Article 4: Contractor Estimating and Tender Pricing
Introduction
The previous articles in this series have looked at estimating from the client’s side — the quantity surveyor building cost plans, benchmarking against BCIS data, and refining estimates through design stages. This article crosses to the other side of the table. Contractor estimating is a fundamentally different exercise: it starts not from benchmarks and elemental rates but from first principles — the actual cost of labour, materials, plant, and subcontractors needed to build the project.
This is where estimating meets production. The contractor’s estimator must calculate what it will truly cost to put a building together, accounting for gang productivity, material waste, plant standing time, site constraints, and subcontractor risk. The result is not a cost plan but a tender price — a commercial offer that the contractor is bound by if accepted. Get it wrong, and the contractor either loses the job (priced too high) or loses money building it (priced too low).
This article — the fourth in the estimating series — explains the full contractor estimating workflow, from the bid/no-bid decision through to management adjudication and final tender submission. It covers all-in labour rate calculations, first-principles rate build-ups, subcontractor procurement, preliminaries pricing, and the application of overheads and profit. The entire process is illustrated through Project Parkside, showing how a contractor builds a tender price of £3,950,000 — and why that figure differs from the QS’s pre-tender estimate of £4,103,000.
How Contractor Estimating Differs from Cost Planning
The QS’s cost plan and the contractor’s estimate answer different questions. The QS asks: what should this building cost? The contractor asks: what will it cost me to build it?
The QS works from benchmarks and elemental unit rates — historical cost data adjusted for location, specification, and inflation. The contractor works from first principles — the actual hourly rate of a bricklayer, the delivered price of a tonne of concrete, the weekly hire cost of a tower crane. The QS prices elements (substructure, superstructure, services); the contractor prices operations (dig foundations, pour concrete, lay bricks, install pipework).
There is a further critical distinction. The QS’s estimate is advisory — it informs the client’s budget and benchmarks the tenders when they arrive. The contractor’s tender is contractually binding. Once submitted, the contractor is committed to delivering the building for that price (subject to contract provisions for variations and claims). This changes everything about how the estimate is built: conservatism must be balanced against competitiveness, because the estimate that wins the job is the one the contractor must live with.
Within the contractor’s organisation, there is also a separation of roles. The estimator calculates the net cost — the true cost to build. Senior management then applies overheads, profit, and commercial judgement to arrive at the tender price. The estimator’s job is accuracy; management’s job is strategy. The CIOB Code of Estimating Practice is explicit on this point: the estimate should reflect cost reality, not commercial aspiration.
The Contractor Estimating Workflow
The contractor’s estimating process runs from tender receipt through bid submission, typically over four to eight weeks depending on project complexity. The workflow follows a structured sequence, each stage building on the last.
| Stage | Activity | Key Output |
|---|---|---|
| 1 | Bid/no-bid decision — evaluate the tender opportunity against workload, project type, client, competition, and risk | Decision to proceed or decline |
| 2 | Document review — examine tender documents, drawings, BoQ, specification; identify queries and ambiguities | Enquiry list to client QS |
| 3 | Site visit and appraisal — inspect the site for access, ground conditions, logistics, constraints | Site appraisal report with photographs |
| 4 | Subcontractor and supplier enquiries — send scope packages to specialist trades and material suppliers | Enquiry packages issued; response tracker |
| 5 | Quantity take-off — measure quantities from drawings (or price the client-provided BoQ) | Measured quantities by trade/element |
| 6 | Rate build-up — calculate all-in rates for labour, materials, and plant from first principles | Priced rate schedule |
| 7 | Subcontractor evaluation — compare returned quotes on price, scope, programme, and risk | Preferred subcontractor selection |
| 8 | Preliminaries pricing — calculate site-running costs (management, plant, scaffolding, insurance, welfare) | Preliminaries summary |
| 9 | Management adjudication — directors review the net cost estimate and apply overheads, profit, and commercial adjustments | Final tender price |
| 10 | Bid submission — submit priced documents, method statement, programme, and supporting information by the deadline | Tender submission |
The first eight stages produce the net cost estimate — what the project will actually cost the contractor to deliver. Stage 9 transforms that into the tender price by adding overheads and profit. This separation is deliberate: the estimator’s job is to calculate cost objectively, without commercial pressure to hit a particular number.
The Bid/No-Bid Decision
Before committing estimating resources to a tender, the contractor must decide whether the opportunity is worth pursuing. This is not a casual decision — a full tender for a £4M project might consume 200–300 hours of estimator time plus management input. Bidding on every opportunity is neither practical nor commercially sensible.
Large contractors often score tender opportunities against a weighted checklist. The factors typically considered include current workload and capacity, familiarity with the project type, site location, client reputation, level of competition, contract terms and risk profile, and the strategic importance of the project. Each factor is scored and weighted to produce an overall assessment.
Project Parkside: Bid/No-Bid Assessment
| Factor | Weight | Score (1–5) | Assessment |
|---|---|---|---|
| Workload and capacity | 20% | 4 | Moderate capacity available; can resource a 32-week programme |
| Project type familiarity | 15% | 5 | Standard residential — the contractor’s core market |
| Location | 15% | 4 | Salford — within the contractor’s North West base |
| Client relationship | 15% | 4 | Repeat housing association client with good payment record |
| Competition level | 10% | 3 | Five contractors on the tender list — competitive but not crowded |
| Contract terms | 10% | 4 | JCT Standard Form — familiar, balanced risk allocation |
| Risk profile | 10% | 3 | Moderate — ground conditions partly investigated; standard specification |
| Strategic importance | 5% | 4 | Repeat client; opportunity for follow-on work |
Weighted score: 3.95 out of 5. This is a strong opportunity — familiar project type, known client, manageable risk. The contractor decides to bid with a target profit margin of 5%, reflecting a competitive but not desperate position.
Building All-In Rates: The Labour Calculation
The all-in labour rate is the foundation of contractor estimating. It converts the base hourly wage published in industry agreements into the true cost per productive hour — accounting for employer’s National Insurance, pension contributions, holiday pay, sick pay, training, and the reality that not every hour on site is a productive hour.
The starting point is the relevant working rule agreement. For general construction trades, this is the CIJC (Construction Industry Joint Council) Working Rule Agreement, which sets minimum rates for labourers, skilled operatives, plant operators, and supervisors. Specialist trades have their own agreements — NAECI for electrical, JIB for plumbing, and JCWCC for carpentry — but the build-up methodology is the same.
Worked Example: Skilled Operative (Bricklayer)
| Component | Calculation | Annual Cost |
|---|---|---|
| Base wage (CIJC skilled operative, 2025/26) | £13.25/hr × 1,950 hrs/year | £25,838 |
| Employer’s National Insurance (15% above £5,000) | (£25,838 − £5,000) × 15% | £3,126 |
| Workplace pension (auto-enrolment, 3%) | £25,838 × 3% | £775 |
| Holiday pay (30 days = 225 hrs) | 225 hrs × £13.25 | £2,981 |
| CITB levy (0.5% of payroll) | £25,838 × 0.5% | £129 |
| Sick pay provision (~4 days) | 30 hrs × £13.25 | £398 |
| Tool money, travel, and training | Allowances | £665 |
| Total annual cost to contractor | £33,912 | |
| Productive hours per year | 1,950 − 390 non-productive | 1,560 hrs |
| All-in hourly rate | £33,912 ÷ 1,560 | £21.74 |
The 390 non-productive hours deducted include bank holidays (60 hours), annual leave (225 hours), sickness absence (30 hours), training and induction (15 hours), and weather downtime and site stoppages (60 hours). These are hours the contractor pays for but receives no productive output.
The same calculation for a general labourer at the CIJC base rate of £11.89/hour produces an all-in rate of approximately £19.50/hour. The gap between the base wage and the all-in rate is substantial — for the skilled operative, the all-in rate is 64% above the CIJC base rate. This is why contractors who estimate using base wages alone systematically under-price their labour.
A note on employer’s National Insurance: from April 2025, the rate increased to 15% with the threshold reduced to £5,000 (from the previous 13.8% above £9,100). This increased employer costs by roughly £1,200 per operative per year — a material change that feeds directly into all-in rates and ultimately into tender prices.
Rate Build-Up Worked Example: Brickwork
With the all-in labour rate established, the estimator can build a complete unit rate for any measured item. This worked example shows how a rate is constructed for 1m² of 102.5mm facing brickwork in stretcher bond — a common item on Project Parkside’s external walls.
Labour
The standard gang for facing brickwork is two bricklayers and one labourer. The labourer mixes mortar, carries materials to the work face, and keeps the bricklayers supplied. A typical gang output for this specification is 10m² per day in 6.5 productive hours (the remaining 1.5 hours of the 8-hour day are spent on setting out, moving scaffolding, checking levels, and breaks).
The gang cost per productive day is (2 × £21.75 × 6.5) + (1 × £19.50 × 6.5) = £282.75 + £126.75 = £409.50. Spread over 10m² of output, the labour cost is £41/m².
Materials
Each square metre of 102.5mm brickwork in stretcher bond requires approximately 60 bricks. At a delivered price of £400 per thousand for facing bricks (North West, Q1 2026), that is £24.00/m². Mortar adds approximately £8/m², and sundries (wall ties, DPC, lintels on a pro-rata basis) add £2/m². A 5% waste allowance on materials adds £1.70/m². Total materials: £36/m².
Plant
For brickwork, plant costs are minimal — typically limited to a mobile elevated work platform (MEWP) for upper-level access. Most plant (scaffolding, hoists, tower crane) is priced in preliminaries rather than allocated to individual trades. The estimator allows £1/m² for minor plant items.
Complete Rate Build-Up
| Cost Element | Rate per m² | Notes |
|---|---|---|
| Labour (2 bricklayers + 1 labourer) | £41.00 | Gang output 10m²/day; all-in rates applied |
| Materials (bricks, mortar, sundries) | £36.00 | Including 5% waste allowance |
| Plant (MEWP access) | £1.00 | Scaffolding in preliminaries |
| Net rate | £78.00 | Before contingency |
| Productivity contingency (3%) | £2.34 | Allowance for weather and rework |
| All-in rate | £80.34 | Say £80/m² |
This rate compares to the QS’s elemental benchmark of approximately £85–95/m² for the same specification. The contractor’s rate is lower because it reflects actual gang productivity and negotiated material prices rather than BCIS averages. This kind of difference — 5–15% below benchmark — is typical and is one reason contractor tenders often come in below the QS’s pre-tender estimate.
The estimator repeats this build-up for every measured item: concrete foundations, roof coverings, internal partitions, floor finishes, drainage, and so on. For a project the size of Parkside, the priced schedule might contain 150–300 individual rates.
Subcontractor Procurement
Not all work is priced from first principles. Specialist trades — MEP installations, structural steelwork, piling, lift installation, curtain walling — are typically procured from domestic subcontractors. The estimator sends enquiry packages to three to five subcontractors per trade, including the scope of work extracted from the tender drawings, key programme dates, site constraints, and contract terms.
Subcontractor quotations are evaluated on more than price alone. The estimator assesses scope completeness (does the quote cover everything, or are there exclusions?), programme fit (can the subcontractor deliver on the required dates?), financial stability, and track record on similar projects. The cheapest quote is not always the best — a subcontractor who excludes testing and commissioning or who cannot meet the programme creates risk that far outweighs a 5% saving on the quoted price.
Once a preferred subcontractor is selected, the contractor adds an uplift — typically 7–12% — to cover main contractor supervision, health and safety compliance, procurement overhead, risk allowance, and a profit element. For known and reliable subcontractors, the uplift sits at the lower end; for new or higher-risk subcontractors, it is higher.
For Project Parkside, the major subcontract packages are electrical installation (£420,000), mechanical services and heating (£380,000), plumbing and drainage (£285,000), structural frame (£310,000), and roofing (£165,000). These subcontract values include the contractor’s uplift and account for approximately 50% of total trade costs — a typical proportion for a residential project of this specification.
Pricing Preliminaries
Preliminaries — or “prelims” — are the site-running costs that are not direct to any single trade but are essential to deliver the project. They include site management salaries, site accommodation, temporary services, general-use plant, scaffolding, insurance, health and safety provision, and waste management. The estimator prices each item individually, distinguishing between time-related costs (which depend on programme duration) and fixed costs (which do not).
Project Parkside: Preliminaries Build-Up
| Item | Basis | Cost |
|---|---|---|
| Site management | ||
| Site manager | 32 weeks @ £900/week | £28,800 |
| Assistant site manager | 32 weeks @ £600/week | £19,200 |
| Site accommodation | ||
| Office cabin and welfare facilities | 32 weeks @ £430/week | £13,760 |
| Temporary services | ||
| Power and water supply | 32 weeks @ £230/week | £7,360 |
| Scaffolding | ||
| Access scaffolding (2,500m²) | 32 weeks @ £1.50/m²/week | £120,000 |
| Tower crane | ||
| 500kg/50m jib crane | 24 weeks @ £2,000/week | £48,000 |
| Insurance and testing | ||
| Public liability, contract works, inspections | Lump sums | £28,000 |
| Health and safety | ||
| Induction, PPE, welfare, first aid | 32 weeks + lump sums | £7,200 |
| Environmental and waste | ||
| Skips, recycling, dust suppression | 32 weeks @ £550/week | £17,600 |
| Mobilisation and demobilisation | ||
| Site set-up, fencing, final clearance | Lump sums | £14,000 |
| Total preliminaries | £310,000 |
Preliminaries on Project Parkside represent approximately 9.4% of trade costs (£310,000 on £3,290,000). This is within the typical range for a 4-storey residential project of 8–12%. The largest single item is scaffolding (£120,000) — a common feature of multi-storey residential work where the full external envelope requires access scaffolding for the duration of the superstructure and envelope phases.
Programme duration is the biggest driver of preliminary costs. If the programme extends from 32 weeks to 40 weeks, time-related prelims increase by approximately £50,000 — equivalent to wiping out the contractor’s entire risk allowance. This is why contractors guard their programme fiercely and why programme delays have such a disproportionate impact on profitability.
Overheads and Profit
The net cost estimate — trade costs plus preliminaries plus risk allowance — represents what the project will cost the contractor to build. But it does not cover the contractor’s head office overheads (office rent, management salaries, IT, insurance, professional services) or provide any profit. These are added as percentage uplifts on the net cost.
Overheads
Company overheads are the costs of running the business that are not attributable to any single project. A mid-size contractor with annual turnover of £25–40M might carry annual overheads of £800,000–£1,200,000. The overhead recovery percentage is calculated as total overheads divided by total turnover — typically 3–4% for a well-run contractor. Each project must contribute its share, otherwise the business operates at a loss regardless of how well individual projects are delivered.
Profit
Profit is the return to the business (and ultimately to shareholders) for taking on the risk of construction. It is distinct from overheads: overheads must be recovered for the business to survive; profit is earned for delivering efficiently and managing risk successfully. Typical profit margins in UK construction (2025/26) range from 1–3% in highly competitive markets to 7–15% in a seller’s market. For a competitive tender with five bidders, 4–6% is the normal range.
Project Parkside: OH&P Calculation
| Item | Calculation | Amount |
|---|---|---|
| Total trade costs | Own trades + subcontractors | £3,290,000 |
| Preliminaries | Site-running costs (32-week programme) | £310,000 |
| Risk allowance (1.5%) | Ground conditions and programme risk | £55,000 |
| Net cost | £3,655,000 | |
| Overheads (3%) | Head office cost recovery | £110,000 |
| Profit (5%) | Competitive market; repeat client | £185,000 |
| Tender price | £3,950,000 |
The combined OH&P of 8% (£295,000) is typical for a competitive residential tender. If the contractor were bidding in a less competitive scenario — say a two-contractor shortlist with a strong client relationship — the profit element might increase to 7–8%, pushing OH&P to 10–11%.
Management Adjudication
The management adjudication is where the estimate becomes a tender. After the estimator completes the net cost calculation, the estimate goes to a formal review meeting attended by the commercial director, estimating manager, contracts manager, and sometimes the finance director. This meeting serves three purposes.
First, sense-checking the estimate. Does the net cost look right for a project of this size and type? If the cost per square metre is significantly above or below the contractor’s historical range, the team investigates. For Project Parkside, the net cost of £3,655,000 equates to £1,828/m² GIFA — within a reasonable range for 4-storey residential in the North West.
Second, identifying and pricing risk. The team reviews the key risk items: are ground conditions fully investigated? Is the programme realistic? Are subcontractor quotes firm or indicative? Are there design ambiguities that could generate variations? The risk allowance of £55,000 (1.5% of net cost) reflects a moderate risk profile — the ground investigation is partly complete, and the contract is JCT Standard Form with a clear claims mechanism.
Third, setting the commercial position. The directors decide how much overhead and profit to add, informed by workload (can we resource this project?), market conditions (how competitive are we likely to be?), and strategic factors (is this client important for future work?). For Parkside, the contractor adds 3% overheads and 5% profit — a competitive but not aggressive position, reflecting the repeat-client relationship and moderate competition.
The adjudication meeting might also make tactical adjustments. If the estimator has identified scope ambiguities, the directors may decide to price those items conservatively (allowing for a later variation claim) or aggressively (to sharpen the tender price). They may also redistribute margin between different parts of the tender — for example, loading more profit into early-programme items to improve cash flow, a practice known as front-loading.
Project Parkside: Full Tender Build-Up
Bringing together all the elements, the contractor’s complete tender for Project Parkside breaks down as follows.
| Cost Category | Amount | % of Tender |
|---|---|---|
| Facilitating works (own trade) | £40,000 | 1.0% |
| Substructure (own trade) | £385,000 | 9.7% |
| Superstructure — frame (subcontract) | £310,000 | 7.8% |
| Superstructure — envelope and roof (mixed) | £525,000 | 13.3% |
| Internal finishes (own trade) | £290,000 | 7.3% |
| Fittings — kitchens and bathrooms (subcontract supply; own install) | £155,000 | 3.9% |
| Services — electrical (subcontract) | £420,000 | 10.6% |
| Services — mechanical and heating (subcontract) | £380,000 | 9.6% |
| Services — plumbing and drainage (subcontract) | £285,000 | 7.2% |
| External works (own trade) | £165,000 | 4.2% |
| Stairs, balconies, and miscellaneous (mixed) | £60,000 | 1.5% |
| Subcontractor uplift (supervision, H&S, risk) | £275,000 | 7.0% |
| Total trade costs | £3,290,000 | 83.3% |
| Preliminaries (site management, plant, scaffolding, insurance) | £310,000 | 7.8% |
| Risk allowance (ground conditions, programme) | £55,000 | 1.4% |
| Net cost | £3,655,000 | 92.5% |
| Overheads (3% — head office recovery) | £110,000 | 2.8% |
| Profit (5% — competitive market, repeat client) | £185,000 | 4.7% |
| Tender price | £3,950,000 | 100% |
The tender price of £3,950,000 equates to £1,975/m² GIFA. Services account for the largest share of trade costs (27.4% of the tender), followed by the superstructure (21.1%) and substructure (9.7%). This distribution is consistent with a 4-storey residential project where MEP installations are a major cost driver.
Contractor vs QS: Why the Numbers Differ
The contractor’s tender of £3,950,000 comes in £153,000 (3.7%) below the QS’s pre-tender estimate of £4,103,000. This is a healthy outcome — the tender is within the QS’s accuracy range (±3–5% at CP3) and below the client’s budget. But why is the contractor lower?
| Factor | QS Estimate | Contractor Tender | Difference |
|---|---|---|---|
| Labour rates | BCIS benchmark averages | Actual all-in rates from first principles | Contractor’s own rates are typically 5–10% below BCIS averages for trades they perform regularly |
| Material prices | Published price books and BCIS data | Negotiated supplier quotes (bulk pricing, relationship discounts) | Contractor achieves 3–8% savings through direct procurement |
| Subcontractor costs | Elemental unit rates (broad brush) | Competitive quotes from 3–5 subcontractors per trade | Competition between subcontractors drives prices below benchmark |
| Contingency | 5–8% at CP3 stage | 1.5% risk allowance | Contractor carries less contingency — risk is priced into individual rates and managed through the contract |
| Preliminaries | Percentage-based (6% of building cost) | Item-by-item build-up (9.4% of trade costs) | Contractor prices prelims in detail; QS uses a lower percentage but may underestimate |
| OH&P | Not included (cost plan, not tender) | 8% (3% OH + 5% profit) | Contractor adds commercial margin not in QS estimate |
The net effect is that the contractor’s tighter cost knowledge and competitive procurement more than offset the addition of overheads and profit. The QS’s contingency allowance (which the contractor does not carry to the same extent) is the largest single driver of the gap. This is by design — the QS’s estimate is deliberately conservative to protect the client’s budget, while the contractor’s tender reflects the price at which they are willing to commit to delivery.
From the QS’s perspective, a tender 3.7% below the pre-tender estimate is an excellent result. It suggests the cost plan was well-calibrated — close enough to be credible but sufficiently above the market to provide the client with budget comfort. A tender that significantly exceeds the pre-tender estimate (by more than 5–10%) would indicate either that the QS’s estimate was too low or that market conditions have moved since the cost plan was prepared.
Common Contractor Estimating Errors
Contractor estimating errors fall into two categories: errors of omission (missing costs entirely) and errors of judgement (pricing costs incorrectly). Both can be fatal to project profitability.
Under-pricing preliminaries is the most common structural error. Estimators under pressure to produce a competitive tender often trim preliminaries first — reducing the site manager allocation from 32 weeks to 28, omitting dust suppression, or assuming welfare facilities can be shared with an adjacent project. The result is a tender that looks competitive but leaves the site under-resourced from day one.
Missing scope items from the tender drawings is an error of diligence. Lintels, sills, flashings, junctions between elements, testing and commissioning, and external works are frequently omitted or under-measured. A structured quantity take-off checklist, cross-referencing architectural, structural, and MEP drawings, is the best defence.
Over-optimistic productivity assumptions are an error of experience. An estimator who assumes brickwork output of 12m² per gang per day when site conditions realistically support 10m² will under-price every square metre of facing brickwork on the project. Productivity must be adjusted for site-specific factors: weather exposure, scaffolding access, building geometry, and the quality of the labour force available.
Stale subcontractor quotations are a timing risk. A quote obtained in week two of a six-week tender period may be 3–5% out of date by the time the tender is submitted, particularly for materials subject to commodity price volatility (steel, copper, concrete). The estimator should confirm prices with preferred subcontractors in the final week before submission.
No site visit is an error of process. The estimator who prices from drawings alone will miss access constraints, ground conditions, adjacent activity, overhead power lines, conservation restrictions, and a dozen other site-specific factors that affect cost. The CIOB Code of Estimating Practice treats the site visit as mandatory, not optional.
Using outdated rates is an error of discipline. Labour rates, material prices, and plant hire costs change annually. An estimator using 2023 labour rates in a 2026 tender will systematically under-price every item by 10–15%. All benchmark rates should be refreshed at least annually, and key rates (concrete, steel, labour) should be verified against current supplier quotes for each tender.
The CIOB Code of Estimating Practice
The CIOB (Chartered Institute of Building) Code of Estimating Practice is the standard professional guidance for contractor estimators in the UK. It establishes the principles and procedures that underpin good estimating practice, covering the full workflow from bid/no-bid decision through to tender submission.
The Code’s key principles are worth stating explicitly. Accuracy: the estimate should reflect the true cost to build, not a target or aspiration. Completeness: all items of cost should be included; nothing left to assumption. Audit trail: every figure in the estimate should be traceable to a source — a supplier quote, a labour rate calculation, a productivity assumption. Independence: the estimator’s job is to calculate cost objectively; commercial adjustments are management’s responsibility, applied separately and transparently. Risk identification: foreseeable risks should be identified and quantified specifically, not buried in a blanket contingency percentage.
The Code also recommends that each tender be supported by an Estimating Plan — a brief document setting out the project scope, the estimating approach, key assumptions, risk items, the tender programme, and the team responsible. This is good practice for any tender but is particularly valuable on complex or high-value projects where the estimating process itself needs to be managed.
Practical Tips for QS Professionals
For client-side QS professionals, understanding how contractors build their tenders makes you better at writing cost plans, assessing tenders, and negotiating post-tender. If you know that a contractor’s brickwork rate is built from a gang output of 10m² per day and an all-in labour rate of £21.75/hour, you can sense-check their rates against your own benchmarks with much greater precision. You can also identify where a contractor has priced aggressively (thin preliminaries, optimistic productivity) versus conservatively (high risk allowance, generous waste factors).
For contractor-side QS professionals, the estimator is your most important colleague. The quality of the estimate determines whether the project starts with a realistic budget or an impossible one. Challenge productivity assumptions, verify subcontractor quotes, and stress-test the preliminaries build-up — these are the areas where estimating errors most commonly arise and where the commercial team can add the most value during the tender process.
For students, the key takeaway from this article is the difference between benchmark-based estimating (QS) and first-principles estimating (contractor). Both are valid; both are necessary. The QS’s cost plan provides the client with a budget framework; the contractor’s tender provides the price at which the building will actually be built. The gap between them — typically 3–10% on a well-managed project — reflects the difference between cost planning and cost commitment.
What’s Next
The next article in this series — Factors Affecting Estimates and Cost Accuracy — examines the variables that cause estimates to change: location, market conditions, procurement route, specification, programme, and the inherent uncertainty in construction. It explores why two competent estimators pricing the same project can produce figures 10–15% apart, and what the QS can do to manage that uncertainty through the life of a project.
Series Cross-References
Article 1: Introduction to Estimating in Construction — what estimating is, why it matters, and how estimates evolve through the project lifecycle.
Article 2: Types of Estimates and When to Use Them — from order-of-magnitude through to detailed estimates, with the full Project Parkside cost evolution.
Article 3: Elemental Cost Planning (Client-Side) — the NRM 1 framework, BCIS benchmarking, and how the QS builds cost plans from CP1 through CP3.
Article 5: Factors Affecting Estimates and Cost Accuracy — location, procurement, specification, market conditions, and managing estimating uncertainty. (Coming next)
Article 6: Technology in Estimating — digital take-off, BIM integration, estimating software, and the future of cost data. (Coming soon)
External References
CIOB — Chartered Institute of Building — professional body for construction managers and estimators; publisher of the Code of Estimating Practice.
RICS NRM Standards — the New Rules of Measurement framework for cost estimation and cost planning.
RIBA Plan of Work 2020 — the design stage framework that aligns with both QS cost plans and contractor tender programmes.
BCIS — Building Cost Information Service — the benchmark cost data source used by both QS professionals and contractors for rate verification.