Fire doors floor thresh hold gap 8mm?

[Redone]

Regarding the gap at the base of the door, for some reason I think it's 8mm, is this about right?

New hard wood thresholds going in under the bedroom doors and the gap likely to increase by 10 - 15mm.

But if 8mm is the target...

[Andy Gwatkin]

You  do need to get out more, no offence but if this is your only worry in your premise then i suggest your not doing bad at all, especially with the RRO and all its baggage, at the end of the day what are you looking at People or Property protection. If the smoke is at the bottom of the door and your still in the building then i think you should re address your FRA !!!

[kurnal]

Ah but dont limbo dancers rule in South Wales?

New doorsets are worth working on to get them right. Yes the ideal target would be 3mm- but that is impossible to maintain. 8mm is the maximum that a half decent joiner would aim for but if you are looking an old building then in reality 10-15mm would be pretty good.
Suppose to some extent it depends where the door is- if its into a single staircase in a multi storey HMO one would be a bit more careful than in an two storey office.
I understand that the risk of an excessive gap at the base of the door is to allow a good supply of fresh air into  the fire and thus increase the intensity of the fire, placing the head of the door at greater risk.
Dont forget that all these tests and standards are theoretical and only a comparative measure of one doorsets performance against another. The test furnace may bear little resemblance to the real  fire that may occur in a building.

[Redone]

Cheers Big G and Kurnel...

Asked the question by a property services person for a care home being refurbished.  My reply covered all the points you both mentioned including why am I doing this.

FRA is top hole, L1 AFD, first class response time, (usual doubts about night staff levels) just the chippy needs guidance, good of him to ask, makes a change.

Mitch