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IS 4948 : 1994Code of Practice for Glazing in Buildings

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AS 1288 · BS 6262-1 · IBC 2021, Chapter 24
CurrentSpecializedCode of PracticeBIMArchitectural · Doors, Windows and Shutters
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OverviewValues5InternationalTablesFAQ3Related

IS 4948:1994 is the Indian Standard (BIS) for glazing in buildings. This code covers the guidelines for the selection of glass, glazing materials, and the execution of glazing work in buildings. It provides essential design considerations for wind loading on glass panels and specifies the required clearances and setting techniques to prevent stress concentrations and structural failure.

Provides recommendations for the selection and installation of glass and glazing systems in buildings.

Overview

Status
Current
Usage level
Specialized
Domain
Architectural — Doors, Windows and Shutters
Type
Code of Practice
International equivalents
AS 1288:2021 · Standards Australia, AustraliaBS 6262-1:2017 · BSI, United KingdomIBC 2021, Chapter 24 · International Code Council (ICC), USAASTM E1300-16 · ASTM International, USA
Typically used with
IS 2835IS 2553IS 1081IS 419
Also on InfraLens for IS 4948
5Key values2Tables3FAQs

BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.

Practical Notes
! Always provide adequate edge clearance to accommodate the thermal expansion of glass; a lack of clearance is a primary cause of thermal cracking.
! Setting blocks must be made of materials like neoprene or PVC (Shore A hardness 70-90) to properly transfer the weight of the glass to the frame without damaging the edges.
! Glass thickness must be determined not just by aesthetic requirements but strictly by referencing the design wind pressure of the building location and height (IS 875 Part 3).
Frequently referenced clauses
Cl. 3MaterialsCl. 4Design ConsiderationsCl. 5Glazing TechniquesCl. 6Tolerances and Clearances
Pulled from IS 4948:1994. Browse the full clause & table index below in Tables & Referenced Sections.
glassputtysealantstimberaluminumsteelsetting blocks

International Equivalents

Similar International Standards
AS 1288:2021Standards Australia, Australia
HighCurrent
Glass in buildings - Selection and installation
Provides comprehensive guidance on selection and installation for wind loads and human impact, very similar in intent to IS 4948.
BS 6262-1:2017BSI, United Kingdom
HighCurrent
Glazing for buildings - Part 1: General methodology for the selection of glazing
This part is the primary guide for selecting glazing in the UK, covering topics like wind load, safety, and thermal performance, referencing other parts of the standard.
IBC 2021, Chapter 24International Code Council (ICC), USA
MediumCurrent
Glass and Glazing
Defines the mandatory legal requirements for glazing in the US, referencing technical standards like ASTM E1300 for design calculations.
ASTM E1300-16ASTM International, USA
MediumCurrent
Standard Practice for Determining Load Resistance of Glass in Buildings
Focuses specifically on the engineering calculation method for glass strength under wind and other loads, which is a core component of any glazing code.
Key Differences
≠IS 4948:1994 uses wind load calculation methods from the dated IS 875-3:1987, which is a deterministic approach. Modern international standards (e.g., ASTM E1300) use a more sophisticated probabilistic method based on a specified probability of breakage.
≠The criteria for mandatory use of safety glass for human impact in IS 4948 are less detailed and extensive than in modern codes like AS 1288 or the IBC, which have more granular rules for specific locations like stairs, bathrooms, and door sidelites.
≠IS 4948 is a single, concise document. In contrast, the UK equivalent (BS 6262) is a multi-part series, and the US approach uses a building code (IBC) that references multiple specialized ASTM standards, reflecting a higher degree of specialization.
≠International standards have been updated to include detailed guidance on modern glazing systems like point-supported facades, structural sealant glazing (SSG), and advanced coatings, which are not explicitly addressed in the 1994 version of the Indian standard.
Key Similarities
≈All standards are based on the fundamental principles of ensuring glass can safely resist environmental loads (primarily wind) and social loads (human impact).
≈All codes identify similar high-risk locations requiring safety glazing to mitigate human impact risks, such as in doors, low-level windows, and large accessible panels.
≈The requirement to determine design wind pressure based on building height, geographic location, and shape is a universal concept shared by IS 4948 and its international counterparts, even if the calculation methods differ.
≈The standards recognize and provide guidance for the same fundamental glass types, including annealed (float), toughened (fully tempered), heat-strengthened, and laminated glass, acknowledging their different strength and breakage characteristics.
Parameter Comparison
ParameterIS ValueInternationalSource
Basis for Wind Load CalculationDeterministic method based on IS 875 (Part 3) using specified pressure coefficients.Probabilistic method based on a specified probability of breakage (e.g., 8 lites per 1000).ASTM E1300-16
Safety Glazing for 'Low-Level Glazing'Required where the bottom of the glazing is less than 800 mm from the finished floor level.Required where the bottom edge is less than 1000 mm from the floor in non-residential buildings or 500 mm in residential buildings.AS 1288:2021
Safety Glazing in DoorsRequired for all glazing in doors if the bottom is within 800 mm of the floor.Required for all glazing in doors, irrespective of size or height from the floor.AS 1288:2021
Minimum Edge Clearance (Typical for 1-2.5 m² pane)5 mm (from Table 3).Typically 3 mm for metal frames, 5 mm for timber frames.BS 6262-6:2017
Design Stress Concept (Annealed Glass)Implicit in thickness selection charts; no explicit allowable stress is provided for design.No single value; stress is calculated based on load duration, surface condition, and a target probability of breakage.ASTM E1300-16
Consideration of Load DurationImplicitly considered by using wind load (short duration) as the basis, but not explicitly factored for other loads.Glass strength is explicitly de-rated for longer load durations (e.g., snow load vs. 3-second wind gust).AS 1288:2021
⚠ Verify details from original standards before use

Key Values5

Quick Reference Values
Minimum edge clearance for glass area < 0.5 sqm3 mm
Minimum edge cover for glass area < 0.5 sqm5 mm
Minimum front and back clearance2 mm
Minimum length of setting block25 mm
Setting block distance from corners1/4th of pane width (ideal)

Tables & Referenced Sections

Key Tables
Table 1 - Minimum Edge Clearance, Edge Cover and Front/Back Clearance for Glass
Table 2 - Selection of Glass Thickness based on Wind Pressure and Area
Key Clauses
Clause 3 - Materials
Clause 4 - Design Considerations
Clause 5 - Glazing Techniques
Clause 6 - Tolerances and Clearances

Related Resources on InfraLens

Cross-Referenced Codes
IS 2835:2009Flat Transparent Sheet Glass
→
IS 2553:1990Safety Glass - Part 1: General
→
IS 1081:1960Code of practice for fixing and glazing of me...
→
IS 419:2020Leaded Tin Bronze Rods and Bars
→

Frequently Asked Questions3

Why are setting blocks necessary in glazing?+
They support the dead weight of the glass, isolate the glass from the frame to prevent damage, and maintain proper edge clearances for thermal expansion.
How is the thickness of the glass selected?+
Glass thickness is selected based on the surface area of the pane and the maximum design wind pressure it must withstand, using the charts/tables provided in the code.
What is the difference between edge cover and edge clearance?+
Edge cover is the dimension of the glass that is covered by the frame/beading holding it in place, whereas edge clearance is the physical gap between the edge of the glass and the inside of the frame.

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