3.5.1 Requirements of external walls
The requirements of external walls are as follows:
a. Any external wall of a building or a separated part of a building which constitutes or is situated within a distance of 1m from any point on the relevant boundary, or is a wall of a building or a separated part of a building which exceeds 15m in height
shall:
(1) be constructed wholly of non-combustible materials apart from any external wall finishes which complies with Cl.3.5.4 or any internal lining which complies with Cl.3.13.4
(2) be so constructed as to attain the fire resistance required by this chapter; and
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Explanations & Illustrations
Clause 3.5.1 : Requirements of external walls
Figure 3.5.1a. - 1: Buildings of any height situated at 1m or less from relevant boundary
Figure 3.5.1a. - 2
Where the external wall of a building which exceeds 15m in building height or is within 1m of the relevant boundary, the entire external wall shall be constructed wholly of non-combustible materials, apart from any external combustible cladding under
Cl.3.5.4 or internal combustible lining under Cl.3.13.4.
The external wall of building which is sited less than 1m from the relevant boundary, shall be imperforate, free of any unprotected area and have the necessary fire resistance rating, both inside and outside. The required fire resistance shall be achieved
by the non-combustible part alone.
The external wall shall have the necessary fire resistance rating as required of the elements of structure of the building or compartment, in which the wall is located, in accordance with Table 3.3A, Part 1.
Any part of the external wall which is to be treated as unprotected area in accordance with Tables to Part II of Annex 3B to
Cl.3.5, need not have fire resistance.
If the entire external wall is to be treated as unprotected area, the separation distance between the external wall and the relevant boundary shall comply with Tables to Part II of Annex 3B to Cl.3.5.
External walls, which are more than 1m from the boundary, need to resist the effect of fire from the inside only.
In cases where the external walls of buildings are situated less than 1m from relevant boundary, the external walls shall be treated as separating walls. The requirements under Cl.3.6 shall be fully complied with.
b. any beam or column forming part of an external wall, and any structure carrying an external wall which is required to be constructed of non-combustible material, shall comply with the provisions of Cl.3.5.1a..
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Explanations & Illustrations
Clause 3.5.1b. : Requirements of external walls
( No illustration )
Any beam or column forming part of an external wall and any structure carrying an external wall shall be constructed of non-combustible materials and have the necessary fire resistance rating of elements of structure, apart from any external cladding
which complies with Cl.3.5.4 or any internal lining which complies with Cl.3.13.4. The required fire resistance shall be achieved by the non-combustible part alone.
3.5.2 Exceptions on external wall construction
a. The requirements of Cl.3.5.1a.(1) for non-combustibility of external walls need not apply to the external wall of a building or
part of a building separated as described in Cl.3.3.2b., if that wall is situated 1m or more from the relevant boundary
and it is:
(1) of PG I or II building of not more than three storeys, or
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Explanations & Illustrations
Clause 3.5.2a.(1) : Exceptions on external wall construction
-1.tmb-firecode.png?Culture=en&sfvrsn=29b901a9_1 "Fg.3.5.2a(1)-1")
Figure 3.5.2a.(1) - 1 : PG I / PG II building
-2.tmb-firecode.png?Culture=en&sfvrsn=6b50e843_1 "Fg.3.5.2a(1)-2")
Figure 3.5.2a.(1) - 2 : Separated part of PG I / PG II building
Part of a PG II building (not exceeding 3 storeys – building B in Figure 3.5.2a.(1) - 2, separated from the other parts (building A) by vertical compartment wall. Exemption would also apply to the building in Figure 3.5.2a.(1) - 1 which shall not exceed 3 storeys in height and be situated 1m or more from the relevant boundary.
(2) of single storey construction and not exceeding 15m in height and floor area not exceeding:
(a) 3000m2 for PG III, IV, VII buildings, or
(b) 2000m2 for PG V, VI buildings, or
(c) 500m2 for PG VIII buildings, or
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Explanations & Illustrations
Clause 3.5.2a.(2) : Exceptions on external wall construction
.tmb-firecode.png?Culture=en&sfvrsn=d08105e0_1 "Fg.3.5.2a(2)")
Figure 3.5.2a.(2)
Single storey health care occupancy, schools, old folk’s home, etc. (PG III) need not comply with non-combustibility of external wall, if it complies with the requirements under Cl.3.5.2a.(2).
(3) of other than single storey buildings, but not exceeding 7.5m in height and the compartmented floor area not exceeding:
(a) 250m2 for PG IV, V, VII buildings, or
(b) 150m2 for PG VI, VIII buildings.
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Explanations & Illustrations
Clause 3.5.2a.(3) : Exceptions on external wall construction
-1.tmb-firecode.png?Culture=en&sfvrsn=2bef7d7e_1 "Fg.3.5.2a(3)-1")
Figure 3.5.2a.(3) - 1
-2.tmb-firecode.png?Culture=en&sfvrsn=d7a24a64_1 "Fg.3.5.2a(3)-2")
Figure 3.5.2a.(3) - 2
Cl.3.5.2a.(3) is applicable to separated part of building as described in Cl.3.3.4b., which
is illustrated in Figure 3.5.2a.(3) - 2.
Part A of the building comprising shops which is separated from other parts of the same building by a continuous vertical compartment wall would qualify for exemption of non-combustibility of external construction if:
a. the entire external wall does not exceed 7.5m in height, measured from the outside ground; and
b. the external wall is situated 1m or more from the relevant boundary.
b. The requirements of Cl.3.5.1a.(2) for fire resistance of external walls need not apply to the external wall of a building or part
of a building separated as described in Cl.3.3.2b., if that wall is situated 1m or more from the relevant boundary and
it is:
(1) of a single storey building of a purpose group other than PG VI and VIII and not exceeding 15m in height, or
(2) of a single storey PG VI or VIII building not exceeding 15m in height and floor area not exceeding 2000m² or 500m² respectively.
3.5.3 Unprotected areas in any side of a building
Unprotected areas in any side of a building shall comply with all of the following:
a. Any relevant requirements relating to the permitted limits of unprotected areas specified in Annex 3B,
unless the building is so situated that such side can in accordance with Annex 3B,
consist entirely of any unprotected area.
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Explanations & Illustrations
Clause 3.5.3a. : Unprotected areas in any side of a building
( No illustration )
Unprotected areas in relation to a side or external wall of a building means:
a. a window, door or other opening, and
b. any part of the external wall which has less than the relevant fire resistance required in Cl.3.5, and
c. any part of the external wall which has combustible material more than 1mm thick attached or applied to its external face whether for cladding or any other purpose
The extent of unprotected areas in the external wall in relation to the setback from relevant boundary or lot boundary shall be in accordance with Annex 3B to Cl.3.5. The further the building is setback from the relevant boundary, the greater the amount of unprotected areas would
be permitted.
An example on calculations of unprotected openings/setback from relevant boundary is given in page 56. The intensity of the heat produced by a fire within a building which can reach the relevant boundary will depend upon the extent of the “unprotected
areas” in the external walls and the distance between these walls and the relevant boundary. The heat flux at the relevant boundary shall be less than that normally required for pilot ignition of combustible material after a period of exposure.
In situations where the extent of unprotected areas in external walls do not comply with Annex 3B,
the QP has 4 alternatives. These are:
a. reduce the total unprotected area, or
b. increase the distance from the relevant boundary, or
c. introduce compartmentation within the building to break up the size of enclosing rectangle, or
d. introduce automatic sprinkler system so that the unprotected areas can be doubled or the distance from the relevant boundary can be reduced by half.
b. The extent of unprotected openings in an external wall of a building/compartment, in relation to its distance from the lot boundary, can be doubled that of Annex 3B, provided the building/ compartment is fitted throughout with an automatic sprinkler system in compliance with the requirements in Chapter 6.
c. As an alternative to Cl.3.5.3b. above, the distance between the external wall of a building and the relevant boundary
can be half that specified in Annex 3B, if the building is fitted throughout
with an automatic sprinkler system in compliance with the requirements in Chapter 6.
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Explanations & Illustrations
Clause 3.5.3c. : Unprotected areas in any side of a building
( No illustration )
The above clause is to provide an alternative for buildings protected with sprinkler system. QP/Building owner shall decide which option, Cl.3.5.3b. or c. i.e. either double the unprotected openings or half the separation distance between the building and the relevant
boundary, whichever is relevant to the building.
d. The extent of unprotected openings in an external wall of a building/ part of building used for car parking in relation to its distance from the lot boundary/ relevant boundary can be based on the floor having the largest extent of unprotected openings
to comply with Table 1 of Annex 3B.
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Explanations & Illustrations
Clause 3.5.3d. : Unprotected areas in any side of a building
Section
Figure 3.5.3d. - 1
The above clause treats car park building differently by allowing the floor having the largest extent of unprotected openings to be used for the purpose of complying with Table 1 of Annex 3B.
This clause grants special relaxation in relation to its distance from the lot boundary for the purpose of complying with Table 1 of
Annex 3B.
In the above figure, the enclosing rectangle would apply to 1st storey elevation facing the relevant boundary, instead of the whole building, which forms one compartment.
Section
Figure 3.5.3d. - 2
The above clause treats car park building differently by allowing the floor having the largest extent of unprotected openings to be used for the purpose of complying with Table 1 of Annex 3B.
This clause grants special relaxation in relation to its distance from the lot boundary for the purpose of complying with Table 1 of
Annex 3B.
In the above figure, the enclosing rectangle would apply to 1st storey elevation facing the relevant boundary, instead of the whole building, which forms one compartment.
3.5.4 External wall finishes
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Rationale - Clause 3.5.4
This clause stipulates the requirements for cladding materials on the exterior of buildings. It also provides clarity on the rating and classification of that part of the building below 15m in height, and on the use of composite panels as cladding material.
Finishes on external walls shall comply with the following:
a. Homogenous cladding on external walls shall be constructed of material of at least limited combustibility tested in accordance with BS 476 Part 11 or approved equivalent. For buildings not within PG VI and VIII, any part of such cladding below a height of 15m from the ground, and situated at least 1m away from the relevant boundary can consist of:
(1) timber of not less than 9mm finished thickness, or
(2) a material having a surface which achieves at least:
(a) Class 0 flame-spread rating tested in accordance with BS 476 Part 6 & 7, or
(b) Class B rating classified under EN 13501-1.
b. Composite panels used as cladding on external walls shall comply with Cl.3.15.13.
3.5.5 Reference to Part I & II of Annex 3B
Any reference to Annex 3B shall be construed as referring to the provisions of Part
I of that Annex together with the provisions of Part II.
3.5.6 Buildings on land in common occupation
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Explanations & Illustrations
Clause 3.5.6. : Buildings on land in common occupation
Figure 3.5.6
1. It is necessary to assume a notional boundary when two or more detached buildings are erected on land in common occupation.
2. The notional boundary is taken to exist in space between the buildings and is positioned so that the external walls of building A and B facing the notional boundary comply with the separation distance requirement in accordance with Tables of
Annex 3B, based on the percentage of unprotected area and the purpose group of
the compartment/floor.
3. Unprotected openings shall be assessed for each building separately. The separation distance between the two buildings shall be not less than the sum of the distance each building would require to a relevant boundary i.e. “a” is equal to
or greater than the separation distance to the boundary for building A and “b” is equal to or greater than the separation distance to the relevant boundary for building B.
4. The notional boundary can be shifted next to external wall of building A or B, if the external wall has no unprotected areas and is constructed of non-combustible materials having the requisite period of fire resistance rating as the elements of structure
of the storey compartment.
If two or more detached buildings are erected on land in common occupation, for any external wall of such a building facing the external wall of an adjacent building, the relevant boundary shall be a notional boundary passing between those buildings.
This notional boundary shall be positioned to enable the external walls of those buildings to comply with the requirements of Cl.3.5.3.
3.5.7 Vertical fire spread
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Rationale - Clause 3.5.7
The purpose of providing high/low separation is to ensure fire will not spread from the lower compartment to the abutting higher different compartment of the building.
a. For high and low parts of different compartments of a building abutting each other, either one of the following requirements shall be complied with to prevent spread of fire between the distinct parts:
(1) the roof-over of the lower part of the building shall be fire-rated in accordance with the element of structure for minimum 1 hr for a distance of 5m measured horizontally from the external wall of the higher part of building; or
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Explanations & Illustrations
Clause 3.5.7a.(1) : Vertical fire spread
.tmb-firecode.png?Culture=en&sfvrsn=f878ef88_1 "Fg.3.5.7a(1)")
Section
Figure 3.5.7a.(1)
The entire roof projection over the lower part of the building if less than 5m, then the entire roof projection shall be fire-rated with minimum 1-hr fire resistance rating. A fire occurring in the 3rd storey would spread vertically to 4th storey via the roof and windows. To prevent the fire spread vertically, the roof of 3rd storey should be fire-rated for minimum. 1 hour for a distance of 5m measured horizontally from the external wall of 4th storey abutting the roof of 3rd storey. The above requirement to fire rate the roof of 3rd storey will not be applicable if the building or lower part of the building is sprinkler-protected.
(2) the external wall of the higher part of the building overlooking the roof below shall have the necessary fire resistance rating in accordance with the element of structure for minimum 1 hr for a vertical height of not less than 9m measured from the roof of the lower part of the building.
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Explanations & Illustrations
Clause 3.5.7a.(2) : Vertical fire spread
-1.tmb-firecode.png?Culture=en&sfvrsn=a3be379_1 "Fg.3.5.7a(2)-1")
Section
Figure 3.5.7a.(2) - 1
-2.tmb-firecode.png?Culture=en&sfvrsn=8bf36d9b_1 "Fg.3.5.7a(2)-2")
Section
Figure 3.5.7a.(2). - 2
Providing fire rated wall with unprotected opening is an alternative to fire rating the roof under Cl.3.5.7a..
The above 2 figures show the 2 ways of preventing fire spread vertically from the lower floor to the upper floors.
b. The above requirements shall not be applicable to:
(1) buildings or lower parts of the building which are sprinkler-protected;
(2) the buildings under the conservation programme of the authority having jurisdiction, or buildings built before 1969;
(3) covered car porches intended solely for the purpose of the boarding and alighting of passengers;
(4) open-sided/ covered walkways/ linkways not exceeding 5m in width with no commercial activities or storage; and
(5) canopies of depth not exceeding 2m over private enclosed spaces or balconies in PG II buildings,
provided that the canopy is constructed of non-combustible material.
Effective Date: 10 May 2019
Amendment History
| 3.5.7b.(3) to (5) |
10 May 2019 |
10 May 2019 |
Change in requirements |
3.5.7b.(5) canopies over private enclosed spaces or balconies in PG II buildings, provided that the canopy is constructed of non-combustible material . |
10 May 2019 |
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3.5.8 Non-sprinkler-protected roof
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Rationale - Clause 3.5.8
This fire safety requirement is to prevent fire from spreading through an unprotected roof to an adjacent building located outside the boundary.
The 4m setback stipulated is consistent with the minimum horizontal 5m protection required under Cl.3.5.7a.(1) to prevent vertical fire spread, taking into consideration a minimum 1m setback of the adjacent building from the boundary.
For non-sprinkler-protected roof within 4m from the boundary (excluding boundary abutting public street, canal or river), the portion of the roof within this 4m zone shall be 1-hr fire-rated. This requirement is exempted for areas stated under Cl.3.5.7b..
3.5.9 Separation of residential floor facade
Effective Date: 25 Aug 2023
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Rationale - Clause 3.5.9
The fire-rated spandrel and horizontal projection from building facade are to serve as an effective fire barrier to slow down or prevent vertical fire spread. The dimensions have been validated through a fire engineering study.
Amendment History
| 3.5.9 (dated 25 Aug 2023) |
25 Aug 2023 |
25 Aug 2023 |
Revised/Clarifications |
3.5.9 Separation of residential floor façade
(Relocated to Cl.9.2.1b.(3)) |
25 Aug 2023 |
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|
| 3.5.9( dated 15 Sep 2020) |
15 Mar 2021 |
15 Mar 2021 |
Revised & Relocated |
Separation of residential floor facade The facade of residential floors above 24m habitable height shall be separated from each other by: a. a 1-hr fire-rated spandrel of at least 1.5m in height, or b. a 1-hr fire-rated horizontal projection that extends at least 600mm from the building. |
15 Sep 2020 |
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Separation of PG II residential floor façade shall be in accordance with Cl.9.2.1b.(3).
3.5.10 External sun-breakers/ weather features
External sun-breakers or weather features which will result in the channelling of flame upwards during a fire are not permitted.
