Fire door frame gap advice required

[William Austin]

I'm looking for some advice regarding the fire doors in my house, and help to validate some remedial works to address the gaps between the fire door frame and the wall it is installed into.

 

New build detached house built in 2017, fire strategy being a protected stairway, last year we discovered that the gaps between the fire door frame have not been sealed, when the architraves were removed

we can see clear through the gaps into the room behind.

 

There are four fire doors on the ground floor within the protected stairway, two of these are doors to storage areas, one under the staircase and the other to a small storage area which includes the fuse box.

 

On the first floor there are five fire doors, four leading to bedrooms and one to the area where the boiler is located.

 

With the exception of the kitchen door, which is fitted into a load-bearing block wall, the supporting construction for the remaining fire doors is a timber stud, the timber studs measure between 55mm and 60mm,

these are lined with a single layer of 12.5 standard plasterboard on each side, and 3mm of plaster skim.

 

The packing for each door frame to wall are plastic hollow packers, the type where the colour denotes its thickness in millimeters.

 

The plasterboards are recessed back from the finished edge of the timber studs on many of the walls, this appears due to the plasterboard having been badly cut at their edges, the recess measuring between 5 and 10mm from the finished edge of the timber stud.

 

The work to remedy the missing gap seals is to install rock fiber into the gaps and cap it both sides with 10mm to 15mm of fire resistant acrylic sealant, this would require the plastic packers to be rotated downwards, the packers are 43mm wide.

 

The fire rating for our doors is 30 minutes.

 

My questions are:

 

1:  BS 8214:2016 only provides directions for gaps with a maximum width of 20mm, many of the gaps between our fire door frame and wall are over 20mm, some being 35mm, is 20mm the maximum gap width permitted ?

 

2:  BS 8214:2016 states in relation to door frame packing that suitable solid packing should be used, ours are hollow plastic, I assume that heat would melt this and given that they are hollow would allow its shape to reduce in size, possibly

allowing the door frame to move, are these types of packers valid for use with fire doors?

 

3: Two gaps which have a gap width of over 30mm are to be lined with a sheet of plasterboard to reduce the gap width, the information related to the fire door only states that the supporting construction can be lined with soft or hard wood, would

a lining of plasterboard be valid?

 

Many thanks

[Neil Ashdown MAFDI]

Q1:  BS 8214:2016 only provides directions for gaps with a maximum width of 20mm, many of the gaps between our fire door frame and wall are over 20mm, some being 35mm, is 20mm the maximum gap width permitted ?

A)  There are some foam products that have been successfully fire tested for use with fire doors at gaps over 20mm.

 

Q2:  BS 8214:2016 states in relation to door frame packing that suitable solid packing should be used, ours are hollow plastic, I assume that heat would melt this and given that they are hollow would allow its shape to reduce in size, possibly

allowing the door frame to move, are these types of packers valid for use with fire doors?

A)  The plastic packers should be cut back by at least 10mm and sealed over with intumescent mastic, so that they are encapsulated by the mineral fibre and intumescent mastic system.

 

3: Two gaps which have a gap width of over 30mm are to be lined with a sheet of plasterboard to reduce the gap width, the information related to the fire door only states that the supporting construction can be lined with soft or hard wood, would

a lining of plasterboard be valid?

A) Not sure that plasterboard has been fire performance tested in this scenario but have been told that building control would accept this.  Personally, I would remove the door frame and screw timber to its back edge, continuous in width and length, to increase the door frame thickness accordingly. 

 

Have you informed NHBC, local building control and the builder about these non-compliance issues?

Edited March 8, 2023 by Neil Ashdown MAFDI
To add to an existing comment.

[William Austin]

Thank you for your reply.

I am aware of some fire rated sealants that can be used for gaps wider than 20mm, although these seem to require that you use their proprietary packers.

The sealant used to cap the rock fibre for our fire door gaps does have test evidence for its use in linear joints and gap seals over 20mm, however the ETA for the sealant testing data doesn't show its use in relation to fire doors, it does show its use in sealing gaps between Timber/Timber, Plasterboard/Plasterboard and Timber/Plasterboard, however the gap width directly relates to the depth of the sealant, i.e to seal a gap of upto 30mm would require the sealant to be applied to a depth of 17.5mm, also the sealant test data all relates to E60, E120, E240, there appears to be no testing for E30.

Also the sealant ETA tests require a wall depths of 100mm and above, ours are 85mm wide and a couple are around 80mm, and this includes the 3mm of skim each side.

A) Not sure that plasterboard has been fire performance tested in this scenario but have been told that building control would accept this.  Personally, I would remove the door frame and screw timber to its back edge, continuous in width and length, to increase the door frame thickness accordingly. 

I did report this to the builder but they refused to fix it, I then opened a claim with our home warranty provided, they also performed Building Control for the house.

The technical drawing for the house claim that the stud walls are a proprietary system, this system has an E30 rating under BS 476: Part 22 but not under BS EN 1364-1, as BS EN 1364-1 requires 15mm standard plasterboards, the home warranty provider provided me with the specs for the proprietary system, only when the fire door architraves were removed did we discover that the stud walls were not the claimed proprietary system, the timber studs are narrower and the fixing requirement listed in the proprietary system specs related to fire/smoke/sound performance have not been followed, at this stage we are unsure what the fire rating of the stud walls are.

Below is a photo of the door frame and how the plasterboard has been cut back from the timber stud

 

 

 

 

 

 

[Neil Ashdown MAFDI]

Yes, this is typical of the different types of non-compliance issues that Fire Door Inspectors see on a daily basis.  Installation of timber-based fire doors should be in accordance with BS 8214: 2016 Timber-based Fire Door Assemblies: Code of Practice and the door manufacturers product data sheet / installation instructions.