The 1964 edition of this code offers detailed instructions for designing and building stone slab floors or roofs supported by joists, including the use of lime or cement concrete layers for insulation and waterproofing. It is vital for professionals working with natural stones like granite, sandstone, and limestone, especially in areas where these materials are prevalent. The code addresses structural design, material criteria, handling, installation methods, and finishing techniques to achieve durable and stable stone slab flooring systems.
Overview
The 1964 edition of this code offers detailed instructions for designing and building stone slab floors or roofs supported by joists, including the use of lime or cement concrete layers for insulation and waterproofing. It is vital for professionals working with natural stones like granite, sandstone, and limestone, especially in areas where these materials are prevalent. The code addresses structural design, material criteria, handling, installation methods, and finishing techniques to achieve durable and stable stone slab flooring systems.
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Contents
Structure
Frequently Asked
According to the 1964 code, suitable natural stones for slab flooring must be hard, durable, and free from defects such as decay, cracks, or sand holes. They should have a water absorption rate not exceeding 5%, and a minimum transverse strength of 55 kg/cm² as standardized in IS 1121-1957. Stones like granite, basalt, quartzite, dense sandstone, and hard marble varieties are recommended. Proper seasoning and dressing of newly quarried stones also enhance their suitability.
Joists should be spaced between 30 cm and 80 cm to adequately support the stone slabs. The bearing width of joists for slabs must be at least 25 mm but not exceed half the width of the joist. Slabs may be placed on top or over the bottom flange of steel joists with appropriate waterproofing. Joists are designed as beams carrying combined dead and live loads per IS 875-1964, using relevant design codes for RCC (IS 456-1964, IS 1343-1960), steel (IS 800-1962), and timber beams (IS 883-1961). Ends should be embedded securely in masonry or concrete to provide a stable support.
For waterproofing and durability, lime concrete mixes of 1:1:2 (lime:sand:aggregate) are recommended for exposed areas like roofs, while a 1:1:3 ratio is suitable where exposure is less or additional waterproofing exists. The minimum consolidated thickness of the lime concrete layer should be 7.5 cm. Cement concrete layers should comply with IS 456 requirements, with thickness ensuring durability and level surfaces. Prior to concrete placement, stone slabs are grouted with a stiff 1:3 cement-sand mortar, optionally enhanced with 5% crude oil by cement weight for improved sealing.
Waterproofing is achieved by applying a lime or cement concrete layer over the stone slabs, which also provides insulation. A minimum slope of 1:48 is required on the concrete or joists to ensure proper drainage. Joints between stone slabs are filled with stiff cement-sand mortar (1:3 mix), which may include 5% crude oil by cement weight to improve water resistance. Additionally, gaps between joists are filled with masonry or concrete to create a level base and prevent water accumulation.
Finishing layers typically involve a 20 mm thick cement plaster with a 1:3 mix ratio. Alternative finishes permitted include cement tiles (per IS 1443-1959), terrazzo flooring (IS 2114-1962), mud PHUSKA roof finish (IS 2115-1962), and mastic asphalt flooring (IS 1196-1958). These finishes provide durability, protection, and aesthetic enhancement. It is essential that supporting structures are fully completed and leveled prior to applying finishes, and that installation follows the respective Indian Standard codes.
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