the event of fire the destructive forces acting on your doors obviously
include high temperatures and the flames themselves, but gases are
also heated. These gases expand, and create higher pressures than
normal. The natural tendency is for the gases to flow from these
higher pressure spaces into lower pressure spaces, thus helping
the spread of the fire. Under normal daily conditions however a
door still needs to retain its looks and functionality. The main
things to consider therefore when trying to improve the fire resistance
of e.g. timber doors are:
In a fire a door is likely to fail first by distortion rather
than burning through so both eventualities need to be considered
The door appearance and any ornate features may be important to
retain and it may be difficult and inconvenient to have to take
a door off of its hinges in order to upgrade its fire resisting
The pressurised gases caused by the temperature of fire will try
to find their way through gaps in the door / door set. Smoke (hot
and cold) will also pass through gaps. This needs to be considered
in the overall upgrading plan.
The complete fire resistance of any door assembly is actually
down to a combination of preventative planning and measures taken
on the frame, the door ironmongery and the actual door itself.
Seals such as Fireplug Intumescent Strips (which have a protective
PVC sleeve) can be applied for example to the edge of the door leaf
or on the actual face of the door frame itself. It is also worth
noting that there can also be a gap between a door frame and the
wall which can be exploited by fire although these particular gaps
are generally hidden architrave. Ideally Intumescent Fire Seals
should be (should have been) fitted to the back of the door frame
itself before it was installed. Intumescent Seals react to high
temperatures by expanding and therefore closing gaps in the door
sets and frames.
the The Door(s)
Fireplug FUS door upgrading system (for timber doors) is simple,
effective, and involves the use of 3 different coatings:
1. Fireplug CFPM – a 0.5mm thick intumescent paper.
2. Fireplug ICT – a water based acrylic intumescent coating.
3. Fireplug TSC – a sealing coat to protect against mechanical
damage and moisture.
The first part
of the process of using this system means ensuring that the door
surface is as clean as possible to aid adhesion e.g. rubbing with
sandpaper and wiping with a cloth with white spirit.
After brushing on a coat of ICT (the acrylic) the CFPM (paper) should
be cut to size and applied to the door, and then coated with another
layer of CFPM. After this a double coat of ICT can be applied. After
all of this has dried the TSC (sealing coat) can be applied –
this may require 2 coats.