Kumar IronStart with the right expectation
The exact steel in a building comes from the structural drawings and the bar bending schedule (BBS). Nothing replaces that. But owners and contractors need a number much earlier, to budget, to compare quotes, and to book steel when the rate is good. Thumb rules give you that early number, usually within 10 to 15 percent of the final quantity.
Steel quantity depends on the number of floors, column spacing, span of rooms, soil, seismic zone and the grade of steel. Treat the figures below as a planning range, not a design.
Thumb rule by built-up area
For a normal RCC framed house in north India, steel works out to roughly the following per square foot of built-up area (all floors added together):
| Type of building | Steel (kg per sq ft) |
|---|---|
| Ground floor only, load bearing walls with RCC roof | 2.0 to 2.5 |
| Ground floor framed structure (columns and beams) | 3.0 to 3.5 |
| G+1 or G+2 framed house | 3.5 to 4.5 |
| G+3 and above, or seismic zone IV detailing | 4.5 to 5.5 |
Houses in seismic zone IV, which includes much of west UP, sit at the higher end because ductile detailing needs closer stirrups and more confinement steel in columns and beam ends.
Thumb rule by element
If you already know the concrete quantity of each element, steel per cubic metre of concrete is more accurate:
| Element | Steel (kg per m³ of concrete) | Typical bar sizes |
|---|---|---|
| Footings | 70 to 100 | 10 mm, 12 mm |
| Plinth and tie beams | 110 to 140 | 10 mm, 12 mm, 8 mm stirrups |
| Columns | 160 to 250 | 12 mm, 16 mm, 8 mm ties |
| Beams | 120 to 180 | 12 mm, 16 mm, 8 mm stirrups |
| Slabs | 70 to 100 | 8 mm, 10 mm |
| Staircase | 80 to 110 | 10 mm, 12 mm |
| Lintels and sunshades | 60 to 90 | 8 mm, 10 mm |
Worked example: 1000 sq ft G+1 house
Say you are building a framed house with 1000 sq ft on the ground floor and 1000 sq ft on the first floor, in a zone IV area. Total built-up area is 2000 sq ft. Using 4.0 kg per sq ft from the table:
2000 sq ft × 4.0 kg = 8000 kg, or about 8 tonnes of TMT steel.
A typical split across elements and bar sizes for a house like this looks like:
| Element | Share | Approx. steel |
|---|---|---|
| Footings and plinth beams | 15% | 1200 kg |
| Columns | 25% | 2000 kg |
| Beams | 25% | 2000 kg |
| Slabs (two floors) | 25% | 2000 kg |
| Staircase, lintels, sunshades | 10% | 800 kg |
By size, this usually comes to roughly 30% in 8 mm (stirrups, ties, slab bars), 20% in 10 mm, 30% in 12 mm and 20% in 16 mm. Your drawings may differ, especially if columns use 20 mm bars.
Add 3 to 5 percent for wastage in cutting, laps and offcuts. In this example, order around 8.3 to 8.4 tonnes in total, in two or three lots as work progresses.
Turning kilos into bars
Steel is billed by weight but used by length. TMT bars come in 12 m lengths. Weight per metre is D² ÷ 162, where D is the diameter in mm. So a 12 m bar of 12 mm weighs about 10.67 kg, and one tonne of 12 mm is about 93 bars. Our TMT bar weight chart lists every size, and the steel calculator does this conversion for you.
Ways to avoid over or under ordering
- Get a bar bending schedule from your engineer as soon as drawings are ready. It gives the exact cut lengths and weight per size.
- Order footing and column steel first, then slab steel closer to the slab date. Steel kept on open ground for months rusts.
- Stick to the grade on the drawing, usually Fe500D in this region.
- Count bundles and weigh on delivery. Billing should be by actual weight.
- Keep 8 mm and 10 mm slightly extra. Stirrups and slab bars run short more often than main bars.
Frequently asked questions
- How much steel is needed for a 1000 sq ft house?
- For a single-storey framed house of 1000 sq ft, plan on about 3 to 3.5 tonnes. For 1000 sq ft on each of two floors (2000 sq ft total), plan on about 7.5 to 9 tonnes. Your bar bending schedule gives the exact figure.
- What is the thumb rule for steel per sq ft?
- For a G+1 or G+2 RCC framed house, about 3.5 to 4.5 kg per sq ft of built-up area. Load bearing single-storey houses use less, around 2 to 2.5 kg per sq ft.
- Which bar sizes are used most in a house?
- 8 mm for stirrups, ties and slabs, 10 mm for slabs and light beams, and 12 mm and 16 mm for columns, beams and footings. Bigger columns may use 20 mm.
- How much extra steel should I order for wastage?
- Around 3 to 5 percent over the bar bending schedule covers cutting, laps and offcuts. More than that usually points to poor cutting planning on site.