Source: https://www.quantsurv.com/library/construction-estimating-mistakes Content format: Markdown version of the public page. Content reviewed: 2026-10-11 # Construction estimating mistakes: checks before you commit An estimate can add up correctly and still price the wrong work. Check its scope, quantities, rates and delivery assumptions before relying on the total. by [Jack Butler-Kettle]() · About 5 min readShare ## What does this mean for me? Missing work, duplicated allowances or unsuitable rates can leave your tender underpriced or your budget unreliable. Correct arithmetic alone does not make an estimate dependable. Once a price is accepted, finding an estimating error does not itself let you change the contract price. Establish the cause and commercial effect before committing. ## What do I need to do? 1. ### 1. Check the document issue first List the drawings, revisions, specifications and tender clarifications used. Compare that list with the latest agreed information before checking individual rates. A later drawing may add work, remove work or change its description. Repricing an old quantity does not deal with a changed design. Where information conflicts, record a query and the working assumption. Do not silently choose whichever document produces the lower total. 2. ### 2. Look for gaps between work packages Check who has included access, protection, temporary works, testing, waste, making good and interfaces between trades. Include only what the actual project requires. A supplier quotation might cover supply but exclude installation, delivery or handling. Compare its scope with the item it is meant to price. Our [Quantity take-off and bill of quantities preparation]() can establish the measured scope when missing or unreliable quantities prevent a useful price check. 3. ### 3. Separate quantities from pricing assumptions Check units, measurement rules and the quantity source. Then examine what each rate includes, its date and whether it suits the proposed method and location. Do not apply a rate per metre to square metres. Check whether labour, materials, plant and waste are already included before adding them separately. The [RICS New Rules of Measurement]() distinguish cost planning from detailed measurement. Agree the method and document purpose before comparing totals. For a contractor preparing a bid, build the price from quantities, resource rates and the planned method. Check supplier quotes for scope, validity and delivery. Use an explicit sequence: define scope, measure quantities, build rates, add project preliminaries, apply overheads and profit, then assess risk. Reconcile the result before submission. Check [markup versus margin]() before applying a percentage. A 20% markup is not a 20% margin on the selling price. 4. ### 4. Reconcile allowances and the programme Check the assumed duration against time-related costs, such as agreed site management and hired facilities. A longer programme can change cost without changing measured quantities. Record how preliminaries, overheads, profit, inflation and risk are treated. Replacing an allowance with a firm quotation should remove the superseded allowance. A contingency does not explain a known omission. Identify the omitted work and its basis before deciding what separate uncertainty remains. A spreadsheet or estimating application can organise the calculation but cannot decide whether the enquiry is complete. Record outstanding queries and approved pricing assumptions. Use [Main-contract tender pricing]() or [Subcontract tender pricing]() for support with an incoming enquiry. Scroll across to read all columns. Estimate checks and the decision they support | Check | Question to resolve | | --- | --- | | Document issue | Does this price the current design and specification? | | Package interfaces | Who has allowed for each necessary item? | | Quantity and unit | Can the measurement be traced and checked? | | Rate inclusions | Is anything omitted or counted twice? | | Programme | Do time-related allowances match the intended duration? | | Allowances | What remains uncertain after firm prices replace estimates? | 5. ### 5. Keep a clear record of corrections Show the original amount, proposed adjustment, reason, source and status. Distinguish confirmed changes from estimates awaiting a quotation or decision. Reconcile the revised total back to the original. This helps the person approving the price understand whether the movement reflects scope, rates or a correction. If a tender has already been submitted or accepted, a revised estimate does not itself change the agreed contract price. Check the contractual position separately. 6. ### 6. Match the support to the decision For an affordability decision or design comparison, [Construction estimating and cost planning]() can produce or review a budget on a stated basis. For a price you intend to submit, [Main-contract tender pricing]() covers the bid build-up, quotations, delivery assumptions and qualifications. If an estimate already exists, a [fixed-fee tender estimate check]() can examine a defined document set. A full remeasurement is separately scoped. When requesting a quote, identify the work packages, drawing issue, existing estimate and submission date. This lets us define the output and confirm capacity. ## Sources 1. [RICS NRM: New Rules of Measurement](). RICS. ### Estimate review checklist Use an independent check where possible. Record the source, issue and action for each review point instead of marking a box without evidence. [Download blank Excel workbook]() Free blank template for your own project. The completed example is shown below. No email address required. View the completed example Completed fictional example Westhaven refurbishment · 14 October 2026 · Version 1.0 #### Estimate review checklist Scroll across if needed to read the whole record. A dash means no value has been entered. Estimate review checklist: completed fictional example | Review area | Check performed | Finding | Action / owner | Status | | --- | --- | --- | --- | --- | | Scope | Compare estimate with drawing register C | Services shown but no priced item | Estimator to add services allowance | Open | | Quantities | Check partition take-off M-01/M-02 | 80 m² reconciles to measured sheets | Retain checked take-off | Complete | | Rates | Review supplier quotation dates | Board quote expires 30 Oct | Reconfirm before order | Open | | Risk and tax | Review risk register and tax basis | Ground risk separate; VAT excluded | Confirm funding budget includes applicable VAT | Open | The completed example uses fictional people, events and records. Replace it with your own verified information and preserve supporting evidence. [Browse the Library]()