IS 1905:2019 is the Indian Standard (BIS) for structural design of masonry buildings. This code provides guidelines for the structural design of unreinforced masonry buildings. It covers materials like bricks and mortar, design principles using the allowable stress method, and specific requirements for stability, walls, and columns, including crucial provisions for earthquake-resistant design in different seismic zones.
Specifies design and construction requirements for load-bearing and non-load-bearing masonry walls and buildings.
Key design parameters including slenderness ratios, permissible stresses, material properties, and effective dimension coefficients for masonry structures.
| Reference | Value | Clause |
|---|---|---|
| Max Slenderness Ratio (Wall)— For walls up to two storeys. | 27 | Cl. 6.2.1 |
| Max Slenderness Ratio (Column)— A column is an isolated vertical load-bearing member with h/t > 4. | 12 | Cl. 6.2.2 |
| Max Eccentricity of Vertical Load— Where 't' is the thickness of the member. | t/6 | Cl. 6.3.1 |
| Min Thickness (Load-bearing, ≤2 storeys)— For buildings with G+1 or G+2 floors. | 190 mm | Cl. 4.2.1 |
| Min Thickness (Load-bearing, >2 storeys)— For buildings with more than two storeys. | 230 mm | Cl. 4.2.1 |
| Effective Height (Restrained Top & Bottom)— For walls effectively restrained in position and direction at both ends. | 0.75 H | Cl. 6.4.2.1 (Table 6) |
| Effective Height (Cantilever Wall)— For walls effectively restrained at bottom, but not at top. | 2.0 H | Cl. 6.4.2.1 (Table 6) |
| Effective Length (Wall with Cross Walls)— For a continuous wall with cross walls at both ends. | 0.8 L | Cl. 6.4.3.1 (Table 7) |
| Basic Compressive Stress (10MPa Brick, M1 Mortar)— For solid bricks with crushing strength of 10 N/mm². | 0.96 N/mm² | Cl. 7.1 (Table 8) |
| Basic Compressive Stress (5MPa Brick, H1 Mortar)— For solid bricks with crushing strength of 5 N/mm². | 0.53 N/mm² | Cl. 7.1 (Table 8) |
| Stress Reduction Factor (SR = 20)— For slenderness ratio of 20. | 0.61 | Cl. 7.1.1.1 (Table 9) |
| Stress Reduction Factor (SR = 27)— For max slenderness ratio of 27. | 0.39 | Cl. 7.1.1.1 (Table 9) |
| Area Reduction Factor (Small Piers)— For piers with cross-sectional area (A) ≤ 0.2 m². | 0.7 + 1.5A | Cl. 7.1.1.3 |
| Shape Modification Factor (h/t ≤ 0.75)— For solid units with height/thickness ratio ≤ 0.75. | 1.0 | Cl. 7.1.2 (Table 10) |
| Permissible Bending Tension (Normal to bed, M1)— For M1 grade mortar. | 0.07 N/mm² | Cl. 7.2.1.1 (Table 11) |
| Permissible Bending Tension (Parallel to bed, M1)— For M1 grade mortar. | 0.14 N/mm² | Cl. 7.2.1.2 (Table 11) |
| Permissible Shear Stress (Formula)— Where f_d is compressive stress due to dead loads. | 0.1 + f_d/6 (N/mm²) | Cl. 7.3.1 |
| Max Permissible Shear Stress— Upper limit for permissible shear stress. | 0.5 N/mm² | Cl. 7.3.1 |
| Min Brick Compressive Strength— For common burnt clay bricks used in masonry. | 3.5 N/mm² | Cl. 3.1.1 |
| Max Brick Water Absorption— For common burnt clay bricks after 24h immersion in cold water. | 20 % by weight | Cl. 3.1.1 (ref. IS 1077) |
| Mortar Mix Proportion (M1)— By volume. | 1:3 (Cement:Sand) | Cl. 3.4.2 (Table 3) |
| Min Mortar Strength (M1, 28-day)— Minimum compressive strength for M1 grade mortar. | 10 N/mm² | Cl. 3.4.2 (Table 4) |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
IS 1905 (2019) is the Code of Practice for Structural Design of Masonry Buildings — the IS standard for designing load-bearing masonry buildings (brick, concrete block, stone masonry). With significant low-rise residential + institutional construction using masonry, this code is fundamental for Indian builders + structural engineers.
Use IS 1905 when you are: - Designing load-bearing masonry residential buildings (1-4 storey) - Specifying structural masonry for low-rise institutional / commercial buildings - Doing strength + stability design of masonry walls - Specifying reinforced masonry for seismic zones - Designing masonry under combined load (gravity + lateral) - Cross-referencing with IS 456:2000 (RCC bands + lintels) + IS 4326 (earthquake-resistant masonry)
What IS 1905 covers: - Material specifications (brick, block, mortar) - Allowable stresses - Design loads + load combinations - Wall design (axial, bending, lateral) - Combined load analysis - Reinforced masonry - Seismic considerations - Foundation requirements - Joints + bonding - Construction quality
Masonry materials: - Bricks: common burnt clay (per IS 1077); concrete (per IS 2185) - Blocks: concrete (per IS 2185); fly ash (per IS 12894) - Stone: dressed (kotah, marble); coursed rubble - Mortar: cement-sand (1:4 to 1:6); cement-lime-sand (mixed)
Brick grades (per IS 1077): - Grade A: minimum compressive strength 10 MPa (well-burnt; first class) - Grade B: 7.5 MPa (well-burnt; second class) - Grade C: 5 MPa (lower quality; not for structural)
Wall design types: - Plain masonry: unreinforced; for gravity loads - Reinforced masonry: steel bars in vertical / horizontal joints; for lateral loads - Confined masonry: RCC bands at sill, lintel, roof; modern practice
Design loads: - Dead loads (per IS 875 Part 1) - Live loads (per IS 875 Part 2:1987) - Wind loads (per IS 875 Part 3) - Earthquake (per IS 1893 + IS 4326)
Allowable stresses (per IS 1905): - Brick masonry (Grade A): 0.5-1.0 MPa (depending on mortar) - Concrete block (M20): 1.0-1.5 MPa - Stone masonry: higher; typically 2-5 MPa - Bond strength (mortar-brick): ≥ 0.1 MPa typical
Wall thickness: - Load-bearing (single storey): 230 mm typical - Load-bearing (multi-storey): 350-450 mm - Partition (non-bearing): 115 mm - External wall (cavity for insulation): 350+ mm
Eccentricity + slenderness: - Wall slenderness (height/thickness ratio): ≤ 18 typical - Reduced for slender walls - Buckling check mandatory - Effective length per support conditions
Allowable compressive stress (vertical load): - Single brick wall (230 mm): 0.5-0.8 MPa - Double brick wall (350 mm): 0.8-1.2 MPa - Concrete block (200 mm): 1.0-1.5 MPa - Stone masonry: 2.5-5.0 MPa (depending on stone + mortar)
Allowable bending + shear: - Bending: 0.1-0.5 MPa (perpendicular to bed joint) - Shear: 0.3-0.5 MPa - Eccentric loading: stress + bending consideration
Wall design (axial load): - Allowable load = allowable stress × cross-sectional area × slenderness factor - Slenderness factor: 1.0 for short walls; 0.5-0.7 for slender
Seismic design (per IS 4326): - Bond beam at every floor + roof level - Vertical reinforcement at corners + jamb openings - Concrete blocks (CC) in mortar for seismic improvement - Anchorage of beams + slabs to walls
Confined masonry (modern practice): - RCC bands: at sill, lintel, gable, plinth - Vertical RCC columns at corners + openings - Improves seismic + lateral resistance - Tying + integrity for masonry building
Construction quality requirements: - Mortar mix: 1:6 typical for second class; 1:4 for first class - Mortar consistency: workable; not too dry - Brick wetting: soaked before laying (15-30 min) - Bond pattern: stretcher / header for full bonding - Joint thickness: 10-12 mm typical - Joint filling: complete; no voids - Curing: essential; sprinkle water for 7+ days
Bond patterns: - English bond: alternating stretcher + header courses; strongest - Flemish bond: stretcher + header in same course; less common - Stretcher bond: simple; weak in transverse - Bonded for full strength
Foundations: - Mat or strip footing for masonry walls - Width: wall thickness + safety margin - Depth: below frost line + per soil bearing - PCC layer: 75-100 mm before stonework / brickwork - DPC (Damp-Proof Course): at plinth level mandatory
Maintenance + service: - Periodic re-pointing: mortar joint maintenance every 25-50 years - Crack repair: structural / non-structural assessment - Re-painting / surface treatment - Service life: 50-100+ years for well-built masonry
1. Wrong brick grade for application. Grade C in load-bearing; failure. Grade A or B for structural. 2. Mortar mix incorrect. Too lean; bond weak. 1:4 to 1:6 cement-sand for load-bearing. 3. Mortar joint thickness inconsistent. Bond weak; cracking. 10-12 mm uniform. 4. No curing. Mortar dry-cures; bond inadequate. 7+ days water curing. 5. No seismic bands. Masonry in earthquake zones; collapse. RCC bands per IS 4326. 6. Vertical reinforcement at corners missing. Building corners + openings vulnerable. Per IS 4326. 7. Eccentric load on wall. Stress increased; buckling risk. Eccentricity check. 8. Slenderness > 18. Buckling risk. Design check + reinforcement. 9. DPC missing at plinth. Moisture rising; mortar deterioration. Mandatory DPC. 10. Brick wetting inadequate. Mortar dries too fast; bond weak. Soak bricks before laying. 11. No bond pattern. Stretcher bond only; weak transverse. English bond preferred. 12. Cracking ignored. Settlement / overstress; not repaired. Assess + repair. 13. No foundation design. Wall on inadequate foundation; differential settlement. Per IS 1080 + IS 6403. 14. Wall thickness inadequate. Slenderness + load capacity issues. Per design. 15. Pre-stressed masonry not considered. Where applicable; advanced design. Per code. 16. Aesthetic vs structural. Decorative masonry not structurally designed. Identify structural vs non-structural. 17. Damp-proof course poor. Moisture migration; mortar erosion. Quality DPC.
Masonry building project — IS 1905 touchpoints:
1. Design phase: - Architectural design coordination - Structural design per IS 1905 + IS 4326 - Material specifications - Drawings + details
2. Procurement: - Bricks / blocks per IS 1077 / IS 2185 - Mortar materials - Steel for RCC bands + columns
3. Foundation: - Per soil bearing - DPC at plinth - Plinth band casting
4. Masonry construction: - Brick wetting + mortar mixing - Layer-by-layer per design - Bond pattern verified - Joint thickness consistent - Curing throughout
5. Reinforced masonry: - Vertical reinforcement at corners + openings - Horizontal reinforcement in mortar joints - RCC bands at sill / lintel / roof - Per IS 4326 seismic design
6. Quality control: - Material testing - Construction inspection - Compressive strength of masonry units - Mortar quality
7. Operations + maintenance: - Annual visual inspection - Periodic re-pointing (every 25-50 years) - Crack assessment + repair - 50-100+ year service life
IS 1905 is the fundamental design code for India's masonry construction — applied on every residential building, every institutional structure, every low-rise commercial building using load-bearing masonry.