Masonry walls should be designed to have fire resistance appropriate to their use as detailed in Table 14 which gives notional fire resistances of walls for various types of construction, and for periods from 30 min to 6 h. Other forms of construction may be used, provided evidence of satisfactory performance in use, based on the results of standard fire resistance tests, is produced.
If the required fire resistance of a loadbearing cavity wall with a thickness taken from Table 14 is more than 2 h, the imposed load should be shared by both leaves; otherwise, if the imposed load is carried by the exposed leaf only, the minimum thickness of the exposed leaf should be that given for loadbearing single-leaf walls.
For panel walls which are to provide fire resistance where edge isolation is necessary, special consideration should be given to the edge details.
Where movement joints or edge clearances are required for walls designed to resist fire, they should be filled with a non-combustible material, such as mineral fibre, which still allows the movement joint to function.
Consideration should be given to non-combustible cover strips fixed to both faces of the wall on one side of the joint.
Table 14 ¦ Notional fire resistance of walls
Material Masonry unit type Finisha Minimum thickness of masonryb for notional period of fire resistance
NOTE Non-loadbearing walls are assumed to carry no load other than their own weight and edge restraint. Loadbearing walls may carry any load up to that which produces the maximum permissible design stresses. Interpolation between Table 14(A) and Table 14(B) or between Table 14(C) and Table 14(D) is not permitted.
a The finish should be not less than 13 mm plaster or rendering on each face of a single-leaf wall and on the exposed faces of a cavity wall. SC/SG is sand:cement or sand:gypsum (with or without lime). Plasterboard of an equivalent thickness may be substituted for fire resistance periods up to 2 h. VG is vermiculite:gypsum plaster (1.5:1 to 2:1 by volume). Perlite may be substituted for vermiculite for clay bricks and other materials with similar surfaces.
b The thickness represents either the work size of the unit, or, where applicable for solid walls, the sum of the work sizes of two units together with the work size of the joint between them.
c The minimum thickness given is suitable for 75 mm brick-on-edge construction with a completely solid unit with plane faces.
d The number of cells is that in any cross-section through the wall thickness.
Table 14 ¦ Notional fire resistance of walls (continued)
Material Masonry unit type Finisha Minimum thickness of masonryb for notional period of fire resistance (A) Loadbearing single-leaf walls (continued)
Aggregate
Block Solid None 150 150 140 100 100 90 90
VG 150 100 100 90 90 90 90
Block Solid None or
SC/SG
Block Solid None 215 180 140 100 100 90 90
VG 180 150 100 100 90 90 90
NOTE Non-loadbearing walls are assumed to carry no load other than their own weight and edge restraint. Loadbearing walls may carry any load up to that which produces the maximum permissible design stresses. Interpolation between Table 14(A) and Table 14(B) or between Table 14(C) and Table 14(D) is not permitted.
a The finish should be not less than 13 mm plaster or rendering on each face of a single-leaf wall and on the exposed faces of a cavity wall. SC/SG is sand:cement or sand:gypsum (with or without lime). Plasterboard of an equivalent thickness may be substituted for fire resistance periods up to 2 h. VG is vermiculite:gypsum plaster (1.5:1 to 2:1 by volume). Perlite may be substituted for vermiculite for clay bricks and other materials with similar surfaces.
b The thickness represents either the work size of the unit, or, where applicable for solid walls, the sum of the work sizes of two units together with the work size of the joint between them.
e ) Class 1 aggregates for concrete blocks include limestone, air-cooled blastfurnace slag, foamed or expanded slag, crushed brick, well-burnt clinker, expanded clay or shale, sintered pulverized-fuel ash and pumice. Class 2 aggregates for concrete blocks include all gravels and crushed natural stone, except limestone.
Table 14 ¦ Notional fire resistance of walls (continued)
Material Masonry unit type Finisha Minimum thickness of masonryb for notional period of fire resistance
None 200 200 170 170 100 100 75
VG 170 170 100 100 90 75 75
a The finish should be not less than 13 mm plaster or rendering on each face of a single-leaf wall and on the exposed faces of a cavity wall.
SC/SG is sand:cement or sand:gypsum (with or without lime). Plasterboard of an equivalent thickness may be substituted for fire resistance periods up to 2 h. VG is vermiculite:gypsum plaster (1.5:1 to 2:1 by volume). Perlite may be substituted for vermiculite for clay bricks and other materials with similar surfaces.
b The thickness represents either the work size of the unit, or, where applicable for solid walls, the sum of the work sizes of two units together with the work size of the joint between them.
c The minimum thickness given is suitable for 75 mm brick-on-edge construction with a completely solid unit with plane faces.
e) Class 1 aggregates for concrete blocks include limestone, air-cooled blastfurnace slag, foamed or expanded slag, crushed brick, well-burnt clinker, expanded clay or shale, sintered pulverized-fuel ash and pumice. Class 2 aggregates for concrete blocks include all gravels and crushed natural stone, except limestone.
f) These thicknesses may be reduced to 100 mm for walls built with cellular bricks.
Table 14 ¦ Notional fire resistance of walls (continued)
Material Masonry unit type Finisha Minimum thickness of masonryb for notional period of fire resistance (B) Non-loadbearing single-leaf walls (continued)
Aggregate
None 215 150 140 140 125 125 90
SC/SG 150 140 140 140 125 125 90
VG 150 125 125 100 90 90 75
NOTE Non-loadbearing walls are assumed to carry no load other than their own weight and edge restraint. Loadbearing walls may carry any load up to that which produces the maximum permissible design stresses. Interpolation between Table 14A) and Table 14(B) or between Table 14(C) and Table 14(D) is not permitted.
a The finish should be not less than 13 mm plaster or rendering on each face of a single-leaf wall and on the exposed faces of a cavity wall. SC/SG is sand:cement or sand:gypsum (with or without lime). Plasterboard of an equivalent thickness may be substituted for fire resistance periods up to 2 h. VG is vermiculite:gypsum plaster (1.5:1 to 2:1 by volume). Perlite may be substituted for vermiculite for clay bricks and other materials with similar surfaces.
b The thickness represents either the work size of the unit, or, where applicable for solid walls, the sum of the work sizes of two units together with the work size of the joint between them.
e) Class 1 aggregates for concrete blocks include limestone, air-cooled blastfurnace slag, foamed or expanded slag, crushed brick, well-burnt clinker, expanded clay or shale, sintered pulverized-fuel ash and pumice. Class 2 aggregates for concrete blocks include all gravels and crushed natural stone, except limestone.
Table 14 ¦ Notional fire resistance of walls (continued)
Material Masonry unit type Finisha Minimum thickness of masonryb for notional period of fire resistance
None 1500 150 140 100 100 90 90
NOTE Non-loadbearing walls are assumed to carry no load other than their own weight and edge restraint. Loadbearing walls may carry any load up to that which produces the maximum permissible design stresses. Interpolation between Table 14(A) and Table 14(B) or between Table 14(C) and Table 14(D) is not permitted.
a The finish should be not less than 13 mm plaster or rendering on each face of a single-leaf wall and on the exposed faces of a cavity wall. SC/SG is sand:cement or sand:gypsum (with or without lime). Plasterboard of an equivalent thickness may be substituted for fire resistance periods up to 2 h. VG is vermiculite:gypsum plaster (1.5:1 to 2:1 by volume). Perlite may be substituted for vermiculite for clay bricks and other materials with similar surfaces.
b The thickness represents either the work size of the unit, or, where applicable for solid walls, the sum of the work sizes of two units together with the work size of the joint between them.
d) The number of cells is that in any cross-section through the wall thickness.
e) Class 1 aggregates for concrete blocks include limestone, air-cooled blastfurnace slag, foamed or expanded slag, crushed brick, well-burnt clinker, expanded clay or shale, sintered pulverized-fuel ash and pumice. Class 2 aggregates for concrete blocks include all gravels and crushed natural stone, except limestone.
h)These thicknesses may be reduced to 90 mm if the load is distributed over both leaves.
Table 14 ¦ Notional fire resistance of walls (concluded)
Material Masonry unit type Finisha Minimum thickness of masonryb for notional period of fire resistance (D) Non-load-bearing cavity wallsg)
Clay,
SC/SG 100 100 100 100 100 100 100
Not less
NOTE Non-loadbearing walls are assumed to carry no load other than their own weight and edge restraint. Loadbearing walls may carry any load up to that which produces the maximum permissible design stresses. Interpolation between Table 14(A) and Table 14(B) or between Table 14(C) and Table 14(D) is not permitted.
a The finish should be not less than 13 mm plaster or rendering on each face of a single-leaf wall and on the exposed faces of a cavity wall. SC/SG is sand:cement or sand:gypsum (with or without lime). Plasterboard of an equivalent thickness may be substituted for fire resistance periods up to 2 h. VG is vermiculite:gypsum plaster (1.5:1 to 2:1 by volume). Perlite may be substituted for vermiculite for clay bricks and other materials with similar surfaces.
b The thickness represents either the work size of the unit, or, where applicable for solid walls, the sum of the work sizes of two units together with the work size of the joint between them.
e) Class 1 aggregates for concrete blocks include limestone, air-cooled blastfurnace slag, foamed or expanded slag, crushed brick, well-burnt clinker, expanded clay or shale, sintered pulverized-fuel ash and pumice. Class 2 aggregates for concrete blocks include all gravels and crushed natural stone, except limestone.
g) Thicknesses given here are minimum thicknesses for each leaf in millimetres (mm).
5.9 Thermal performance