🔩IS 1786:2008IS 456:2000
TMT Steel — Grades & Specifications
IS 1786:2008 governs High Strength Deformed (HSD) steel bars used in reinforced concrete. TMT (Thermo-Mechanically Treated) bars must meet specific yield strength, tensile strength, elongation, and bend test requirements. The "D" suffix (Fe500D, Fe550D) denotes enhanced ductility — critical for earthquake-prone regions like Bengaluru which falls in Seismic Zone II–III.
Grade
Yield (MPa)
Tensile (MPa)
Elongation
Application
Fe415
≥ 415
≥ 485
≥ 14.5%
Compound walls, minor structures
Fe500
≥ 500
≥ 545
≥ 12%
General RCC — basic residential
Fe500D
≥ 500
≥ 565
≥ 16%
Seismic zones — standard residential ✓ Most common
Fe550
≥ 550
≥ 585
≥ 10%
High-rise, heavy load structures
Fe550D
≥ 550
≥ 600
≥ 14.5%
Seismic + high-rise — premium
Fe600
≥ 600
≥ 660
≥ 10%
Industrial, bridges, special structures
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Bend & Rebend Test
All TMT bars must pass a 180° bend test without cracking. Fe500D and above must also pass a rebend test — essential for confirming ductility in seismic applications.
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Chemical Composition
IS 1786 limits Carbon (≤0.30%), Sulphur (≤0.055%), Phosphorus (≤0.055%), and S+P combined (≤0.105%). Higher carbon = stronger but brittle. D-grade has stricter limits.
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Weight Tolerance
Individual bar weight tolerance: ±7% for diameters ≤10mm, ±5% for >10mm. Always verify actual weight at site — underweight bars are a common fraud.
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Corrosion Resistance
For coastal areas or high humidity, specify Fe500D or Fe550D with epoxy coating (IS 13620). Bengaluru inland projects — Fe500D without coating is sufficient.
Homekrate Specification
For all residential projects in Bengaluru, Homekrate specifies Fe500D minimum (Tata Tiscon or JSW Neosteel). For projects above G+2, we upgrade to Fe550D. All steel deliveries are verified against IS 1786 mill test certificates before use.
🏗️IS 269:2015IS 8112:2013IS 456:2000
Cement & Concrete — Grades & Mix Design
IS 269:2015 covers Ordinary Portland Cement (OPC) and IS 8112:2013 covers 43-grade OPC. Concrete mix design is governed by IS 456:2000 (Plain and Reinforced Concrete) and IS 10262:2019 (Mix Proportioning). The minimum grade of concrete for RCC structural elements in residential buildings is M20.
Concrete Grade
fck (N/mm²)
Min Cement (kg/m³)
Application
M15
15
240
Plain concrete, levelling, PCC below footing
M20
20
300
RCC slabs, beams, columns — minimum for residential
M25
25
320
Standard residential RCC — Homekrate standard ✓
M30
30
340
High-rise columns, heavy load beams
M35
35
360
Bridges, industrial, basement walls
M40+
40+
380+
Prestressed concrete, special structures
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Water-Cement Ratio
IS 456 limits w/c ratio to 0.55 for M20, 0.50 for M25, and 0.45 for M30+. Excess water is the #1 cause of weak concrete — do not allow adding water at site.
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Curing Requirements
Minimum curing period: 7 days for OPC, 10 days for blended cements in hot/dry weather. Inadequate curing reduces strength by up to 40%. Homekrate supervises all curing.
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Cover to Reinforcement
Minimum clear cover: 40mm for foundations, 25mm for slabs, 40mm for beams, 40mm for columns. Coastal/exposed — add 10mm. Verified using cover blocks.
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Slump Test (IS 1199)
Workability is tested by slump: 25–75mm for foundations, 50–100mm for beams/columns, 75–100mm for slabs. RMC should arrive within 90 min and target slump.
Homekrate Specification
Homekrate specifies M25 concrete minimum for all structural RCC elements. We use RMC (Ready Mix Concrete) from approved plants with computerised mix design. Cube tests at 7 and 28 days are mandatory on every pour. OPC 53-grade cement (UltraTech or Ambuja) is specified for all structural works.
🧱IS 1077:1992IS 2212:1991IS 4326:2013
Bricks & Masonry — Strength & Specifications
IS 1077:1992 governs Common Burnt Clay Building Bricks. IS 2212:1991 covers brickwork practice. Bricks are classified by compressive strength into Classes 3.5 through 35. For load-bearing masonry, Class 7.5 minimum is required. AAC blocks (IS 2185) are increasingly preferred for their thermal efficiency and light weight.
Class
Comp. Strength
Water Absorption
Use
Class 3.5
3.5 N/mm²
≤ 25%
Non-load bearing partition walls only
Class 5
5.0 N/mm²
≤ 20%
General non-structural masonry
Class 7.5
7.5 N/mm²
≤ 20%
Load-bearing walls, minimum for G+1 ✓
Class 10
10 N/mm²
≤ 15%
Load-bearing walls G+2 and above
AAC Block
3–5 N/mm²
≤ 10%
Non-structural infill — thermal efficient, light
Solid Block
5–7 N/mm²
≤ 10%
Infill + compound walls — Homekrate preferred
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Mortar Mix (IS 2250)
For load-bearing masonry: 1:4 (cement:sand) mortar minimum. Plastering: 1:4 for external, 1:5 for internal. Never use mortar more than 30 minutes after mixing.
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Bond Patterns
IS 2212 requires English bond or Flemish bond for all structural masonry. Stretcher bond is only acceptable for non-load-bearing partition walls.
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Soaking Requirement
Clay bricks must be soaked in water for 12 hours before use to prevent absorption of water from mortar. AAC blocks require only surface wetting — never soaking.
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Dimension Tolerance
Standard modular brick: 190×90×90mm (with mortar: 200×100×100mm). Tolerance: ±3mm on each dimension. Consistent sizing ensures level courses and efficient construction.
Homekrate Specification
Homekrate uses 6-inch solid concrete blocks for external walls and 4-inch AAC blocks for internal partitions. Both exceed IS requirements and deliver better thermal performance than standard clay bricks. All masonry uses 1:4 cement-sand mortar for structural walls.
⚓IS 1904:1986IS 6403:1981IS 2911:2010
Foundation — Design & Soil Requirements
IS 1904:1986 governs design and construction of foundations in soils. IS 6403:1981 covers bearing capacity of shallow foundations. Every structure must have a soil investigation report (IS 1892) before foundation design. In Bengaluru, soil types range from hard rock (excellent bearing) in areas like Jayanagar and Koramangala, to soft expansive soil in peripheral areas requiring deeper foundations.
Foundation Type
Safe Bearing
Depth Min.
Suitable For
Isolated Footing
100–300 kN/m²
1.2–1.5m
Independent columns, G+1 to G+3 on stable soil
Combined Footing
100–200 kN/m²
1.2–1.5m
Adjacent columns with overlapping pressure zones
Strip Footing
75–150 kN/m²
1.0–1.5m
Load-bearing walls, row houses
Raft Foundation
50–100 kN/m²
1.5–2.0m
Soft/expansive soils, G+3 and above ✓ Common in Bengaluru outskirts
Pile Foundation
< 50 kN/m²
8–25m
Very soft soil, waterlogged sites, high-rise
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Soil Investigation (IS 1892)
Mandatory for all structures. Minimum 3 boreholes for residential plots. Must determine: soil type, bearing capacity, water table depth, and presence of expansive clay (black cotton soil).
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Anti-Termite Treatment (IS 6313)
Pre-construction soil treatment mandatory under IS 6313. Applied to soil in foundation trenches, backfill, and plinth area. Prevents structural damage from subterranean termites.
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PCC Below Foundation
M15 Plain Cement Concrete, 100mm thick minimum below all footings as per IS 456. Acts as blinding layer to prevent contamination of structural concrete with soil.
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Foundation Width
Minimum footing width = column width + 150mm on each side. Final sizing by structural engineer based on actual load calculations and soil bearing capacity report.
Homekrate Specification
Homekrate mandates a soil investigation report before every project. We use isolated footings on rock/hard soil and raft foundations on soft or expansive soil. Foundation concrete is always M25 minimum. Anti-termite treatment is included as standard in all our project scopes.
🌍IS 1893:2016IS 13920:2016IS 4326:2013
Earthquake Zones — Seismic Design Requirements
IS 1893:2016 divides India into 4 seismic zones (II to V). Bengaluru falls in Zone II (low intensity) with parts of Karnataka near Zone III. IS 13920:2016 provides ductile detailing requirements for RCC structures in seismic zones. Even in Zone II, good seismic detailing is recommended as it costs little extra and significantly improves structural resilience.
Zone
Intensity (MSK)
Zone Factor (Z)
Key Karnataka Areas
Zone II
VI or less
0.10
Bengaluru, Mysuru, Mangaluru, most of Karnataka
Zone III
VII
0.16
Belgaum, Bidar, parts of north Karnataka
Zone IV
VIII
0.24
Not applicable to Karnataka
Zone V
IX+
0.36
Himalayan belt, Andaman — not applicable
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Ductile Detailing (IS 13920)
Column ties/stirrups must be spaced at d/4 or 6× bar diameter in the confinement zone (top and bottom 600mm of column). Closer spacing = more ductility = better earthquake performance.
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Column-Beam Ratio
Strong column — weak beam principle: column capacity must be 1.2× beam capacity at every joint. Prevents soft-storey collapse which is the most common mode of earthquake failure in RCC buildings.
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Shear Wall Requirement
For G+4 and above in Zone II, shear walls are recommended. In Zone III+, shear walls are mandatory. They resist lateral forces and significantly reduce sway and inter-storey drift.
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Plinth Band & Lintel Band
IS 4326 requires a plinth band (continuous RCC band at plinth level) and lintel band above all openings for masonry structures. These tie the structure and prevent diagonal cracking during earthquakes.
Homekrate Specification
All Homekrate projects are designed to Zone III standards minimum, even though Bengaluru is Zone II. We use Fe500D steel, IS 13920 ductile detailing, plinth and lintel bands, and include a seismic compliance checklist in every project. Better safe than sorry — the cost difference is negligible.
⚡IS 732:2019IS 1239:2004NBC 2016
Electrical & Plumbing — Code Requirements
Electrical installations in buildings are governed by IS 732:2019 (Code of Practice for Electrical Wiring Installations) and the National Building Code (NBC) 2016. Plumbing follows IS 1172:1993 (Basic Requirements for Water Supply) and IS 1239 for GI pipes. BESCOM connections in Bengaluru follow Karnataka Electricity Regulatory Commission (KERC) guidelines.
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Wire Sizing (IS 694)
Minimum wire sizes: Lighting — 1.5 sq mm, Power/fan — 2.5 sq mm, AC — 4 sq mm, Geyser — 4 sq mm, Oven/induction — 6 sq mm. Use ISI-marked FRLS (Flame Retardant Low Smoke) wires only.
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Earthing (IS 3043)
All metallic equipment must be earthed. Plate earthing (GI 600×600×6mm) or pipe earthing at minimum 3m depth. Earth resistance must be ≤ 5 ohms. Separate earth for lightning protection in structures above 15m.
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MCB/ELCB Ratings
ELCB (Earth Leakage Circuit Breaker) is mandatory for all bathroom and external points. Tripping sensitivity: 30mA for life protection. MCB ratings: lighting 6A, power 16A, AC 20A, geyser 20A.
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Conduit Requirements
IS 732 requires all concealed wiring to be in PVC conduit (IS 9537). Minimum conduit size: 20mm for up to 3 wires, 25mm for 4–6 wires. Bends limited to 90° maximum in any run.
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Water Supply (IS 1172)
Minimum water supply: 135 litres per capita per day (lpcd) for residential. Overhead tank capacity: 24-hour storage minimum. Hot and cold supply pipes must have 300mm separation to prevent heat transfer.
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Drainage (IS 1742)
Minimum pipe slopes: soil pipes 1:40, waste pipes 1:20. All traps must have 50mm water seal minimum. IS 1742 requires P-traps for WC and S-traps for floor traps. Rodding access at every 12m.
Homekrate Specification
Homekrate uses ISI-marked FRLS wires (Finolex or Havells), GI conduits for outdoor and PVC for concealed indoor, ELCB on all circuits, and separate circuits for each AC. For plumbing, we use CPVC pipes for hot water and UPVC for cold, with all joints solvent-welded. Complete as-built drawings provided at handover.
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