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IS 2691:1988 is the Indian Standard (BIS) for burnt clay facing bricks-specification. This standard specifies the dimensions, physical requirements, and quality standards for burnt clay facing bricks intended for use in masonry walls and facades where no plastering is applied.
burnt clay facing bricks-Specification
Overview
Status
Current
Usage level
Specialized
Domain
Materials Science — Clay and Stabilized Soil Products
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Since facing bricks remain unplastered, visual inspection for uniform color, sharp edges, and absence of cracks or chips is just as critical as strength testing.
! Strict efflorescence testing is required because salt deposits will permanently degrade the aesthetic value of the exposed facade.
! Ensure proper handling and stacking at the site to prevent damage to the clean edges of facing bricks.
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
burnt clayfacing bricksmasonryceramics
International Equivalents
Similar International Standards
ASTM C216-23ASTM International, USA
HighCurrent
Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale)
Defines specifications for bricks used in exposed masonry applications, covering aesthetics and durability.
BS EN 771-1:2011+A1:2015BSI / CEN, UK / Europe
HighCurrent
Specification for masonry units - Part 1: Clay masonry units
Harmonized European standard for all clay masonry units, including those for facing applications.
AS/NZS 4455.1:2008Standards Australia / Standards New Zealand, Australia / New Zealand
MediumCurrent
Masonry units and segmental pavers and flags - Part 1: Masonry units
Covers all masonry units, with specific requirements for facing units based on appearance and salt attack resistance.
Key Differences
≠IS 2691 uses a prescriptive classification system based on compressive strength (Class I, II), whereas BS EN 771-1 is a performance-based standard where manufacturers declare properties without fixed classes.
≠The minimum compressive strength required by IS 2691 (7.0 N/mm²) is significantly lower than the minimums specified in ASTM C216 (17.2 N/mm² for Grade MW).
≠Water absorption testing methods differ significantly. IS 2691 specifies a 24-hour cold water immersion test, while ASTM C216 uses a more aggressive 5-hour boiling test, leading to non-comparable results.
≠ASTM C216 classifies bricks by weathering resistance (Severe Weathering, Moderate Weathering), a concept not explicitly quantified in the same way in IS 2691, which relies on strength and absorption limits.
Key Similarities
≈All standards have the core purpose of specifying requirements for burnt clay bricks intended for use in visually exposed masonry.
≈All standards specify and set limits for key physical properties including compressive strength, water absorption, and dimensional tolerances.
≈Each standard includes provisions to control or evaluate efflorescence to ensure the aesthetic quality of the finished masonry, although test methods and criteria vary.
≈All standards define permissible deviations from specified dimensions (length, width, height) to ensure uniformity and workability during construction.
Parameter Comparison
Parameter
IS Value
International
Source
Classification Basis
Compressive Strength (Class I, II)
Weathering Resistance (SW, MW) and Appearance (FBX, FBS, FBA)
ASTM C216-23
Minimum Compressive Strength
Class II: ≥ 7.0 N/mm²
Grade MW: ≥ 17.2 N/mm² (2500 psi)
ASTM C216-23
Maximum Water Absorption
≤ 15% (24-hr cold soak)
Average ≤ 17.0% (5-hr boil) for Grade SW
ASTM C216-23
Efflorescence Requirement
Rating of 'Slight' or 'Moderate' in visual test
Manufacturer declares Active Soluble Salts category (e.g., S2 for low)
BS EN 771-1:2011+A1:2015
Dimensional Tolerance (on 190-200mm length)
± 3 mm
Tolerance Category T2: ±4 mm (on declared work size)