Neil ashdown

Make some intrusive surveys of a sample percentage of the 40 doors. If the cores are the same as fire doors, it may be possible to retain them and upgrade as necessary. "NFR" on a sticker on top of the door doesn't mean the core is unsuitable, it may be the same core as the fire doors.

https://www.lorientuk.com/products/architectural-seals

Generally, the maximum threshold gap for a fire resisting door is 10mm. For a door that is required to restrict the spread of cold smoke its 3mm. 3mm is often difficult to acheive due to imperfect floor conditions, so a 10mm gap is acceptable so long as its sealed with a flexible seal. Ref. BS 8214: 2016 Timber-based Fire Door Assemblies Code of Practice. UK Gov fire door safety guidance reconises this difficulty. https://assets.publishing.service.gov.uk/media/677fbe166f01ae28ab5c0554/A+guide+to+making+your+small+block+of+flats+safe+from+fire+2024.pdf Page 18

As Mike says, the managaing agent may have had some sort of survey or inspection including the flat entrance doors. So they should be able to provide details about why the doors are non-compliant and why they should be replaced. If they have defects, why can't these be remediated instead of replaced?

Bryony at https://www.ironout.co.uk/ can help

Samual Heath at https://concealeddoorclosers.com/powermatic-r100-concealed-door-closer/ New Star at https://www.new-star.co.uk/products/agb-eclipse-self-concealed-hinge-with-door-closer?_pos=1&_psq=self-closer&_ss=e&_v=1.0 Contact them and the door manufacturer to check suitability for your type of door, fire rating and end use.

Fire resistance performance test evidence does exist for some night latches. But compliance also depends of the core-type for the timber-based fire door in question. An experienced fire door inspector should be able to assist you. Failing that, an experienced fire risk assessor may be able to help.

If that's the only reason why the latest inspection has found the door to be unsuitable, the inspector would need to back up their finding with the relevant documentation.

If the installer says the door is non-compliant due to the thickness being 42mm or 43mm (rather than 44mm) and requires replacement, they should back that up with the relevant documentation (guidance/certification/product data sheet etc). If they can't, then what basis do they have for making that recommendation?

So, has the Installer said why the door needs to be replaced? At residential blocks below 11m in height, there's no statutory requirement to inspect fire doors to a particular schedule but there is (under Article 17 of the Regulatory Reform Fire Safety Order 2005) a legal obligation, as you would expect, to ensure fire doors "are subject to a suitable system of maintenance and are maintained in an efficient state, in efficient working order and in good repair". See https://www.legislation.gov.uk/uksi/2005/1541/article/17

End to end butt jointing of intumescent seals is acceptable if done tightly and well fitted. But don't mix different types. This website is worth visiting https://www.ifsa.org.uk/

The thickness of the door depends on the relevant certification / evidence of fire performance for the door. Also see Also see https://www.howdens.com/joinery/doors/howdens-spey-35mm-plywood-flush-fd30-fire-door-obj-sku-family-25409973 Refer to the relevant UK Gov fire safety guidance for the type of resirential block inn question eg: https://www.gov.uk/government/publications/fire-safety-in-purpose-built-blocks-of-flats https://www.gov.uk/government/publications/making-your-small-block-of-flats-safe-from-fire

You could consult https://wilkinsoncc.co.uk/ for certainty about your responsibilites.

You could try https://www.ironout.co.uk/