Quantity Deviation of 31% and an Extra Item With No BOQ Rate
An RCC framed office building was tendered on a percentage-rate BOQ containing 180 m³ of M25 RCC in foundation and plinth at Rs 7,850/m³, and 240 m³ of M25 RCC in columns and beams at Rs 8,420/m³. During execution the structural consultant revised the raft thickness and the footing sizes, and the measured quantity of the foundation item rose to 236 m³. The contract has a deviation clause: quantities beyond ±25% of the BOQ may be paid at a revised rate, with the contractor's rate reduced by 10% for quantity in excess of 25%. Separately, the client instructed 12 m³ of 75 mm thick PCC 1:4:8 as a levelling course under the raft, for which no BOQ item exists. Prevailing rates: cement Rs 400 per 50 kg bag, sand Rs 1,800/m³, 40 mm aggregate Rs 1,300/m³, labour Rs 550/m³ of PCC; the tender was quoted at 8% above the schedule of rates. The contractor claims the full tender rate on all 236 m³ and Rs 6,200/m³ for the extra PCC.
1. Compute the amount payable for the foundation item under the deviation clause, and decide whether applying the rate reduction is the right call. Address the scope-change argument.
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Arithmetic: deviation = (236 − 180) / 180 = +31.1%, beyond ±25%. The 25% band is 45 m³, so the tender rate applies up to 225 m³; only the 11 m³ beyond that attracts the reduction.
- 225 m³ × Rs 7,850 = Rs 17,66,250
- 11 m³ × Rs 7,850 × 0.90 = Rs 77,715
- Total = Rs 18,43,965
Compare with no revision: 236 × 7,850 = Rs 18,52,600. The reduction saves Rs 8,635, or 0.47% of the item - less than the cost of processing the variation and certain to be disputed. Record the computation in the measurement book so the client's audit position is protected, but do not spend political capital enforcing it.
The real question is the trigger. A deviation clause is written for a BOQ quantity error, where the contractor's fixed costs are spread over an assumed quantity. Here the raft and footings were revised by the structural consultant - a client-instructed design change that the contractor could not have priced at tender. In that situation the usual and fair position is the full tender rate on the entire 236 m³: the contractor is not recovering an error, he is being asked to build something different, and the 10% reduction becomes an arbitrary penalty. Check the contract wording - variation versus deviation - and the instruction date and revision drawing number. My recommendation: pay full rate, but only after the revised drawing and the joint measurement are on record, and note that the same logic does not extend to the extra PCC item, which must be rate-analysed.
2. Build a rate analysis for the extra item and evaluate the claim of Rs 6,200/m³, including how the 8% above the schedule of rates should be treated.
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Rate analysis for 1 m³ of PCC 1:4:8 (nominal mix, dry volume factor 1.52, cement at 1,440 kg/m³):
| Item | Working | Amount |
|---|---|---|
| Cement | 1.52/13 = 0.1169 m³ = 168 kg = 3.37 bags × Rs 400 | Rs 1,348 |
| Sand | 1.52 × 4/13 = 0.4677 m³ × Rs 1,800 | Rs 842 |
| 40 mm aggregate | 1.52 × 8/13 = 0.9354 m³ × Rs 1,300 | Rs 1,216 |
| Labour (mixing, placing, compacting, curing) | - | Rs 550 |
| Direct cost | - | Rs 3,956 |
| Water charges at 1% | - | Rs 40 |
| Overheads and profit at 10% | - | Rs 400 |
| Rate per m³ | - | about Rs 4,400 |
For 12 m³ that is about Rs 52,750.
Evaluating Rs 6,200/m³: it is 41% above the analysis and needs a breakdown. A 75 mm levelling course involves no formwork and no reinforcement, so the only legitimate additions are a small-quantity loading on 12 m³ (perhaps 5–10%) and any long lead or pumping. Even with 10% added, Rs 4,840/m³ is the ceiling - roughly Rs 58,100 for the lot.
Handling the 8%: if the item is built from the schedule of rates, the tender percentage applies once - SSR ≈ 4,400 / 1.08 ≈ Rs 4,070/m³, and 4,070 × 1.08 = Rs 4,396/m³. If instead the rate is built from first principles, the 10% overheads and profit already contains the margin, and adding the 8% again would be double counting. State which basis is being used in the determination; a percentage-rate tender is a level adjustment, not an extra on top of a market rate analysis. Approve Rs 4,400/m³ or the SSR-derived equivalent, and get the rate agreed in writing before the work is executed.
3. What records and procedure would you insist on so that both claims survive an audit and a possible dispute?
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For both the deviation item and the extra item:
- Written instruction from the client or the client's representative for the revised raft dimensions and for the PCC levelling course, with date, drawing number and revision number - without this, the extra item is unauthorised work and can be refused outright.
- Joint measurement entered in the measurement book on the same day as the work, signed by the contractor's and the engineer's representatives, with sketches of the revised footing and raft dimensions so the 236 m³ can be reconstructed later.
- Rate analysis showing quoted material rates supported by invoices, and labour rates taken from the prevailing minimum wage notification, not from memory. Attach the current schedule of rates extract.
- Deviation computation sheet showing the 25% band, the quantity in each band, and the rate applied, so the Rs 18,43,965 is traceable line by line.
- Prior approval of the extra-item rate, not a retrospective determination after the concrete has been poured. An after-the-fact negotiation always costs more.
- Correspondence trail with the contractor's claim and the engineer's determination, including reasons for accepting or rejecting each element. A determination that says only rejected is indefensible; one that says rejected because the claimed 41% premium is not supported by the analysis is.
If agreement is not reached, refer the matter under the dispute-resolution clause rather than unilaterally adjusting the bill - an unauthorised deduction will be reversed later with interest.