The £481,954.33 baseline tender total broken into its eight cost layers. Materials dominate (51% — driven by the IDEAL cascade and Stokvis PHE skids). Labour and OH&P each account for ~17% and ~8% respectively. Sub-let (LARC asbestos, BMS PC Sum, crane) is 9%.
Cumulative build-up from £0 to £481,954, layer by layer. Each segment is sized proportionally and labelled with its £ value. The order reflects estimating practice: direct costs first (materials, labour, plant, sub-let), then site overheads, then provisional sums, then risk, then OH&P applied last.
Each BoQ section's £ total broken down into its layer composition. Section F (Mech & PH, £296,990) is heavily material-led — the IDEAL cascade and Stokvis skids dominate. Section C (Strip-Out) is sub-let-heavy — LARC asbestos removal sits there. Section A (Prelims) is labour and plant.
Five representative BoQ line items with their full layer-by-layer working. Each card shows the components (descriptions, quantities, rates, net values, layer assignment), the direct cost subtotal with layer-mix pills, the risk addition, the OH&P uplift, and the final tender rate. The first two are open by default.
One of three boilers in the cascade. Material from SBS Quote 18-SQ0023969 Ver 1; install labour from in-house mechanical team at engineer + fitter all-in rates.
| Description | Qty | Unit | Rate £ | Net £ | Layer |
|---|---|---|---|---|---|
| IDEAL EVO Max 2 boiler unit (SBS net price) | 1 | No. | 22,500.00 | £22,500.00 | MAT |
| Mounting frame, ancillaries, gaskets, isolators | 1 | item | 685.00 | £685.00 | MAT |
| Install labour — Mech Engineer (lead) | 12 | hrs | 58.00 | £696.00 | LAB |
| Install labour — Mech Fitter ×2 | 24 | hrs | 52.00 | £1,248.00 | LAB |
| Materials handling allowance (forklift, plinth) | 1 | LS | 220.00 | £220.00 | PLT |
| Direct cost (sum of lines) | £25,349.00 | MAT: £23,185LAB: £1,944PLT: £220 |
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| + Risk allowance (4.0%) | £1,013.96 | RSK | |||
| + Overhead & Profit (7.5%) | £1,977.22 | OHP | |||
| TENDER RATE per No. | £28,340.18 | ||||
Pure sub-let to a separately-appointed Licensed Asbestos Removal Contractor. Built AI carries supervision allowance and on-cost only (CAR 2012 designer duties).
| Description | Qty | Unit | Rate £ | Net £ | Layer |
|---|---|---|---|---|---|
| LARC quote (3 quotes received; mid-quote selected) | 1 | LS | 9,850.00 | £9,850.00 | SUB |
| Built AI supervision attendance — H&S adviser | 8 | hrs | 64.00 | £512.00 | LAB |
| Cert. of Reoccupation handling, document review | 4 | hrs | 64.00 | £256.00 | LAB |
| Direct cost (sum of lines) | £10,618.00 | SUB: £9,850LAB: £768 |
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| + Risk allowance (5.0%) | £530.90 | RSK | |||
| + Overhead & Profit (6.0%) | £668.93 | OHP | |||
| TENDER RATE per LS | £11,817.83 | ||||
Sub-let crane contractor for the single 5-day Phase 4 lift-in operation. Lift plan + Appointed Person + crew + crane + rigging. Weather-window risk explicit.
| Description | Qty | Unit | Rate £ | Net £ | Layer |
|---|---|---|---|---|---|
| Crane hire — 50 t mobile, 5 days incl. mob/demob | 1 | wk | 2,850.00 | £2,850.00 | SUB |
| Appointed Person (CPCS) — daily attendance | 5 | days | 460.00 | £2,300.00 | SUB |
| Lifting accessories — slings, shackles, beam | 1 | LS | 580.00 | £580.00 | PLT |
| Built AI Site Sup. attendance during lifts | 40 | hrs | 56.00 | £2,240.00 | LAB |
| TWC plan + permit | 1 | LS | 320.00 | £320.00 | LAB |
| Direct cost (sum of lines) | £8,290.00 | SUB: £5,150PLT: £580LAB: £2,560 |
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| + Risk allowance (8.0%) | £663.20 | RSK | |||
| + Overhead & Profit (7.0%) | £626.72 | OHP | |||
| TENDER RATE per LS | £9,579.92 | ||||
Labour-heavy line item — typical mech-services insulation per linear metre. Material cost steady; labour rate dependent on access/height.
| Description | Qty | Unit | Rate £ | Net £ | Layer |
|---|---|---|---|---|---|
| Phenolic foam insulation (50mm wall, BS 5422) | 65 | LM | 12.50 | £812.50 | MAT |
| Foil jacketing, banding, ID labelling kit | 65 | LM | 4.20 | £273.00 | MAT |
| Insulation fitter (skilled) — installation | 22 | hrs | 48.00 | £1,056.00 | LAB |
| Insulation labourer (assist) — handling | 22 | hrs | 32.00 | £704.00 | LAB |
| MEWP allocation (pro-rata of 2-week hire) | 1 | LS | 145.00 | £145.00 | PLT |
| Direct cost (sum of lines) | £2,990.50 | MAT: £1,086LAB: £1,760PLT: £145 |
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| + Risk allowance (3.0%) | £89.72 | RSK | |||
| + Overhead & Profit (8.0%) | £246.42 | OHP | |||
| TENDER RATE per LM | £3,326.63 | ||||
Material at OEM trade discount via wholesaler; install labour by NICEIC-registered electrician. Test & certification covered separately at G9.
| Description | Qty | Unit | Rate £ | Net £ | Layer |
|---|---|---|---|---|---|
| Schneider Acti 9 DB — 12-way 125 A TP&N + RCBOs | 1 | No. | 1,820.00 | £1,820.00 | MAT |
| Sub-main cable termination kit + glands | 1 | set | 165.00 | £165.00 | MAT |
| Electrician (Approved) — installation + termination | 12 | hrs | 56.00 | £672.00 | LAB |
| Mate / labourer — assistance | 8 | hrs | 36.00 | £288.00 | LAB |
| Direct cost (sum of lines) | £2,945.00 | MAT: £1,985LAB: £960 |
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| + Risk allowance (3.0%) | £88.35 | RSK | |||
| + Overhead & Profit (8.0%) | £242.67 | OHP | |||
| TENDER RATE per No. | £3,276.02 | ||||
The £8,050 risk pot (1.7% of tender total) is allocated against specific identified risks — not a flat percentage on everything. Risks that are properly transferable via Provisional Sums are excluded from the pot to avoid double-counting.
Cost Stack closed and signed off. Layer build-up reconciles to £481,954.33 against the priced BoQ Rev 1. Two-pass QS review complete (Estimator + Commercial Mgr). The stack is now ready for the final pre-submission gate.
Cost Stack™ is the fourth stage of the Bidroom in a Box™ workflow. It builds every priced line item from its component layers — material, labour, plant, sub-let, prelims, provisional sum, risk, OH&P — and reconciles them to the BoQ subtotals. Risk and margin are applied at line-item level, never bottom-loaded. The output feeds Priced BoQ Rev 1, the value-engineering options register, and the final commercial position carried into Last Look™.