Fire Resisting Self Closing Doors

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Background


This Note for Inspecting Officers provides guidance on the standards that are considered appropriate
in respect to Fire Resisting Self
-
Closing Doors.


The Note aims to set general principles and to provide the reader with information as to which
approved
document or technical standard is considered by this Authority to be appropriate.



Further information on the testing and assessment of fire resisting metal door sets (e.g. doors with
swinging leaves) can be found in FS
-
NFG028 “Fire Resisting Metal
Doors”.




Definition of Fire Door


The expression "fire door", "fire door assembly" and "fire door set" are synonymous for the purposes
of this Note for Guidance and have the following definition: "A door or shutter provided for the passage
of persons, ai
r or things which, together with its frame and furniture as installed in a building, is
intended when closed, to resist the passage of fire and/or gaseous products of combustion and is
capable of meeting performance criteria to these ends".




Functions of

Fire Doors


Fire doors have at least one of two functions to perform and, in certain situations both i.e.



1.

To protect escape routes from the effects of fire so that occupants can safely reach a final exit;
and


2.

To protect the contents and/or structure of

a building by limiting the spread of fire.



Consequently any particular fire door may have to perform one or both of these functions for the
purposes of smoke control, protecting means of escape, compartmentation or the segregation of
special risk areas.



Performance of Fire Doors




Fire Doors for Smoke Control



Fire doors provided for smoke control purposes should be capable of withstanding smoke at
medium temperatures


Smoke control fire doors are provided for life safety purposes and play an important

role in the
vicinity of the fire in its early stages and in protecting escape routes more remote from a fully
developed fire.


Although smoke control doors are not required to meet any specific period of fire resistance,
they should be of substantial cons
truction.


Flexible edge seals should be provided for the early control of smoke movement.

Tests have shown that door stops (rebates) that have been increased to 25mm do not improve
the smoke stopping performance of doors because a fire door will bow towar
ds the fire
-
exposed side.




Fire Protection

Procedure & Guidance

Fire Resisting Self Closing Doors



Ref

FS
-

NFG
00
3

Issue/Revision Date

01/10/2010

Review Date

01/11/2013

Version

5.0


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Fire Doors to Protect Means of Escape


Fire Doors provided to protect means of escape should be capable of achieving a minimum fire
resistance for integrity of 30 minutes, when tested in accordance with an appropriate British,
European or International standard.


The doors are required to keep escape routes sufficiently free from smoke long enough to
allow occupants to reach a place of safety and to maintain integrity against the effects of fire
long enough to fulfil that object
ive. To achieve this they may need smoke seals.


NB: When other methods of smoke control are provided in buildings, e.g. pressurisation of
escape routes, the ability of fire doors to withstand smoke may not be applicable.




Fire Doors for Compartmentation
and the Segregation of Special Risks


Fire Doors provided for fire compartmentation and the segregation of special risk areas must
be capable of achieving the period of fire resistance appropriate to the structure which is not
less than 30 minutes and may
be as much as 6 hours. To achieve this level of fire resistance, it
may be necessary to provide two fire doors in series. The sum total of the fire resistance would
be designed to meet the required standard.


If such doors are also required to protect an e
scape route they will need also to have the
smoke control capabilities described above. In some circumstances e.g. the protection of
property, it may be necessary for them to be capable of withstanding high temperature smoke.


Increasing the Fire Resistanc
e of Existing Timber Doors


Increasing the fire resistance of existing doors is not normally acceptable and usually it will be more
cost effective to install a new door. However, in certain instances it may be necessary to retain an
existing door e.g. in a

listed building and, where the reasons are considered valid by an enforcing
authority it may be appropriate to modify the doors to provide an improved standard of fire resistance.



Guidance on how to improve the fire resistance of existing timber doors
can be found in:
-





Building Research Establishment Information Paper 8/82 "Increasing the fire resistance of
existing timber doors" and the Timber Research and Development Association's Wood
Information Sheet, Section 1, Sheet 32, "Fire Resisting Door se
ts by Upgrading".




Fire Safety
-

Public Advice Note FS
-
PAN0025 "Doors
-

Upgrading the Fire Resistance of
Existing Doors".



NB: An existing timber door normally can only have its fire resistance improved to a maximum of
30 minutes


Designation of Fire Door
s


Fire doors should be designated by the initials FD followed by the performance in minutes that the
door should achieve when tested in accordance with British Standard BS476: part 22 for integrity of
not less than 30 minutes (i.e. 30 minutes fire resista
nce).

Where the door should also resist the passage of smoke at ambient temperatures the suffix "S" should
be added to the designation.


Two illus
trations of this are as follows;


1.

The entrance door to a flat in a block of flats would be required to protect

the means of escape,
so that the correct designation would be FD 30s.


2.

A fire door is a 60 minute compartment wall where there are no means of escape
considerations would be designated FD 60.


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Marking Of Fire Doors



Table 1

Core
Colour

Background
colour

Integrity

Mins

Colour Code
Interpretation

All fire doors should be
permanently marked with their
designation (as above). A
convenient and recommended
method is by use of a colour
-
coded plug, inserted in the edge
of the hanging stile,

and
conforming to the table given on
the right.









Red

White

20

Intumescent seals
require to be fitted at
the time of original
installation

Yellow

30

Pink

45

Blue

60

Brown

90

Black

120

Green

White

20

No additional
intumescent seals
need to be fitted at
the time of installation

Yellow

30

Pink

45

Blue

60

Brown

90

Black

120

Blue

White

20

With no intumescent
seals fitted.




White

30

With intumescent
seals fitted in either
door edge or frame




Intumescent and Smoke Seals


For door assemblies designed to achieve 20 min or 30 min integrity, test experience shows that a
10mm wide strip of intumescent material which has satisfied the
test described in BS476: Part 23 for
the relevant period, fitted centrally into the leaf or frame rebate of a conventional sized, latched, single
leaf, single swing assembly will normally be adequate. The seal or strip may be interrupted at
ironmongery pos
itions.


For similar doors designed to provide periods of 60 minutes fire resistance or greater, the intumescent
seal specification will be at least twice that required for 30 min applications and with at least part of the
seal by
-
passing all ironmongery f
ixings.



For double leaf assemblies the quantity of intumescent seal will be that established by test and will be
dependent upon the behaviour of the door leaves.


Where separate smoke and intumescent seals are to be fitted, they should be placed with one

in the
door leaf and one in the frame.



Compression type smoke seals should be used on latched doors only (Blade and brush types do not
rely on latches).


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Frame to wall junction


The junction between a door frame and wall should be dealt with in
accordance with tables 2 and 3.



Fit of door leaf


Leaf to frame gaps should not exceed those as tested to BS 476: Part 22. Gaps exceeding 4mm are
not likely to be acceptable even when intumescent material is present. Smoke seals should make
continuous co
ntact. Gaps should allow for some settlement and shrinkage.



Threshold sealing


Intumescent sealing is not normally necessary and gaps of up to 8mm can normally be tolerated. If the
gap exceeds 3mm and total smoke control is required, a seal must be provi
ded.



Glazing apertures


Apertures for glazing or any other purpose should be provided by the manufacturer. Evidence of
manufacturer's approval would normally be required for post forming of apertures.
(See Letter
-
plates
below).

Glass and glazing beads sh
ould be in accordance with

the manufacturer's specifications.
Timber beads are likely to be suitable only if of substantial dimensions and in conjunction with
intumescent bedding mastics. See also FS
-
NFG014 “Fire Resisting Glass".



Maintenance


Fire and
Smoke Seals should be examined at six monthly intervals and replaced if necessary.

Door gaps should be examined at the same time and should receive attention if they have increased
to more than 5mm or become so tight as to over compress the smoke seals.



Replacement of glazing should be in accordance with manufacturer's recommendations.

Hardware should be appropriately lubricated.



Replacement of hardware should be with identical components, or ones approved by the manufacturer
and any gaps resulting
should be filled with suitable intumescent material.

Self
-
closing devices and latches should be checked at six monthly intervals to ensure they are working
fully and effectively
.



Self Closing Devices


A fire door (except to a cupboard or service duct)
should normally be fitted with a self closing device
(other than rising butt hinges) that:



1.

Should be of a type that cannot readily be disconnected or immobilised and does not embody
a stand
-
open action;


2.

Should override any latches fitted to the door(s);

or in the absence of a suitable latch or other
positive device for holding the door shut in its frame, should be of a type that has been shown
by test to be capable of holding the door closed in the frame for a sufficient period of time for
the closing ro
le to be taken over by a thermally activated sealing device (such as an
intumescent seal), or throughout the full period of exposure if such seals are not incorporated.




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Letter
-
plates (Letterboxes)


The provision of letter
-
plates in fire resisting doors
should be avoided where possible and approval
should be obtained from any enforcing authority before they are installed. Letter
-
plates are not
acceptable in any door required to give a fire resistance greater than 30 minutes. An acceptable
alternative to t
he provision of letter
-
plates is separate mail boxes that can be protected more easily
from the effects of fire.


The following criteria should apply before the Fire Authority will consider giving approval for the
provision of a letter
-
plate in a fire
-
resi
sting door:
-


1.

The door must be of suitable construction and the aperture cut in the door must be in an area
of solid timber.


2.

The size of the aperture cut in the door must not exceed the size of that in the letter
-
plate.


3.

The letter
-
plate should be sited
900mm up from the floor as this is where the neutral pressure
axis is expected to be in a fire situation.


4.

The letter
-
plate must be constructed from metal and have a positive spring closer fitted to it.


5.

A stainless steel inner flap with a positive spring
closer must be provided. It should have a
generous overlap which must not be less than 10mm and it must be independently screwed to
the door and not be reliant on the bolt fixings from the back of the letter
-
plate to hold it in
position.


6.

A combined smoke
and intumescent seal must be provided around the aperture cut in the door
and the inner flap must close onto this seal.




Notices




Fire doors should be marked "FIRE DOOR
-

KEEP SHUT" on each face unless it is a door to a store
room, service duct etc, in

which case it should be marked "FIRE DOOR KEEP LOCKED" on the outer
face. The size, shape and colouring of the notice should comply with BS 5499: Part 1: 1990, Appendix
B.3 "Mandatory Signs".





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Table 2


RECOMMENDATIONS FOR THE JOINT BETWEEN TIMBER DOOR
FRAMES AND WALLS TO
PROVIDE 30 MIN FIRE RESISTANCE

Wall Construction


Maximum Frame to
Wall Gap Width


Architrave Condition


Additional Protection


Non
-
load bearing walls
unlikely to exhibit
significant distortion
during fire exposure
e.g. timber stud wa
lls
and masonry walls
without fair face >

Up to 10mm >

Intimately fitted soft of
hard wood architraves
at least 15mm thick
with a 15 mm overlap
onto the wall and door
frame >

Nil

Imperfectly fitting
architraves >

2mm x 10 mm of
intumescent material

as a pre
-
formed strip or
seal

or

mineral or glass wool
packed to a depth of at
least 10mm

or

A bed of intumescent
mastic

More than 10mm >




All architrave
conditions >

Load bearing walls
likely to exhibit
distortion during fie
exposure e.g. steel
stud walls >

All gap sizes >

Fit of architrave cannot
be guaranteed due to
likely distortion of the
wall >

Load bearing or non
-
load bearing walls. Fair
faced masonry walls
>

More than 10mm >

All architrave
conditions >

Up to 10mm >

Immediately fitted
19mm hardwood
quadrant bead >

Nil

NOTE:

There is a risk that wall finishes with a surface spread of flame rating of Class 3, as defined in
BS476:Part 7, may contribute to ignition and flaming of the architrave on the unexposed face due to
leakage of hot gases. For smoke control door sets frame
to wall gaps should always be packed with
mineral or glass wool or sealed with a bead of intumescent paste or mastic.




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Table 3


RECOMMENDATIONS FOR THE JOINT BETWEEN TIMBER DOOR FRAMES AND WALLS TO
PROVIDE 60 MIN FIRE RESISTANCE

Wall construction

Maximu
m Frame to
Wall Gap Width

Architrave Condition

Additional Protection

Non
-
load bearing walls
unlikely to exhibit
significant distortion
during fire exposure
e.g. timber stud walls
and masonry walls
without fair face >

Up to 10mm >

Intimately fitted soft or

hard wood architraves
at least 15mm thick with
a 15mm overlap onto
the wall and door frame
>

2mm x 10mm of
intumescent material as
a pre
-
formed stop or
seal

or

mineral or glass wool
packed to a depth of at
least 10mm

or

A bead of intumescent
mastic

Imperfectly fitting
architraves

>

2mm x 20mm of
intumescent material as
a pre
-
formed strip or
seal

or

mineral or glass wool
packed to a depth of at
least 10mm

or

A bead of intumescent
mastic

More than 10mm >

All architrave conditions
>

Load bearing
walls
likely to exhibit during
fire exposure e.g. steel
stud walls >

All Gap sizes >

Fit of architrave cannot
be guaranteed due to
likely distortion of the
wall >

Load bearing or non
-
load bearing walls. Fair
faced masonry walls >

All Gap sizes >

All
architrave
conditions

>


NOTE
: There is a risk that wall finishes with a surface spread of flame rating of Class 3, as defined in
BS476:Part 7, may contribute to ignition and flaming of the architrave on the unexposed face due to
leakage of hot gases. Fo
r smoke control door sets frame to wall gaps should always be packed with
mineral or glass wool or sealed with a bead of intumescent paste or mastic.