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Legend: Explanations & Illustrations Rationale Note Revision history Print

ANNEX 3A - NOTIONAL PERIODS OF FIRE RESISTANCE

A1.0 General

In this Annex:

a. “Class 1 aggregate” means foamed slag, pumice, blast furnace slag, pelleted fly ash, crushed brick and burnt clay products (including expanded clay) well-burnt clinker and crushed limestone.

b. “Class 2 aggregate” means flint gravel, granite, and all crushed natural stones other than limestones.

c. Any reference to plaster means:

(1) in the case of an external wall 1m or more from the relevant boundary, plaster applied on the internal face only;

(2) in the case of any other wall, plaster applied on both faces;

(3) if to plaster of a given thickness on the external face of a wall, except in the case of a reference to vermiculite-gypsum plaster, rendering on the external face of the same thickness; and

(4) if to vermiculite-gypsum plaster, vermiculite-gypsum plaster of a mix within the range of 1½ to 2:1 by volume.

d. In the case of a cavity wall, the load is assumed to be on inner leaf only except for fire resistance period of 4-hrs.

e. Any material or type of construction and its method of preparation or application as referred to in the table, shall conform with the relevant provisions of the Building Control Act (Chapter 29) and the relevant Singapore Standard or Singapore Standard Code of Practice. In the absence of the aforementioned Standard or Code of Practice, the relevant British equivalent or other accepted standard or codes of practice shall be applicable.

A2.0 : WALLS
Construction and MaterialsMinimum thickness excluding plaster (in mm) for period of fire resistance of
Load-bearingNon-load-bearing
4 hrs3 hrs2 hrs1½ hrs1 hr½ hr4 hrs3 hrs2 hrs1½ hrs1 hr½ hr
A2.1 -- Mansonry Construction
1. Reinforced concrete, minimum concrete cover to main reinforcement of 25mm:











(a) Unplastered (to comply with SS EN 1992–1–2)------------
(b) 12.5mm cement-sand plaster180-1001007575------
(c) 12.5mm gypsum-sand plaster180-1001007575------
(d) 12.5mm vermiculite-gypsum plaster125-75756363------
2. No-fines concrete of Class 2 aggregate:











(a) 13mm cement-sand plaster------150150150150150150
(b) 13mm gypsum-sand plaster------150150150150150150
(c) 13mm vermiculite-gypsum plaster------150150150150150150
3. Bricks of clay, concrete or sand-lime:











(a) Unplastered2002001001001001001701701001007575
(b) 13mm cement-sand plaster2002001001001001001701701001007575
(c) 13mm gypsum-sand plaster2002001001001001001701701001007575
(d) 13mm vermiculite-gypsum or perlite-gypsum* plaster100-100100100100100-1001007575
4. Concrete blocks of Class 1 aggregate:











(a) Unplastered150-100100100100150-75757550
(b) 12.5mm cement-sand plaster150-100100100100150-75757550
(c) 12.5mm gypsum-sand plaster150-100100100100150-75757550
(d) 12.5mm vermiculite-gypsum plaster 100-10010010010075-75625050
5. Concrete blocks of Class 2 aggregate:











(a) Unplastered--100100100100150-1001007550
(b) 12.5mm cement-sand plaster--100100100100150-1001007550
(c) 12.5mm gypsum-sand plaster--100100100100150-1001007550
(d) 12.5mm vermiculite-gypsum plaster100-100100100100100-75757550
6. Autoclaved aerated concrete blocks, density 475 - 1200 kg/m3180 140 100 100 100 100 100 - 62 62 50 50
7. Hollow concrete blocks, one cell in wall thickness, of Class 1 aggregate:











(a) Unplastered--100100100100150-10010010075
(b) 12.5mm cement-sand plaster--100100100100150-100757575
(c) 12.5mm gypsum-sand plaster--100100100100150-100757575
(d) 12.5mm vermiculite-gypsum plaster--100100100100150-75756262
8. Hollow concrete blocks, one cell in wall thickness, of Class 2 aggregate:











(a) Unplastered------150-150125125125
(b) 12.5mm cement-sand plaster------150-150125125100
(c) 12.5mm gypsum-sand plaster------150-150125125100
(d) 12.5mm gypsum-sand plaster------125-10010010075
9. Cellular clay blocks not less than 50% solid











(a) 12.5mm cement-sand plaster----------10075
(b) 12.5mm gypsum-sand plaster----------10075
(c) 12.5mm vermiculite-gypsum plaster------200-10010010062
10. Cavity wall with outer leaf of bricks or blocks of clay, composition, concrete or sand-lime, not less than 100mm thick and;            
(a) inner leaf of bricks or blocks of clay, composition, concrete or sand lime10010010010010010075-75757575
(b) inner leaf of solid or hollow concrete bricks or blocks of Class 1 aggregate10010010010010010075-75757575
11. Cavity wall with outer leaf of cellular clay blocks as 9 above and inner leaf of autoclaved aerated concrete blocks, density 480-1200 kg/m3150 140 100 100 100 100 75 75 75 75 75 75
* = Perlite-gypsum plaster to clay bricks only
A2.0 : WALLS
Construction and Materials

Period of Fire Resistance

hrs

A2.2 - Framed and Composite Construction (non-load-bearing)
1. Steel frame with external cladding of 16mm rendering on metal lathing and internal lining of autoclaved aerated concrete blocks, density 480-1120 kg/m3 of thickness of – 
(a) 50mm2
(b) 62mm3
(c) 75mm4
2. Steel frame with external cladding of 100mm concrete blocks and internal lining of 16mm gypsum plaster on metal lathing4
3. Steel frame with external cladding of 16mm rendering on metal lathing and internal lining of 16mm gypsum plaster on metal lathing1
4. Steel or timber frame with facings on each side of - 
(a) metal lathing with cement-sand or gypsum plaster of thickness of- 
(1) 19mm1
(2) 12.5mm½
(b) metal lathing with vermiculite-gypsum or perlite-gypsum plaster of thickness of- 
(1) 25mm2
(2) 19mm
(3) 12.5mm1
(c) 9.5mm plasterboard with gypsum plaster of thickness of 5mm½
(d) 9.5mm plasterboard with vermiculite-gypsum of thickness of- 
(1) 25mm2
(2) 16mm
(3) 10mm1
(4) 5mm½
(e) 12.5mm plasterboard 
(1) unplastered½
(2) with gypsum plaster of thickness of 12.5mm1
(f) 12.5mm plasterboard with vermiculite-gypsum plaster of thickness of- 
(1) 25mm2
(2) 16mm1 ½
(3) 10mm1
(g) 19mm plasterboard (or two layers of 9.5mm fixed to break joint) without finish1
(h) 19mm plasterboard for two layers of 9.5mm with vermiculite-gypsum plaster of thickness of- 
(1) 16mm2
(2) 10mm1 ½
(i) 12.5mm fibre insulating board with gypsum plaster of thickness of 12.5mm½
(j) 25mm wood wool slabs with gypsum plaster of thickness of 12.5mm1
5. Compressed straw slabs in timber frames finished on both faces with gypsum plaster of thickness of 5mm1
6. Plasterboard 9.5mm cellular core partition- 
(a) unplastered½
(b) 12.5mm gypsum plaster½
(c) 22mm vermiculite-gypsum plaster2

7. Plasterboard 12.5mm cellular core partition-

 
(a) unplastered½
(b) 12.5mm gypsum plaster1
(c) 16mm vermiculite-gypsum plaster2
8. Plasterboard 19mm finished on both faces with 16mm gypsum plaster1
9. Plasterboard 12.5mm bonded with neat gypsum plaster to each side of 19mm plasterboard1
10. Three layers of 19mm plasterboard bonded with heat gypsum plaster2
11. Wood wool slab with 12.5mm rendering or plaster of thickness of- 
(a) 75mm2
(b) 50mm1
12. Compressed straw slabs, with 75mm by 12.5mm wood cover strips to joints, of thickness of 50mm½

Note :

* = The presence of a combustible vapour barrier within the thickness of these constructions shall not be regarded as affecting these periods of fire resistance

A2.0 : WALLS
Construction and Materials

Period of Fire Resistance

hrs

A2.3 - External walls (non-loadbearing) more than 1m from the relevant boundary
1. Steel frame with external cladding of non-combustible sheets and internal lining of-
(a) 12.5mm cement-sand or gypsum plaster on metal lathing4
(b) two layers of 9.5mm plasterboard½
(c) 9.5mm plasterboard finished with gypsum plaster of thickness of 12.5mm½
(d) 12.5mm plasterboard finished with 5mm gypsum plaster½
(e) 50mm compressed straw slabs½
(f) 50mm compressed straw slabs finished with 5mm gypsum plaster2
2 *Timber frame with external cladding of 10mm cement-sand or cement-lime rendering and internal lining of-
(a) 16mm gypsum plaster on metal lathing1
(b) 9.5mm plasterboard finished with12.5 mm gypsum plaster1
(c) 12.5mm plasterboard finished with 5mm gypsum plaster1
(d) 50mm compressed straw slabs1
(e) aerated concrete blocks1
(1) 50mm3
(2) 62mm4
(3) 75mm4
(4) 100mm4
3 Timber frame with external cladding of 100mm clay, concrete or sand-lime bricks of blocks, finished internally with 16mm gypsum plaster on metal lathing4
4. *Timber frame with external cladding of weather boarding or 9.5 mm plywood and internal lining of-
(a) 16mm gypsum plaster on metal lathing½
(b) 9.5mm plasterboard finished with 12.5mm gypsum plaster½
(c) 12.5mm plasterboard finished with 5mm gypsum plaster½
(d) 50mm compressed straw slabs½
(e) aerated concrete blocks- 
(1) 50mm3
(2) 62mm4
(3) 75mm4
(4) 100mm4

Note :

* = The presence of a combustible vapour barrier within the thickness of these constructions shall not be regarded as affecting these periods of fire resistance

A3.0 : REINFORCED CONCRETE BEAMS
DescriptionMinimum Dimension (in mm) of Concrete to give a Fire Resistance of:-
4 hrs3 hrs2 hrs1 ½ hrs1 hr½ hr
1 Siliceous aggregate concrete:
(a) average concrete cover to main reinforcement65*55*45*352515
(b) beam width28024018014011080
2. As (1) with cement or gypsum plaster 15mm thick on light mesh reinforcement
(a) average concrete cover to main reinforcement50*4030201515
(b) beam width2502101701108570
3. As (1) with vermiculite/gypsum plaster+ 15mm thick:
(a) average concrete cover to main reinforcement251515151515
(b) beam width175145125856060
4. Light weight aggregate concrete:
(a) average concrete cover to main reinforcement504535302015
(b) beam width25020016013010080

Note:

* = Supplementary reinforcement, to hold the concrete cover in position, may be necessary.

+ = Vermiculite/gypsum plaster should have a mix ratio in the range of 1 ½ - 2 : 1 by volume.

A4.0 : PREstressED CONCRETE BEAMS
DescriptionMinimum Dimension (in mm) of Concrete to give a Fire Resistance of:-
4 hrs3 hrs2 hrs1 ½ hrs1 hr½ hr
1 Siliceous aggregate concrete:
(a) average concrete cover to tendons100*85*65*50*4025
(b) beam width28024018014011080
2. As (1) with vermiculite concrete slabs 15mm thick , used as permanent shuttering :
(a) average concrete cover to tendons75*6045352515
(b) beam width2101701251007070
3. As (2) but with 25mm thick slabs:
(a) average concrete cover to tendons655035251515
(b) beam width180140100706060
4. As (1) with 15mm thick gypsum plaster with light mesh reinforcement:
(a) average concrete cover to tendons90*7550403015
(b) beam width2502101701108570
5. As (1) with vermiculite/gypsum plaster+ 15m thick:
(a) average concrete cover to tendons75*6045302515
(b) beam width170145125856060
6. As (5) but with 25mm thick coating:
(a) average concrete cover to tendons504530251515
(b) beam width14012585706060
7. Lightweight aggregate concrete:
(a) average concrete cover to tendons806550403020
(b) beam width25020016013010080

Note:

* = Supplementary reinforcement, to hold the concrete cover in position, may be necessary.

+ = Vermiculite/gypsum plaster should have a mix ratio in the range of 1 ½ - 2 : 1 by volume.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A5.0 : REINFORCED CONCRETE COLUMNS
DescriptionMinimum Dimension (in mm) of Concrete to give a Fire Resistance of:-
4 hrs3 hrs2 hrs1½ hrs1 hr½ hr
A5.1 - All Face Exposed
1. Siliceous aggregate concrete:
(a) without additional protection450400300250200150
(b) with cement or gypsum plaster 15mm thick on light mesh reinforcement300275225150150150
(c) with vermiculite / gypsum plaster*275225200150120120
2. Limestone aggregate concrete or siliceous aggregate:
(a) concrete with supplementary reinforcement in concrete cover300275225200190150
3. Lightweight aggregate concrete300275225200150150
A5.2 - One Face Exposed
1. Siliceous aggregate concrete
(a) without additional protection1801501001007575
(b) with vermiculite/ gypsum plaster* 15mm thick on exposed faces12510075756565

Note:

+ = Vermiculite/gypsum plaster should have a mix ratio in the range of 1 ½ - 2 : 1 by volume.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A6.0 : STRUCTURAL STEEL
A6.1 - Encased Steel Stanchions (Mass per metre not less than 45kg)
DescriptionMinimum Thickness (in mm) of Protection for a Fire Resistance of :
4 hrs3 hrs2 hrs1 ½hrs1 hr½hr
A. Solid Protection* (unplastered)
1. Concrete not leaner than 1:2:4 mix with natural aggregates-
(a) concrete not assumed to be load- bearing reinforced+50-25252525
(b) concrete assumed to be load-bearing, reinforced in accordance with SS EN 1992 and SS EN 199475-50505050
2. Solid bricks of clay, composition or sand-lime1007550505050
3. Solid blocks of foamed slag or pumice concrete reinforced+ in every horizontal joint756050505050
4. Sprayed vermiculite-cement--38321912.5
B. Hollow Protection++
1. Solid bricks of clay, composition or sand-lime reinforced in every horizontal joint, unplastered115-50505050
2. Solid blocks of foamed slag or pumice concrete reinforced+ in every horizontal joint, unplastered75-50505050
3. Metal lathing with gypsum or cement- lime plaster of thickness of ---38§251912.5
4. Metal lathing :-      
(a) with vermiculite-gypsum or perlite-gypsum plaster of thickness of50§-191612.512.5
(b) spaced 25mm from flanges with vermiculite-gypsum or perlite-gypsum plaster of thickness of44-1912.512.512.5
5. Gypsum plasterboard with 1.6mm wire binding at 100mm pitch -
(a) 9.5mm Plasterboard with gypsumplaster of thickness of----12.512.5
(b) 19mm Plasterboard with gypsum plaster of thickness of--12.51077
6. Gypsum plasterboard with 1.6mm wire binding at 100mm pitch-
(a) 9.5mm plasterboard with vermiculite-gypsum plaster of thickness of--16151010
(b) 19mm plasterboard with vermiculite-gypsum plaster of thickness of38§-20131010
7. Vermiculite-cement slabs of 4:1 mix reinforced with wire mesh and finished with plaster skim. Slabs of thickness of63-25252525

Note:

* = Solid protection means a casing which is bedded close to the steel without intervening cavities and with all joints in that casing made full and solid.

+ = Reinforcement shall consist of steel binding wire not less than 2.3mm in thickness, or a steel mesh weighing not less than 0.48 kg/m2. In concrete protection, the spacing of that reinforcement shall not exceed 150mm in any direction

++ = Hollow protection means that there is a void between the protective material and the steel. All hollow protection to columns shall be effectively sealed at each floor level.

§ = Light mesh reinforcement required 12.5mm to 19mm below surface unless special corner beads are used.

 
 
 
 
 
 
 
 
A6.2 - Encased Steel Beams (Mass per metre not less than 30kg)
DescriptionMinimum Thickness (in mm) of Protection for a Fire Resistance of :
4 hrs3 hrs2 hrs1½ hrs1 hr½ hr
A. Solid Protection+ (unplastered)
1. Concrete not leaner than 1:2:4 mix with natural aggregates-
(a) concrete not assumed to be load- bearing , reinforced++755025252525
(b) concrete assumed to be load-bearing, reinforced in accordance with SS EN 1992 and SS EN 1994757550505050
2. Sprayed vermiculite - cement--38321912.5
B. Hollow Protection++
1. Metal lathing -
(a) with cement-lime plaster of thickness of--38251912.5
(b) with gypsum plaster of thickness of--22191612.5
(c) with vermiculite-gypsum or perlite-gypsum plaster of thickness of32-12.512.512.512.5
2. Gypsum plasterboard with 1.6mm wire binding at 100mm pitch-
(a) 9.5mm plasterboard with gypsum plaster of thickness of----12.512.5
(b) 19 mm plasterboard with gypsum plaster of thickness of--12.51077
3. Plasterboard with 1.6mm wire at 100m pitch -
(a) 9.5mm plaster nailed to wooden cradles finished with gypsum plaster of thickness of-----12.5
(b) 9.5mm plasterboard with vermiculite -gypsum plaster of thickness of--16151010
(c) 19mm plasterboard with vermiculite-gypsum plaster of thickness of32-101077
(d) 19mm plasterboard with gypsum plaster of thickness of--20131010
4. Vermiculite-cement slabs of 4:1 mix reinforced with wire mesh and finished with plaster skim. Slabs of thickness of63-25252525
5. Gypsum-sand plaster 12.5mm thick applied to heavy duty (Type B as designated in EN 13168) Wood wool slabs of thickness of--50383838

Note:

* = Hollow protection means that there is a void between the protective materials and the steel. All hollow protection to columns shall be effectively sealed at each floor level.

+ = Solid protection means a casing which is bedded close to the steel without intervening cavities and with all joints in that casing made full and solid.

++ = Reinforcement shall consist of steel binding wire not less than 2.3mm in thickness, or a steel mesh weighing not less than 0.48 kg/m2. In concrete protection, the spacing of that reinforcement shall not exceed 150mm in any direction.

§ = Light mesh reinforcement required 12.5mm to 19mm below surface unless special corner beads are used.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
A7.0 : STRUCTURAL ALUMINIUM
DescriptionMinimum Thickness (in mm) of Protection for a Fire Resistance of :
4 hrs3 hrs2 hrs1½ hrs1 hr½ hr
A7.1 - Solid Protection*
1. Sprayed vermiculite-cement----4419
A7.2 - Hollow Protection+
1. Metal lathing with vermiculite-gypsum or perlite-gypsum plaster of thickness of--32221612.5
2. Metal lathing finished with neat gypsum plaster of thickness of----1912.5
3. Gypsum plasterboard 19mm thick with 1.6 mm wire binding at 100mm pitch finished with gypsum-vermiculite plaster of thickness of--22161010

Note:

* = Solid protection means a casing which is bedded close to the alloy without intervening cavities and with all joints in that casing made full and solid.

+ = Hollow protection means that there is a void between the protected material and the alloy. All hollow protection to columns shall be effectively sealed at each floor level

A8.0 : TIMBER FLOORS
Construction and materialsMinimum Thickness (in mm) of Protection for a Fire Resistance of :
1 hr½ hr

modified++ ½ hr

1. Plain edge boarding on timber joists not less than 38mm wide with ceiling of -
(a) timber lath and plaster - thickness of plaster-1616
(b) timber lath and plaster with plaster of minimum thickness of 16mm covered on underside with plasterboard of thickness-12.5-
(c) metal lathing and plaster - thickness of plaster   
(1) gypsum-16-
(2) vermiculite-12.5-
(d) one layer of plasterboard of thickness--12.5
(e) one layer of plasterboard of minimum thickness of 9.5mm finished with gypsum plaster of thickness--12.5
(f) one layer of plasterboards of minimum thickness of 12.5mm finished with gypsum plaster of thickness-12.5-
(g) two layers of plasterboard of total thickness-2519
(h) one layer of fibre insulating board of minimum thickness of 9.5mm finished with gypsum plaster of thickness-5-
(i) one layer of fibre insulating board of minimum thickness of 12.5mm finished with gypsum plaster of thickness--12.5
(j) wood wool slab 25mm thick finished with gypsum plaster of thickness-5-
2. Tongued and grooved boarding of not less than 16mm (finished) thickness* on timber joists not less than 38 mm wide ceiling of -
(a) timber lath and plaster - thickness of plaster--16
(b) timber lath and plaster with plaster of minimum thickness of 16mm covered on underside with plasterboard of thickness-9.5-
(c) metal lathing and plaster - thickness of plaster   
(1) gypsum2216-
(2) vermiculite12.512.5-
(d) one layer of plasterboard of thickness --9.5
(e) one layer of plasterboard of minimum thickness of 9.5mm finished with-
(1) gypsum plaster of thickness -12.5-
(2) vermiculite-gypsum plaster of thickness12.5--
(f) one layer of plasterboards of minimum thickness of 12.5mm finished with gypsum plaster of thickness-5-
(g) two layers of plasterboard of total thickness-22-
(h) one layer of fibre insulating board of minimum thickness of 9.5mm finished with gypsum plaster of thickness--5
(i) wood wool slab 25mm thick finished with -
(1) gypsum plaster of thickness -5-
(2) vermiculite - gypsum plaster of thickness10--
3. Tongued and grooved boardings of not less than 21mm (finished) thickness* on timber joists not less than 
(a) timber lath and plaster - thickness of plaster -16-
(b) metal lathing and plaster - thickness of plaster-16-
(c) one layer of plasterboard of thickness--9.5
(d) one layer of plasterboard of minimum thickness of 9.5mm finished with -
 (1) gypsum plaster of thickness -12.5-
 (2) vermiculite-gypsum plaster of thickness12.5--
(e) one layer of plasterboard of minimum thickness of 12.5mm finished with gypsum plaster of thickness -5-
(f) two layers of plasterboard of total thickness -19-
(g) one layer of fibre insulating board of thickness --12.5
(h) one layer of fibre insulating board of minimum thickness of 12.5mm finished with gypsum plaster of thickness-12.5-
(i) wood wool slab 25mm thick finished with -
(1) gypsum plaster of thickness -5-
(2) vermiculite-gypsum plaster of thickness10--

Note:

* = Or an equivalent thickness of wood chipboard

++ = The term “modified ½ hour” refers to the requirements specified in item 3(a) of Table 3.4A

 
 
 
 
 
 
 
 
A9.0 : REINFORCED CONCRETE FLOORS (SILICEOUS OR CALCAREOUS AGGREGATE)
Floor ConstructionMinimum Dimension (in mm) to give Fire Resistance of :
4 hrs3 hrs2 hrs1 ½ hrs1 hr½ hr
Solid slabAverage cover to reinforcement252520201515
Depth, overall+150150125125100100
Cored slabs in which the cores are circular or are higher than wide. Not less than 50% of the gross across section of the floor should be solid materialAverage cover to reinforcement252520201515
Thickness under cores504040302520
Depth, overall+190175160140110100
Hollow box section with one or more longitudinal cavities which are wider than highAverage cover to reinforcement252520201515
Thickness of bottom flange504040302520
Depth, overall+230205180155130105
Ribbed floor with hollow infill blocks of clay, or inverted T-section beams with hollow infill blocks of concrete or clay. A floor in which less than 50% of the gross cross section is solid material must be provided with a 15mm plaster coating on soffitAverage cover to reinforcement252520201515
Width or rib, or beam, at soffit12510090807050
Depth, overall+190175160140110100
Upright T-sectionAverage bottom cover to reinforcement65*55*45*352515
Side cover to reinforcement655545352515
Least width or down-standing leg150140115907560
Thickness of flange+15015012512510090
Inverted channel sections with radius at intersection of soffits with top of leg not exceeding depth of sectionAverage bottom cover to reinforcement65*55*45*352515
Side cover to reinforcement403025201510
Least width or down-standing leg757060454030
Thickness at crown+15015012512510090
Inverted channel sections or U-sections with radius at intersection of soffits with top of leg exceeding depth of sectionAverage bottom cover to reinforcement65*55*45*352515
Side cover to reinforcement403025201510
Least width or down-standing leg706050403525
Thickness at crown+1501501001007565

* = Supplementary reinforcement, to hold the concrete cover in position, may be necessary.

+ = Non-combustible screeds and finishes may be included in these dimensions.

A10.0 : PRESTRESSED CONCRETE FLOORS (SILICEOUS OR CALCAREOUS AGGREGATE)
Floor ConstructionMinimum Dimension (in mm) to give Fire Resistance of :
4 hrs3 hrs2 hrs1 ½ hrs1 hr½ hr
Solid slabAverage cover to tendons65*50*40302515
Depth, overall+ 15015012512510090
Cored slabs in which the cores are circular or are higher than wide. Not less than 50% of the gross across section of the floor should be solid materialAverage cover to tendonst65*50*40302515
Thickness under cores504040302520
Depth, overall+190175160140110100
Hollow box section with one or more longitudinal cavities which are wider than highAverage cover to tendons65*50*40302515
Thickness of bottom flange655040302525
Depth, overall+230205180155130105
Ribbed floor with hollow infill blocks of clay, or inverted T-section beams with hollow infill blocks of concrete or clay. A floor in which less than 50% of the gross cross section is solid material must be provided with a 15mm plaster coating on soffitAverage cover to tendons65*50*40302515
Width or rib, or beam, at soffit12510090807050
Depth, overall+190175160140110100
Upright T-sectionAverage bottom cover to tendons100*85*65*50*4025
Side cover to tendons1008565504025
Least width or down-standing leg2502001501109060
Thickness of flange+15015012512510090
Inverted channel sections with radius at intersection of soffits with top of leg not exceeding depth of sectionAverage bottom cover to tendons100*85*65*50*4025
Side cover to tendons504535252010
Least width or down-standing leg12510075554530
Thickness at crown+15015012512510090
Inverted channel sections or U-sections with radius at intersection of soffits with top of leg exceeding depth of sectionAverage bottom cover to tendons100*85*65*50*4025
Side cover to tendons504535252015
Least width or down-standing leg1109070504530
Thickness at crown+15015012512510090

* = Supplementary reinforcement, to hold the concrete cover in position, may be necessary.

+ = Non-combustible screeds and finishes may be included in these dimensions.

A11.0 : GLAZING
Construction and materialsMinimum Thickness (in mm) of Glazing for a Period of :-
1 hr½ hr
1. Glass, in direct combination with metal, the melting point of which is not lower than 982.2°C, in square not exceeding 0.015m2 in area
Thickness of glass-6.35
2. Glass reinforced with wire not less than 0.46mm in diameter laid to a square mesh measuring 12.70mm from centre to centre of wire, and electrically welded at the intersections, or laid to a hexagonal mesh measuring 25.40mm across the flat side
Thickness of glass-6.35
In windows, doors , borrowed lights, lanterns and skylights, glass complying with paragraphs 1 or 2 of this Table shall be fixed with wood or metal beads or with a glazing compound in conjunction with sprigs or clips in panels not exceeding 0.372m2 in area in timber frames (fixed shut) having a minimum width and thickness of 44.45mm clear of rebates
3. Glass reinforced with wire as in paragraph 2 of this Table, in windows, doors, borrowed lights, lanterns and skylights, fixed with metal beads in panels not exceeding 1.115m2 in metal frames (fixed shut) all metal having a melting point not lower than 982.2oC, the thickness of glass6.356.35
4. Glass bricks or blocks in walls
Laid in cement / lime / sand mortar with light wire reinforcing mesh in every third horizontal joint in a panel not exceeding 2.438m in width or height set along the sides and head into recesses in the surrounding non-combustible construction. The depth of such recessed shall be not less than 25.40mm, the glass blocks extending into the recesses to a depth of 12.70mm and bedded upon layer of glass fibre. A non-hardening mastic shall be used to fill the spaces between the sides of the recesses and the faces of the panels-98.43

Note:

In this Table the absence of a figure in a period column indicated that glazing described is not acceptable for the period applicable to that column.