you can fit a threshold seal.

Thank you very much for your replies, Tom and Neil. The manufacturer has confirmed that the door is symmetrical top and bottom so being upsidr-down is not an issue. I've also managed to remove the label without damaging it (much) so will fix it at the top.

Thanks!

As long as it is readable it should be fine but you may get some suspicious glances from inspectors but you will be able to explain yourself.