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