Neil ashdown

A threshold gap of 25mm is excessive for both fire resistance performance and smoke spread performance. Can the floor condition be remediated and/or can a threshold plate be fitted to the floor directly under the door in its closed position?

A gap of 10mm between the edges of the door leaf and door frame is excessive, this applies at the top edge and at the vertical edges. The Standard 'BS 8214:2016 Timber based fire door assemblies - Code of practice' states that "a typical gap to achieve good fire performance is between 2mm and 4mm".

Lipping must be of a suitable hardwood and fixed with an adhesive appropriate to the door fire rating and type of timber core/rail. Lipping should be one piece, rather than two pieces used double thickness. For FD30 minimum 6mm thick and maximum 19mm thick with maximum 2mm profiling at the corners. For FD60 minimum 6mm thick and maximum 15mm thick with maximum 2mm profiling at the corners.

Does the door have attributes that are present on a fire resisting doors? Eg: Is it solid core, are there any markings on the top edge of the door that indicate the door is fire resisting? Are you able to satisfy yourself that the door is fire resisting?

When the doors are fire resistance tested the intumescent seals would be continuous in one piece. Therefore they should be installed the same way. Gaps should be between 2mm and 4mm generally, but abide by the particular requirements for the installation instructions for that door. The smoke seal should close the gap but the tip of the smoke seal brush/blade should only lightly contact the surface of the door leaf edge or door frame reveal in the closed position. Intumescent strips, if installed correctly, should not become worn. If they become damaged, replace them with the correct strip. Smoke seals may become worn so replace them with the correct seals.

The chain, as described with the image above, could be fitted at approx. 1500mm above floor level.

The issue here is not to do with the compliance of the door. The floor should be 100mm lower than the door threshold. Imagine the garage floor was flooded with petrol..............

So the issue appears to be certification of the work. Normal practice would be to completely and tightly pack the gap with mineral fibre and then seal to a 10mm min depth to both sides with the Fire Acoustic Sealant. Refer to BS 8214:2016 for minimum requirements. If the architect will not allow the use of Blue 60 and the dedicated packers in place of the sealant/fibre combination, then you have two options: 1) Ask the Blue 60 manufacturers what evidence of fire performance is available for use of Blue 60 in full accordance with the fire test evidence but with an additional depth of Fire Acoustic Sealant to both sides. Note, we are saying 'in full accordance' so that the sealant is an extra-over to the fire stopping requirements. Clearly door frame material type, depth of foam and gap size is a major factor here. 2) Use mineral fibre and fire acoustic sealant in accordance with BS 8214:2016.

When inspecting the gaps between the edges of the fire door leaf and the door frame: 1) Check the gap is between 2mm minimum and 4mm maximum, generally (consult the door leaf data sheet for certainty about the requirements). 2) Ensure that the smoke seal brush or blade (where required) is in light contact with the surface that it sweeps or compresses against, in the door fully-closed position. 3) Ensure that the door leaf does no stand proud of the door frame (and not proud of the other leaf of double doors). The door frame rebate does not provide significant protection against the spread of cold smoke, therefore smoke seals should be fitted where smoke protection is necessary.

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:

This type of self-closing device is designed to be easier to open. Contact the manufacturer to find out which device is best suited to your needs and that of the flat entrance door as these must be self-closing fire doors with restricted spread of smoke.

Ditto

The guidance you need as follows: BS 8214: 2016 https://shop.bsigroup.com/ProductDetail/?pid=000000000030332501 IFSA https://www.ifsa.org.uk/documents Unless the brush seals are offset, there shouldn't be room for two brush seals as the gap between the edge of the door leaf and the frame should generally be 4mm max and 2mm min. Same for the gap at the meeting edges of double leaf doors. Be careful to ensure that the brush seals do not prevent the doors from self-closing completely. In the door closed position, the brush (or blade) should only lightly contact the surface that it sweeps.

If the seal is making a noise when the door opens, it is most likely from the brush or fin that provides restricted smoke spread protection. This type of seal needs to make light contact with the opposing surface in the door closed position so the noise is most likely due to friction. If the noise is a problem you could change the seals (all of them) for fire only seals (below) used in conjunction with the type of smoke/acoustic seal (bottom).

Refer to BS 8214:2016 Timber-based fire door assemblies - Code of practice for details about how to seal the gap.

Is it a new door? Do you have the name of the manufacturer (is there a label on the top edge of the door)?

Possibly repairable depending on extent of damage and of course, so long as the core of the door is not damaged.

Follow guidance BS 8214:2016 Timber-based fire door assemblies - Code of practice https://shop.bsigroup.com/ProductDetail/?pid=000000000030332501 with regard to specification of door assembly components.

Best to check with local authority building control on fire door requirements then. Protected escape route from upper floors, Approved document B (dwellings) Annex C Fire Doors.

Does the work you are doing fall within the scope of Building Regulations?

Yes, timber packers should be used at all fixing points so that you can get a secure fixing. They can be full width of the door frame. Ensure the mineral wool is tightly packed to fill all gaps and leave no voids then cap the wool on both sides with a 10mm depth of intumescent mastic.

Yes, Oak is a good timber for a fire door threshold.

The regulations in terms of access and use of buildings is https://www.planningportal.co.uk/info/200135/approved_documents/80/part_m_-_access_to_and_use_of_buildings I would advise you to check with local authority building control as to whether your proposal is in scope of Part M requirements for dwelling houses. There are limits to how narrow a fire door leaf can be in terms of its fire resistance performance but as you haven't said how narrow the door would be, I cannot comment further.

Assuming the fire doors are wooden ones. Strip and paint them as you would any wooden door. Do not paint over smoke seals and avoid adding metallic facings.