| Primary value | 230 mm (load-bearing) (115 partition · 75 filler · 350 mm load-bearing for G+2) |
| Applies to | Burnt-clay brick masonry in cement mortar · Concrete-block and AAC-block masonry (similar thicknesses) · Walls in non-frame and frame-RCC buildings |
| Exceptions | 9-inch (230 mm) — load-bearing walls → G+1 to G+2 max in burnt-clay brick |
| 4.5-inch (115 mm) — internal partitions → Non-load-bearing only | |
| 3-inch (75 mm) — half-brick / partition → Bathroom partitions, store rooms | |
| 13.5-inch (340 mm) — load-bearing G+2+ → Old-style construction or where RCC frame absent | |
| AAC block — equivalent → 200 mm / 150 mm / 100 mm | |
| Measured as | Width of the wall measured perpendicular to its face, including the brick body but not including plaster on either side. Measured at the wall mid-height to avoid local thickening at courses. |
| Source | IS 1905 — Clause 5 (slenderness limits) ✓ Verified |
9 related items across IS codes, knowledge articles, design rules, maps and tools
Wall thickness is set by load + slenderness — a 115 mm partition with 3.5 m height has a slenderness ratio of 30, which IS 1905 caps for non-load-bearing. Use 115 mm walls as load-bearing and the wall buckles laterally under modest gravity load. The 230 / 115 / 75 mm trio covers 99% of Indian residential masonry.
Modern frame-RCC apartments use 230 mm external + 115 mm internal partitions in burnt-clay brick. AAC block at 200 + 150 mm is increasingly common for the lower density and improved insulation. Tier-2 city builders still occasionally use 230 mm load-bearing walls for G+1 dwellings.