Fire Resistance – General
Notes:- Several of the following by-laws require that the various parts of a building shall resist fire for
specified periods. These requirements so far as walls are concerned shall be satisfied either if the
construction is in accordance with the Third Schedule of these By-laws dealing with traditional methods
of building, or if the construction is in accordance with the Fourth Schedule of these By-laws (which
lists most of the common forms of construction). If the construction is not in accordance with either of
the aforesaid Schedules, then the fire resistance must be shown to be adequate by reference to a test on a
similar form of construction in accordance with British Standard No. 476 under by-laws 69 and 70 of
these By-laws.
Interpretation.
69. (1) Save as provided in paragraph (b) of by-law 72 and by-law 75 of these By-laws, any requirement
in these By-laws, that a structural part of a building shall have a fire resistance of a specified period
shall be construed as requiring that that part shall be capable of resisting the action of fire thereon for
that period under the conditions of the test appropriate to that part under British Standard 476 “Fire
Tests on Building Materials and Structures” and any part of a building shall be deemed to have the
requisite fire resistance if –
(a) it is constructed as to have, in accordance with the Fourth Schedule of these By-laws, a
notional period of fire resistance not less than the specified period; or
(b) a similar part made to the same specification as that part is proved to have the requisite fire
resistance under the conditions of the aforesaid test.
(2) For the purpose of this by-law, resistance to the action of fire in the case of a wall shall be taken to
mean resistance by that wall to fire on one side at a time, therefore in by-law 72 of these By-laws,
resistance to internal fire or external fire in relation to a wall shall be taken to mean resistance to fire
only on the inside or the outside of that wall as the case may be.
(3) The expression “non-combustible throughout” in relation to a wall means composed entirely, apart
from any combustible internal lining, of non-combustible material or materials.
(4) A wall required by these By-laws to be externally non-combustible shall be either a wall noncombustible
throughout or one having non-combustible external panels or covering.
Walls complying with Third Schedule of these By-laws.
70. Any wall complying (in respect of its stability) with the Third Schedule to these By-laws, shall be
deemed to satisfy all requirements relating to the non-combustibility and fire resistance of external
walls provided for in by-laws 72, 77, 78 and 80 of these By-laws and the similar requirements in respect
of the walls referred to in by-laws 73, 78 and 81 of these By-laws.
Fire Resistance – Small Houses
Definition of small house.
71. In any of these By-laws, relating to fire resistance “small house” means a one or two-storeyed
dwelling house of a capacity of less than 20,000 cu. ft. but does not include a flat.
External walls of small houses.
72. Every external wall of s small house shall –
(a) Comply with the requirements as to non-combustibility and fire resistance specified as
appropriate thereto in column (2) of the Table set out below according to the distance of
the wall from the nearest boundary of the plot as shown in column (1) of that Table; and
(b) Have a resistance to internal fire of half an hour, for the determination of which the
conditions of test referred to in paragraph (1) of by-law 69 of these By-laws shall apply
with the modification that the limit of temperature rise on the unexposed face as specified
in paragraph 11c of British Standard 476 “Fire Tests on building Materials and Structures”
shall not apply.
TABLE
(1)
Distance of wall in ft. from
nearest boundary of plot
(2)
Appropriate requirements
as to non-combustibility and
fire resistance
Not less than Less than
10 – No requirement
5 10 To be externally non-combustible
3 5 To be non-combustible throughout
– 3 To be non-combustible throughout and to have
a resistance to external fire of half-an-hour.
Walls separating small houses.
73. (1) Subject to the provisions of paragraph(2)of this by-law, in a building comprising two or more
small houses, a wall separating such houses , shall be non-combustible throughout and shall have fire
resistance of one hour.
(2) (a) Where the external walls of a building comprising more than two small houses have combustible
externals panels of covering, the walls separating successive groups of not more than two such houses
shall-
(i) have a fire resistance of two hours;
(ii) extend not less than 9 in. beyond the outer surface of the external wall; and
(iii) (unless the roof is of solid or hollow slab construction of non-combustible material) be
carried not less than 15 in. above the roof (measured at right angles to the slope).
(b) Where the external walls of a building comprising more than four small houses have combustible
frames but non-combustible external panels or covering, the walls separating successive groups of not
more than four such houses shall have a fire resistance of two hours and no part of the combustible
construction of the external walls shall extend across the ends of any of the separating walls.
(c) Where the external walls, including any external panels or covering, of a building comprising more
than eight small houses are non-combustible, the wall separating successive groups of not more than
eight such houses shall have a fire resistance of two hours.
Further provisions as to walls separating small houses.
74. (1) No combustible material shall be shall be built into or carried through or over a separating wall
to which by-law 73 of these By-laws applies, other than-
(a) The ends of wooden beams, joists or purlins which are properly protected by brickwork or
other solid and non-combustible material not less than 4 in. thick, or by a beam box of iron
or other suitable non-combustible material; or
(b) Tiling or slating battens properly embedded in mortar or other suitable material.
(2) Where any separating wall to which by-law 73 of these By-laws relates is not carried up above the
underside of the covering of the roof, the slates or other covering or slab shall, where practicable, be
properly and solidly bedded in mortar on the top of the wall.
Floors and interior walls of small houses.
75. (1) In every small house of two storeys, the upper floor shall be so constructed as to be capable of
satisfying the test for fire resistance specified in British Standard 476 “Fire Tests on Building Materials
and Structures” as to freedom from collapse for half an hour, and as to rise of temperature and freedom
from cracks or similar failures for 15 minutes.
(2) Any floor to which paragraph (1) of this by-law applies, shall be deemed to have the fire resistance
required by that paragraph if it is constructed in accordance with the relevant provisions of Table B of
the fourth Schedule to these By-laws.
(3) In every small house, all load bearing walls, other than a wall to which by-laws 72, 73, 74 and 76 of
these By-laws apply, shall have a fire resistance of half an hour for the determination of which the
conditions of test referred to in paragraph (1) of by-law 69 of these By-laws shall apply subject to the
modification, that the limit of temperature rise on the unexposed face as specified in paragraph 11c of
British Standard 476 “Fire Tests on Building Materials and Structures” shall apply.
Garages attached to dwellings.
76. (1) For the purpose of this by-law a garage means a covered space capable of accommodating a
motor car, enclosed on more than two sides or with a room above.
(2) Where a garage is built as part of a dwelling or attached thereto-
(a) the underside of the floor of the room above the garage, shall be properly ceiled with
non-combustible material having a fire resistance of not less than half an hour;
(b) the material covering the roof of the garage shall be as specified in by-law 94 of these
By-laws;
(c) all walls separating the garage from the remainder of the building, not being walls to
which by-laws, 73, 81 and 87 of these By-laws apply shall have a fire resistance of not
less than half an hour, and be of non-combustible material and contain no combustible
linings;
(d) an opening in an wall referred to in subparagraph (c) hereof shall-
(i) at its lowest point be at least 4 in. above the level of the floor of the garage.
(ii) be protected by self-closing doors, having a fire resistance of half an hour; and
(iii) be so arranged that access is in accordance with by-law 163 of these By-laws.
(3) A door for the purpose of subparagraph (d) (ii) of paragraph (2) of this by-law shall be deemed to be
self-closing if it is hung on efficient rising butts, and shall be deemed to have the requisite fire
resistance if constructed in accordance with the specification in British Standard 1459: Part 3, for doors
having a fire resistance of half an hour.
Fire Resistance of Buildings Other Than Small Houses
General rule as to external walls, other than walls of small houses.
77. The external wall of any building, other than a small house shall, unless otherwise provided for in
these By-laws, be non-combustible throughout and have a fire resistance of more than two hours.
Modification for External walls of certain one storey buildings.
78. (1) Every external wall of a domestic or public building of one storey, not being a small house,
shall, if the building has a capacity specified in column (1) of Table set out below, and the distance of
the wall from the nearest boundary of the plot corresponds with any distance specified in column (2) of
that Table opposite the appropriate specification in column (1), comply with the requirements as to noncombustibility
and fire resistance specified as appropriate thereto in column (3) of that Table.
TABLE A
(1)
Capacity of building in cu.
ft.
(2)
Distance of wall in feet
from nearest boundary of
the plot
(3)
Appropriate requirements as to noncombustibility
and fire resistance
Not less than Less than Not less
than
Less than
– 18,000 10
5
3
–
10
5
No requirement.
To be externally non combustible.
To be externally non-combustible and
to have a fire resistance of one hour.
18,000 36,000 20
10
5
–
20
10
No requirement.
To be externally non combustible.
To be externally non-combustible and
to have a fire resistance of one hour.
36,000 – 10 – To be externally non-combustible and,
unless it is an office building more than
30 ft. from the nearest boundary of the
plot, to have a fire resistance of one
hour.
(2) Every external wall of a building of the warehouse class, not intended to be used wholly or
predominantly for storage, and comprising only one storey shall comply with the requirements as to
non-combustibility and fire resistance specified as appropriate thereto in column (2) of Table B set out
below according to the distance of the wall from the nearest boundary of the plot as shown in column
(1) of that Table.
TABLE B
(1)
Distance of wall from nearest boundary of plot
(2)
Appropriate requirements as to
non-combustibility and fire
Not less than Less than resistance
20 ft. or a distance equivalent
to half the height of the
building (whichever is the
greater).
40 ft. or a distance equivalent
to the height of the building
(whichever is the greater).
To be externally non-combustible
and to have a fire resistance of one
hour.
40 ft. or a distance equivalent
to the height of the building
(whichever is the greater).
– To be externally non-combustible.
(3) Where a building, other than a small house, is completely separated into two or more parts by firedivision
walls complying with by-law 84 of these By-laws, the requirements of paragraph (2) of this bylaw
shall be deemed to be satisfied, if the external walls of each such part, have the non-combustibility
and degree of fire resistance appropriate in the case of an entire building of the same cubic capacity as
that part.
Modification for external walls of certain buildings of more than one storey.
79. Where an external wall of a domestic building of two or more storeys, other than a shop or small
house, is a panel wall supported in a structural frame of metal or reinforced concrete and is constructed
of non-combustible material and is not less than 10 ft. or a distance equivalent to half the height of the
building, whichever is the greater, from the nearest boundary or in the case of existing premises from
those premises, the frame and panel of such wall shall have a fire resistance of one hour.
Modification for external walls of large storage buildings.
80. Every external wall of a building of the warehouse class intended to be used wholly or
predominantly for storage shall, if the capacity of the building exceeds 250,000 cu. ft., or if its height
exceeds 75 ft. be non-combustible throughout and have a fire resistance of four hours:
Provided that where a building is completely separated into two or more parts by fire-division
walls complying with by-law 84 of these By-laws, by-law 84 shall apply as if each such part were a
separate building.
Separating Walls.
81. (1) This by-law shall apply to walls separating houses or other buildings, not being walls, to which
by-law 73 or by-law 86 of these By-laws apply.
(2) The wall shall be non-combustible throughout.
(3) The wall shall, if constructed for the separation of domestic buildings, other than shops, have a fire
resistance of four hours, and in any other case, it shall have a fire resistance of six hours.
(4) Where the council agrees to an opening in a wall, it shall be protected by doors or shutters having a
fire resistance of half the period required for that wall.
(5) No combustible material shall be built into or carried through or over the wall, other than-
(a) the ends of wooden beams, joists or purlins which are properly protected by brickwork or
other solid and non-combustible material not less than 4 in. thick, or by a beam box of iron
or other suitable non-combustible material; or
(b) tiling or slating battens properly embedded in mortar or other suitable material.
(6) Except as provided for in by-law 82 of these By-laws, if the roofs of the buildings separated by the
wall, are not of solid slab or are of hollow slab construction of non-combustible material-
(a) the wall shall, if either of the buildings separated by it is a public building or a building of
the warehouse class, be carried up above the underside of the covering of the roof for a
distance of at least 18 in. (measured at right angles to the slope);
(b) the wall shall, if the buildings are domestic buildings and either of them comprises more
than five storeys, be carried up above the underside of the covering of the roof for a
distance of at least 12 in. (measured at right angles to the slope).
(7) In any case other than one to which paragraph (6) of this by-law applies, if the wall is not carried up
above the underside of the covering of the roof, the slates or other covering or slab shall be properly and
solidly bedded in mortar on the top of the wall.
Buildings erected on single plot for different tenancies.
82. If a building is capable of being let in different tenancies, and the roof of the building is throughout
of non-combustible materials, the internal walls shall comply with the requirements for a separating
wall, except that the requirements of paragraphs (6) (a) and (b) of by-law 81 of these By-laws shall not
apply.
Fire-division of warehouses.
83. Buildings used predominantly for storage shall be divided internally with fire-division walls, so that,
no floor area exceeds 5,000 sq. ft. and no cubic capacity is greater than 250,000 cu. ft.
Fire-division walls.
84. (1) Every fire-division wall in a building shall comply with paragraphs (2), (4), (5), (6) and (7) of
by-law 81 of these By-laws and with paragraph (2) of this by law.
(2) In a building of the warehouse class for use wholly or predominantly for storage, the wall shall have
a fire resistance of four hours, and in any other building, it shall have a fire resistance of two hours.
Fire-division of offices.
85. No offices shall extend to more than 10,000 sq. ft. in area at any level of floor, unless separated
from all other parts of the same building by fire-division walls.
Walls separating flats.
86. A wall constructed for the separation of flats within a building (other than a load-bearing wall to
which by-law 87 of these By-laws applies) shall be non-combustible throughout and have a fire
resistance of-
(a) one hour if the building is a domestic building intended to be used wholly or predominantly
for human habitation and exceeds either 50 ft. in height or 2,500 sq. ft. on any one storey in
floor area;
(b) half an hour in any other case.
Fire resistance of floors, columns, beams and certain walls.
87. (1) In every building, other than a small house, which comprises more than one storey, and is of a
class and description specified in columns (1) and (2) of the following Table –
(a) every floor above the lowest storey;
(b) every load-bearing wall, other than an external wall, wall separating buildings or firedivision
wall;
(c) every column and beam, other than one to which by-law 92 of these By-laws applies; and
(d) every wall enclosing a common stairway or a lift shaft;
shall have the fire resistance specified in column (3) of the said Table in relation to the class and
description of a building specified in columns (1) and (2) respectively:
Provided that-
(i) where more than one period of fire resistance would be applicable, according to
whether regard is had to the height, floor area or capacity of the building, the longer or
longer period shall be taken to be the required period of fire resistance; and
(ii) where a building is completely separated into two or more parts by fire-division walls
complying with by-law 84 of these By-laws, or comprises two or more dwellings, shops
or other premises (not being individual flats) the requirement of this paragraph shall
apply to each such part, dwelling, shop or premises as if it were a separate building.
(2) Every opening in an internal wall enclosing a common stairway or a lift shaft shall, be protected by
doors or shutters having fire resistance of not less than half the period required for that wall but under
no circumstances the doors or shutters shall have a fire resistance of less than half an hour.
(3) In this by-law-
“common stairway” means a stairway intended for common use in a building for access to a
storey capable of being let in separate tenancies, or where more than ten persons are employed
on such storey; and
“floor area” means in relation to a building the floor area of any one storey in that building.
TABLE
Class of Building
(1)
Height, cubic capacity, floor area
(of any one storey)
(2)
Fire
Resistance
(3)
Domestic buildings intended to be
used wholly or predominantly for
human habitation
(a) Exceeding two storeys but not
exceeding 50 ft. in height, or
(b) Exceeding 1,000 sq. ft. but not
exceeding 2,500 sq. ft in floor
area
½ hour
(a) Exceeding 50 ft. in height, or
(b) Exceeding 2,500 sq. ft. in floor
area
1 hour
Domestic buildings not intended to
be used wholly or predominantly
for human habitation
(a) Exceeding 50 ft. but not
exceeding 75 ft. in height, or
(b) Exceeding 50,000 cu. ft. but not
exceeding 125,000 cu. ft in
capacity
½ hour
(a) Exceeding 75 ft. in height, or
(b) Exceeding 125,000 cu. ft. in
capacity
1 hour
Public buildings and buildings of
the warehouse class not used
wholly or predominantly for
storage
(a) Not exceeding 50 ft. in height, or
(b) Exceeding 50,000 cu. ft. but not
exceeding 125,000 cu. ft in
capacity
1/3 hour
(a) Exceeding 50 ft. but not
exceeding 75 ft. in height, or
(b) Exceeding 125,000 cu. ft. but not
exceeding 250,000 cu. ft. in
capacity, and not exceeding
7,500 sq. ft. in floor area
1 hour
(a) Exceeding 75 ft. in height, or
(b) Exceeding 250,000 cu. ft. in
capacity, or
(c) Exceeding 7,500 sq. ft. in floor
area
2 hours
Buildings of the warehouse class
used wholly or predominantly for
storage
(a) Exceeding 25 sq. ft. but not
exceeding 50 ft. in height, or
(b) Exceeding 25,000 cu. ft. but not
exceeding 50,000 cu. ft. in
capacity
¾ hour
Exceeding 50,000 cu. ft. but not
exceeding 125,000 cu. ft. in capacity
1 hour
(a) Exceeding 50 ft. but not
exceeding 75 ft. in height, or
(b) Exceeding 125,000 cu. ft. but not
exceeding 250,000 cu. ft. in
capacity and not exceeding
7,500 sq. ft. in floor area
2 hours
(a) Exceeding 75 ft. in height, or
(b) Exceeding 250,000 cu. ft. in
capacity, or
(c) Exceeding 7,500 sq. ft. in floor
area
4 hours
Ceilings of public buildings.
88. Public buildings of the types defined in Groups III and IV of the Sixth Schedule of these By-laws
have ceilings with half hour fire resistance, and where, required by the council on account of fire
hazard, similar provisions may be required for other public buildings.
Stairs for two or more dwellings.
89. In the case of a building containing two or more dwellings, every flight of stairs and every landing
forming part of a main stairway intended for common use by the occupants of two or more such
dwellings, shall comply with the requirements specified in column (2) of the Table set out below in
relation to the description of the building specified in column (1) of that Table.
TABLE
Description of building
(1)
Requirement of stairway
(2)
Exceeding 50 ft. in height or exceeding on any
one storey, 2,500 sq. ft. in floor area.
To be constructed of non-combustible material
having the same fire resistance as that required
for the walls of the building in which the stairs
are provided.
Neither exceeding 50 ft. in height nor exceeding
on any one storey, 2,500 sq. ft. in floor area.
To be constructed of non-combustible material,
or to have a fire resistance of one hour.
Fire Resistance – Miscellaneous Provisions Applying to all Buildings
Fire –stops in cavity walls.
90. (1) In every cavity wall built wholly of partly of combustible materials the cavity between any
leaves formed of or containing combustible material, shall be fire-stopped at the junction of the wall
with any other wall or with any floor, ceiling or roof and, if the wall exceeds 15 ft. length, at intervals of
not more than 15 ft.
(2) Any such cavity wall may be fire-stopped by blocking the cavity with non-combustible material.
Opening in external walls.
91. (1) Unless the council otherwise agrees, openings shall only be permitted in external walls, where
such walls are not within the distances prescribed hereunder from a plot boundary, other than one
abutting onto a street-
(a) 7 ft. 6 in. in a central area;
(b) 5ft. in any residential area; and
(c) 10 ft. in any other area.
Provided that on a return wall or one at right angles to the nearest plot boundary, the distance of the
opening from such boundary, may be reduced to 2 ft. 6 in. or if the separating wall projects 2 ft. beyond
the face of such return wall, the distance from the boundary may be reduced to the thickness of the
separating wall.
(2) In the case of a building, other than a dwelling house of not more than two storeys, where any part
of an opening in an external wall is vertically above an opening in an adjoining storey, suitable
provision shall be made to prevent the spread of fire from the lower to the upper opening.
(3) The requirements of paragraph (2) of this by-law shall be deemed to be satisfied if-
(a) The bottom of the higher opening is not less than 3 ft. above the top of the lower opening
and not less than 2 ft. above the upper surface of the floor separating the storeys; or
(b) A balcony of non-combustible material with a solid floor or some similar horizontal
protection is constructed between the two openings to project 2 ft. from the wall and extend
laterally beyond each limit of the overlap of the openings in such a way that-
(i) Where the lower or neither opening continues beyond that limit, for not less than 1 ft.;
and
(ii) Where the upper opening continues beyond that limit, for not less than 2 ft.
Structural members supporting certain walls.
92. Any part of a structural frame, any beam or column, carrying an external wall, a wall separating
buildings or a fire division wall, shall have the same fire resistance as that required by these By-laws for
the wall it carries.
External panel walls in frame structures.
93. Where the external walls of buildings on adjacent plots are contiguous with a common plot
boundary, and the walls are panel walls supported in a structural frame of metal or reinforced concrete
and otherwise fulfil the requirements for a separating wall, the requirements of by-law 81 of these bylaws
shall be satisfied, if the combined thickness of the panels provides the full fire resistance required
by these By-laws.
Roofs
Roofs – protection against fire.
94. (1) In every building of the warehouse class, in every public building or dwelling house exceeding
36,000 cu. ft. in capacity and in dwelling houses forming part of a block of more than two, the roof shall
be so covered as to afford adequate protection against the spread of fire into the building or to adjoining
buildings.
(2) In every building other than a building to which paragraph (1) of this by-law applies, the roof shall
be so covered, or to the building shall be so isolated from other buildings, as to afford adequate
protection against the spread of fire into the building or to adjoining buildings.
(3) A roof shall be deemed to satisfy the requirements of paragraphs (1) and (2) of this by-law, if it is
covered with any one or more of the following materials-
(a) natural slate, or slabs of stone;
(b) tiles of slabs of burnt clay or concrete;
(c) slates, tiles or sheets of asbestos cement;
(d) corrugated sheets of galvanized steel, or of other not less suitable material, of an approved
thickness;
(e) metal sheeting covered on both inner and outer surfaces with bituminous material, or a
similar approved weather-resisting protective covering;
(f) glass tiles or sheets, or glass bricks or blocks in concrete or metal frames;
(g) lead, copper, zinc or aluminium, of an approved thickness;
(h) asphalt mastic with sanded or gravelled finish containing not less than 83 per cent of mineral
matter and laid not less than ½ in. thick on a suitable base;
(i) asbestos based roofing felt which conforms with British Standard 747;
(j) organic based roofing felt covered with non-combustible material, not less than ½ in. thick,
or with bituminous macadam composed of fine gravel or stone chippings with not greater
than 7 per cent of bituminous material.
(4) A building shall be deemed to satisfy the requirements of paragraph (2) of this by-law as to
isolation, if the distance between the building and the boundary of the nearest adjacent plot is equal to
not less than twice the height of the building, except that in the case of a small house as defined in bylaw
71 if these By-laws, such distance may be reduced to 10 ft.
Roof access.
95. If a roof to which by-law 94 of these By-laws applies, has a ceiling, the latter shall be provided with
a door or scuttle to allow access to the roof space.
Roofs to be weatherproof.
96. The roof of a building shall be weatherproof.
Roof Coverings.
97. For roof coverings, the requirements of by-law 96 of these By-laws shall be satisfied if constructed
in accordance with the relevant Rules specified in the Fifth Schedule to these By-laws.
Source. https://kenya.eregulations.org/media/BUILDING%20CODE.pdf
