Estimating and Costing
What this domain tests
Estimating and Costing tests quantity take-off, bill of quantities, rate build-up and tender totals. You must measure pipe, fittings, fixtures and labour in the correct units, then add wastage, overheads and taxes.
Core rules
- Measure pipe in running metres, fittings in numbers, fixtures in numbers, and excavation/backfill in cubic metres.
- Take off from drawings and schedules; record location and size so quantities can be checked.
- Add wastage for cuts and damage: often 5–10% for pipe, but use the project allowance.
- A rate build-up includes material, labour, tools/plant, overheads and profit; tax is added as required.
- Separate lead, lift and height allowances if the work is above normal reach.
- A BOQ is a priced schedule; a tender total is the sum of measured items plus provisional sums and taxes.
Worked example
25 m of 25 mm CPVC pipe at ₹180/m costs ₹4,500. Add 5% wastage: 25 × 0.05 = 1.25 m, or ₹225, giving ₹4,725. Add 18% GST: ₹4,725 × 0.18 = ₹850.50, total ₹5,575.50. The reasoning is material cost first, then wastage on quantity, then tax on the extended amount; labour and fittings are separate items.
Traps
Mixing metres and numbers, forgetting fittings and supports, applying GST before wastage, ignoring height/lead, and pricing a provisional sum as a measured item are common mistakes.