The IS 1946:1961 standard outlines detailed procedures and specifications for selecting, designing, and installing fixing devices including expansion plugs, shells, and anchors in solid masonry and concrete structures such as walls, ceilings, and floors. This code ensures reliable, durable, and safe attachment of fixtures by addressing material requirements, installation techniques, load capacities, and environmental considerations.
Overview
The IS 1946:1961 standard outlines detailed procedures and specifications for selecting, designing, and installing fixing devices including expansion plugs, shells, and anchors in solid masonry and concrete structures such as walls, ceilings, and floors. This code ensures reliable, durable, and safe attachment of fixtures by addressing material requirements, installation techniques, load capacities, and environmental considerations.
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Frequently Asked
IS 1946 encompasses a range of fixing devices intended for use in solid masonry walls, ceilings, and floors to ensure fixture stability without damaging surface finishes. The primary categories are expansion plugs for screw anchoring, expansion bolts designed for structural load-bearing, and specialized devices engineered to withstand environmental factors such as moisture, chemicals, and temperature variations. This standard promotes clean and durable fixings by specifying precise dimensions and application methods.
According to IS 1946, expansion wall plugs should be constructed from materials like jute fibre, white bronze, or lead alloy depending on the application. For enhanced corrosion resistance, white bronze plugs are paired with cadmium-plated screws, while stainless steel screws are recommended for lead alloy plugs. Brass screws are discouraged for use with white bronze plugs. Additionally, plugs must be termite-resistant and reasonably impervious to moisture to maintain long-term durability.
The selection of fixing device size and length must account for the strength of the masonry substrate. For robust masonry, drill holes matching the device's outer diameter with minimal clearance and maintain standard hole depths sufficient to fully embed the expansion shell and ferrule. In weaker masonry, it is necessary to increase hole depth and use collars to fill excess space, thereby improving anchorage. Plug length should slightly exceed the threaded screw length (by 0 to 2 mm) and be fully embedded within the masonry without protruding into surface finishes.
To achieve secure anchorage without harming masonry, IS 1946 prescribes accurately marking hole centers and drilling holes with diameters closely matching the expansion shell to guarantee a snug lateral press fit. Hole depth should accommodate the shell and ferrule fully, increasing depth and using collars in weak masonry. Insert the shell with or without the bolt depending on type, position the bolt at the hole bottom, apply a steel washer and bolt-anchor cone, then caulk firmly using appropriate tools and techniques. For larger bolts (>12 mm diameter), a second lead cylinder and additional caulking are applied. Finally, place the fixture and tighten nuts to complete anchorage.
IS 1946 mandates that the ultimate direct load capacity of bolt-anchors in standard concrete must be at least equal to the bolt's tensile breaking load. For safe working loads, a factor of safety of 5 is applied for consistent or uniform loads, and 10 for shock or dynamic loads. This translates to safe loads being one-fifth or one-tenth of the ultimate load, respectively. Bolts must be mild steel with standard dimensions, and in weak masonry conditions, deeper holes and multiple anchors are recommended to achieve the desired holding strength.
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