A take-off that under-prices the job: measurements, specification and wastage
You are quoting for the plumbing of a two-storey school toilet block with 8 WC pans, 6 wash basins and 4 urinals. Your junior measures the 15 mm branch pipe as 42 m, the 20 mm as 26 m and the 25 mm as 18 m, and prices all 42 m of 15 mm as CPVC at Rs 240 per metre. He adds 3% wastage, 18% labour on material and 18% GST. Reviewing the drawing you notice that: the block is two storeys with three risers, each 3.2 m per floor, and the risers appear nowhere in his sheet; the vertical drops to the six basins, about 8 m in all, are also missing; only two basins in the staff room have a hot water connection; and the spoil-heap quotation he used for fittings assumes a 5% wastage on fittings while the site's past jobs have run at 8%. The client wants the lowest bid and the head teacher wants the quote the same week.
1. Identify which of the omissions and assumptions matter most, and state in which direction each one moves the quote.
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The errors are not equal in size, and the direction matters more than the amount:
- Missing risers (largest under-pricing). Three risers at 3.2 m per floor over two floors is 3 x 2 x 3.2 = 19.2 m of 25 mm pipe, plus elbows, clamps and supports. This is a straight omission and it moves the quote down by the full cost of that pipe and its fittings and labour.
- Missing basin drops. About 8 m of 15 mm pipe plus 6 pairs of angle valves and connectors. Again the quote moves down, but by less.
- CPVC priced for the whole 15 mm run. This moves the quote up very sharply, because CPVC at Rs 240/m is roughly three times UPVC at Rs 85/m. Only the staff-room hot branch needs CPVC; the cold branches to basins, WCs and urinals do not.
- 3% versus 8% wastage on fittings. Moves the quote down and is a real risk on a small job, because elbows, tees and couplings for 15 to 25 mm lines get cut and broken in handling.
- Labour as a flat 18% of material. This is a risk rather than an omission: because the junior over-priced the CPVC, the labour figure is inflated on paper; once the specification is corrected, 18% of a smaller material figure will not cover the actual fixing time.
The net effect of the first two omissions and the over-specification can be a quote that looks competitive, wins the job, and then loses money at the fittings stage.
2. Recompute the 15 mm and 25 mm quantities and show the saving from correcting the CPVC specification.
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Quantities
- 15 mm: measured 42 m + basin drops 8 m = 50 m. Add wastage at 5% (a fair figure for small-bore pipe with many bends): 50 x 1.05 = 52.5 m, and 8% on fittings.
- 25 mm: measured 18 m + risers 3 x 2 x 3.2 = 19.2 m = 37.2 m. At 5% wastage: 37.2 x 1.05 = 39.1 m.
- The 20 mm quantity stays at 26 m but should also be checked against the drawing for the urinal range, which is often run in 20 mm.
Specification saving on the 15 mm line
- Junior's basis: 42 m x Rs 240 = Rs 10,080.
- Corrected basis: hot branch to the two staff basins, say 10 m of CPVC at Rs 240 = Rs 2,400; remaining 40 m in UPVC at Rs 85 = Rs 3,400; total Rs 5,800.
- Saving before wastage, labour and GST: 10,080 - 5,800 = Rs 4,280 on this one item.
The saving is not a reason to under-quote; it is a reason to spend the money where it belongs - on the risers and the correct wastage - instead of on CPVC in cold-water branches where it adds nothing.
3. The client insists on the lowest bid and the head teacher wants the quote this week. What do you submit, and how do you present the corrected figures without losing the job?
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I would submit a corrected quote with the specification clearly stated, not the junior's sheet.
- Write the specification into the quote: CPVC for the hot branch to the two staff-room basins only; UPVC for the remaining cold branches; GI or as drawn for the risers. A quote without a specification is what allows the next contractor to undercut on paper and then substitute material on site.
- Show the quantities as measured, with risers and drops listed separately so the head teacher can see what is being paid for. A short measurement sheet attached to the quote is the best defence against a later argument about extras.
- Keep wastage and labour realistic (about 5% on pipe, 8% on fittings, labour costed from the estimated man-days rather than a flat percentage), and say so. Under-pricing wastage to look cheap is the commonest way small contractors lose money on school work.
- Offer a value choice rather than a discount: give one price for the full specification and a second only if the client chooses to defer the hot-water branch to the staff room, with the pipe route and valves left provisioned. That keeps the bid competitive without cutting safety or quality.
- Explain the risk in one line: "The lower figure I could give you would leave out the risers or use CPVC where it is not needed; it would be corrected at site as an extra, and you would pay more later." Submit on time, in writing, with the measurement sheet attached, and keep a copy of what was quoted - that record is what protects both the school and the firm.