How much material is needed for an RCC roof slab?

Multiply the slab area by its thickness for the concrete volume, then split by grade for cement, sand and aggregate. Steel is roughly 80 kg per cubic metre of slab concrete; a 1000 square-foot, 125 mm M20 slab needs about 95 bags of cement and 0.9 tonnes of steel.

What thickness should an RCC roof slab be?

Residential roof slabs are commonly 100 to 150 mm thick (125 mm is typical), depending on span and your structural engineer's design.

How many roofing sheets do I need?

Divide the roof area by the effective area of one sheet (after overlap), then add a little for end laps and cutting. The calculator does this once you enter the sheet size.

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Materials

Roofing Calculator

Two roofs in one tool: an RCC slab mode that gives the concrete (cement, sand, aggregate) and reinforcement steel, and a sheet-roofing mode that gives the number of sheets. Enter the roof area and we do the rest.

All materials Concrete Cement Sand Aggregate Brick Plaster Tile Flooring Paint Roofing Steel

Roof

Roof type

Area measured in

Roof area sq ft

Slab thickness mm

Concrete grade

Steel kg per m³ of slab

Wastage / overlap 10%

Cement required—

Concrete volume—

Sand—

Aggregate—

Reinforcement steel—

Add rates for a cost

Cement ₹/bag

₹

Sand ₹/cft

₹

Aggregate ₹/cft

₹

Steel ₹/kg

₹

How it's calculated

RCC slab: concrete volume is area × thickness; that's scaled by 1.54 and split by the grade ratio into cement, sand and aggregate, and reinforcement is estimated at your kg-per-m³ figure (about 80 kg/m³ is typical for a house slab). Sheets: roof area plus overlap allowance, divided by the area of one sheet.

Steel in a slab varies with span and design — 80 kg/m³ is a planning figure, not a substitute for a bar-bending schedule. Follow your engineer's drawing.

Want only the steel detail? Use the steel weight calculator. Only the concrete? The concrete calculator.

Frequently asked questions

Typical slab thickness?

100–150 mm for houses; 125 mm is common. Your engineer sets it from the span.

How much steel in a slab?

Roughly 80 kg per m³ of slab concrete as a planning figure; the actual comes from the structural design.

What overlap for sheets?

Allow about 10–15% for side and end laps; steeper or windier roofs need more.

Calculated with PropertiesOnline.in — free property & construction calculators · https://propertiesonline.in