Case studies / Shuttering contractor
Formwork Billing Area for a 12-Level Building
A shuttering contractor taking over a part-built building needed the billable area for his labour subcontract, measured to his own rules for heights, shafts and projections.
Institutional building, basement + ground + 10 floors · Thane district, Maharashtra · Client names withheld
Key numbers
- Gross area, 11 slab stages
- 12,972 m²
- Adjusted billable area
- 13,470 m²
- Openings tested
- 141
- Projections classified
- 117
- Deductions applied
- 830 m²
- Weighted projections
- 647 m²
What the client asked
Floor-wise gross, net and adjusted billable built-up area (BUA) from foundation to terrace, using his billing rules: 1.5× for tall storeys, deduct shafts of 2.5 m² or more, no deduction for lifts and stairs, chajjas up to 600 mm at 50%, wider projections and balconies at 100%. Later: deduct the previous contractor's completed work.
Drawings received: 12 drawing files (8 DWG, 4 PDF), a site walk-through video and his written billing rules.
What we did
- Measured 11 slab stages and every opening and projection on each floor, testing each shaft against the 2.5 m² rule one at a time.
- Applied his height multipliers by zone (1.50× and 1.70× on the tall ground floor) and his projection factors.
- Modelled the existing structure from the as-built drawings and the site video to separate the previous contractor's work from his scope.
- Marked every opening and projection on the drawings, so each billed square metre traces to a drawing.
How the numbers were checked
- At least three printed dimensions checked on each measured plan, and each non-typical level measured on its own.
- Two workbooks with 2,355 formulas and no formula errors; the 2.49 / 2.50 m² shaft threshold tested both ways.
- 156 frames of the site video reviewed to tell built from unbuilt work.
What we found in the drawings
- The function hall is 4.26 m tall on its plan but shown at the ordinary 3.64 m rise in the section. We raised it and the client chose the multiplier.
- Lift shafts are printed at one size and drawn at another on two floors.
- Basement and ground levels differ between the latest architecture and the foundation drawings.
What the client received
- BUA measurement workbook (Excel) with floor-wise gross, net and adjusted areas.
- Component completion workbook separating the previous contractor's work.
- Review PDF with marked drawings for every opening and projection.
The full measurement went out the same day as the enquiry; the revision with his new rules followed the next morning.
Delivered and paid. The previous-contractor deduction is a conditional estimate and the final billable area is still to be agreed, so 13,470 m² is the adjusted area before that deduction, not the final bill.