Just after people’s thoughts, advice etc,

we’ve been fitting fd60 firedoors and on the whole attaining a 3mm gap between floor and door, but as nothing is plumb and level in places the gap is bigger and with floors rising as door opens in its closed state the gap can sometimes be over 5mm, drop seals are not an option, is this an allowable gap under the circumstances ??

thanks in advance 

Obviously floor conditions can be outside the control of the fire door installer.  Where the 3mm gap cannot be achieved options are fitting a threshold plate to the floor or fitting a drop-down seal to the door leaf bottom edge.

Where fitting of those is not possible then the person or organization that has control of the building and responsibility for fire safety should make a risk based decision about whether the excessive gap is acceptable.  If deemed not acceptable then remedial action to the floor condition will be necessary.

The following is from ASDMA on BS 8214:

So long as there is no pressurisation present, the only statutory requirement is for head and jambs to resist the passage of cold smoke

That's your interpretation of course, but does not reflect what is being enforced out there, nor makes some of the massive gaps that shoddy contractors are putting in acceptable.

I would want and expect any door that I paid for the installation of to comply with the regulations that were in force at the time of installation, but why should I go over and above what the regulations are telling me to do.

If there is no pressurisation present, then the only statutory requirement is for the head and jambs to resist passage of cold smoke, I would be happy with up to a 10 mm gap at the threshold provided that the door certification allows for it.

That is mine and also Exova Warringtomfire understanding of the current regs.