Sri Lanka House Construction Material Calculator

The calculator walks the same six-stage take-off a Sri Lankan quantity surveyor builds when preparing a BOQ for a residential house: geometry → masonry → plaster → concrete → reinforcement → finishes. Every per-square-metre coefficient below traces back to a published CIDA or ICTAD clause, and each line in the BOQ summary cites the source it came from.

1. Geometry from floor area

Floor area in square feet is converted to square metres (1 m² = 10.764 sqft). A 1:1.4 rectangular footprint is assumed — this is the ICTAD-residential central value for single-family Sri Lankan houses — and the external perimeter is derived as P = 2 × (1 + 1.4) × √(footprint / 1.4). Wall area is the perimeter × storey height (2.7 m) × number of storeys, with a 22 % deduction for doors and windows. From the second storey onwards the tool adds 18 % to the perimeter to cover interior partitions and stair-well walls.

2. Masonry — bricks and mortar

A 9-inch brick wall in 1:5 cement mortar uses 130 bricks, 0.36 bags of cement and 2 ft³ of sand per m² of finished wall (ICTAD MMBW Table 3-A). A 4.5-inch partition is half of those numbers. Six-inch hollow cement blocks (400 × 200 × 150 mm, SLS 1397) come in at 12.5 blocks per m² with a leaner 1:6 mortar.

3. Plaster — both faces

12 mm 1:5 plaster on a single face consumes 0.18 bags of cement and 0.36 ft³ of sand per m² of wall (CIDA SCA/8 §4). The calculator doubles those numbers to 0.36 bags + 0.72 ft³ per m² when you tick “plaster both faces”. Internal-only plastering (one face) is rare in Sri Lankan residential practice because exposed brick weathers poorly in the monsoon, so this is on by default.

4. Concrete — foundation and above-grade RCC

Foundation volume = perimeter × trench width × depth × 1.5 (the 1.5 multiplier accounts for over-excavation and back-fill). Of that trench volume, 25 % is 1:3:6 reinforced concrete footing — 4.2 bags, 16.3 ft³ sand and 32.6 ft³ metal per m³ — and 75 % is rubble masonry packing. Trench width steps up with storey count: 0.45 m for a bungalow, 0.60 m for two storeys, 0.75 m for three.

Above-grade structural RCC (1:2:4) covers lintels, ring beams, columns and the slab where applicable. The volume per m² of total floor area is 0.03 m³/m² for a tile roof (just lintels, columns and the ground beam), 0.072 m³/m² for a full RCC slab roof (slab + supporting beams + columns), and 0.022 m³/m² for a lighter asbestos sheet roof. A 1:2:4 cubic metre needs 6.4 bags + 14 ft³ sand + 28 ft³ metal.

5. Reinforcement steel

ICTAD's residential benchmark is 60 kg/m³ in the foundation footing and 90 kg/m³blended for the above-grade RCC (a weighted average of 100 kg/m³ for beams, 110 kg/m³ for columns and 80 kg/m³ for slabs, which is what a typical residential design comes out to). The mix of TMT bar diameters is set by the structural engineer's drawings, so this tool reports a single kilogram total rather than guessing a Y10 / Y12 / Y16 split.

6. Roof finish

A calicut clay tile roof needs 14 tiles per m² of roof area and 0.045 m³ of timber per m² for rafters, battens and the ridge piece (CIDA RCS 4.2). The roof itself is 15 % larger than the floor footprint because of pitch and overhang, so a 1,000 sqft house has about 107 m² of roof and ≈ 1,500 tiles before wastage. An asbestos sheet roof uses 0.95 sheets per m² of roof area; an RCC slab roof is already captured in the above-grade concrete line.

Cross-check against the published rule-of-thumb

The detailed estimate is reconciled against the CIDA contractor briefing band of 0.40–0.55 bags per sqft for single-storey houses, 0.50–0.65 for two-storey and 0.60–0.75 for three-storey. When the two methods agree (which they should for any reasonable input), the calculator shows a green “cross-checked” tick. When they disagree, the result is flagged as outside the published band so you can investigate the geometry assumptions before trusting the number.

What the calculator does not include

Labour, transport, scaffolding, plumbing, electrical, painting, tiling, joinery, fittings, boundary walls, gates, parking, driveways, septic tanks, water tanks, statutory approvals, professional fees and the cost of land. The scope is the structural shell — foundation, walls, plaster, RCC, roof finish — because those are the lines a contractor's BOQ inflates first and the ones you can sanity-check with published per-unit rates. For municipal approval fees use the building approval fee calculator.

Three scenarios that map to common Sri Lankan residential builds. Each was computed by the calculator itself, so the numbers on this page always match the output you'll see when you enter the same inputs above.

• CIDA — Construction Industry Development Authority of Sri Lanka (Specifications for Building Works, SCA/8)
• CIDA — Method of Measurement of Building Works (ICTAD/DEV/MMBW)
• Sri Lanka Standards Institution — SLS 107 (OPC), SLS 855 (bricks), SLS 1397 (cement blocks)

Per-unit material rates on this page were last cross-checked against the CIDA and ICTAD sources on 2026-05-17. Market rates for the indicative cost band are reviewed quarterly.