Fire resistive constructions usually specified by the authorities should have quality more than 2nd class of JISA 1302. But in the case of moderate height (less than 45 ft. high) or lower fire resistive occupancy, 3rd class of JISA 1302 becomes the lowest limitations, restricted to the house.
The conclusions drawn from 3rd class fire tests on hollow columns and walls shown in Fig.
1, Fig. 8, are given briefly below.
1. Columns
(1) More than 40 mm thickness around the steel frame will be sufficient when cement mortar is used.
(2) More than 32 mm thickness around the steel frame will attain its purpose when ash aggregate mortar is used.
2.Walls
(1) More than 22 mm thickness in each side of steel frame will be sufficient when Cement mortar is used.
(2) More than 18 mm thickness in each side of steel frame will be sufficient when ash aggregate mortar is used.
(3) Wood fibre cement board will be unsuitable for the base of plaster or cement mortal because of its carbonization.