A residential bill of quantities, or BOQ, is a line-by-line list of every piece of work needed to build a home, giving every contractor the same basis to price from. It sharpens tendering, locks down your budget and gives everyone involved a shared language for what is actually being built. A quantity surveyor usually prepares it once drawings are ready, right before tender stage.
TL;DR:
- Wait for complete architectural and structural drawings before commissioning a firm BOQ; earlier approximate quantities carry more pricing risk for every contractor.
- Check preliminaries and provisional sums closely, because vague scopes, understated setup costs, and missing waste allowances can conceal budget overruns during tender review.
- Require each contractor to price every original BOQ line, then compare unusual rates, omissions, and written clarifications before signing.
- Digital takeoff can extract quantities from a 3D model, but a quantity surveyor must verify them, apply local rates, and price unmeasurable items.
- Guideline tariffs can place 60% to 70% of quantity surveying fees at tender and BOQ delivery; request a stage by stage fee breakdown.
Table of Contents
- What a bill of quantities covers and why it matters for your build
- The core components of a residential BOQ
- How to prepare a BOQ: take-off, coding and pricing
- A sample BOQ walkthrough for a small residential project
- What to budget for: works costs and quantity surveyor fees
- Common pitfalls and the checks that protect your budget
- Using the BOQ to evaluate tenders and manage your project
- Why I think of the bill of quantities as a project map, not a price list
- How House A-Z keeps your BOQ, budget and contractors in one place
- FAQ
- Sources
What a bill of quantities covers and why it matters for your build
Think of the BOQ as the document that turns a set of drawings into something every builder can price fairly. RICS NRM2 describes its core purpose as providing a uniform basis for measurement, so tenders come back comparable rather than apples-to-oranges guesswork. Once a contract is signed, that same document underpins valuations and keeps change control honest.
There are two flavours worth knowing:
- A firm BOQ is built from complete, detailed drawings and gives precise, binding quantities.
- An approximate BOQ is used earlier, when design information is still incomplete, and carries more pricing risk as a result.
In the project timeline, the BOQ typically arrives once design development is finished and before contractors are invited to tender, slotting neatly between "we know what we want" and "let's find out what it costs."
The core components of a residential BOQ
A well-built BOQ reads like a map of the whole project, broken into sections that each do a distinct job. Recognising these parts helps you spot when something has been glossed over.
- Form of tender: the contractor's formal offer to carry out the works for a stated sum.
- Preliminaries: site setup, management costs and general conditions, split into an information schedule and a pricing schedule.
- Measured works: the detailed, trade-by-trade quantities for everything from groundworks to finishes.
- Provisional sums: priced placeholders for work that cannot yet be fully defined.
- Contractor-designed works: elements the contractor will design and price as a package rather than measure in detail.
- Risks and annexes: contingencies and supporting schedules referenced elsewhere in the tender.
Bills can be organised elementally (by building element, such as roof or frame) or by trade (bricklaying, plumbing, electrics), with a summary page pulling the totals together at the front. Preliminaries and provisional sums deserve extra scrutiny: they are the sections most often under-priced or left vague, and vague pricing here is where budgets quietly unravel later.
How to prepare a BOQ: take-off, coding and pricing
Before any measuring starts, you need complete architectural and structural drawings. Incomplete information is exactly why so many early-stage BOQs end up "approximate" rather than firm, and approximate figures carry more risk for everyone pricing against them.
- Take off quantities from the drawings: lengths for linear work, areas for finishes, volumes for concrete and earthworks.
- Group the measured items by trade or building element so the bill reads logically, from substructure through to finishes.
- Code each item to a recognised standard, such as NRM2, so descriptions and units stay consistent throughout.
- Apply current market unit rates, add a waste allowance where materials are cut or lost on site, and price provisional sums against a defined scope.
- Sum each trade section and roll the totals into a project summary.
Digital quantity take-off and BIM-based tools can speed up this process considerably, extracting quantities straight from a 3D model. NBIMS-US guidance is clear that a quantity surveyor still needs to verify the output, apply location-specific rates and handle items that software cannot measure, like site preliminaries and risk allowances.
Pro Tip: Keep a running log of every assumption behind a rate or allowance; it saves hours when a contractor queries a figure during tender review.
A sample BOQ walkthrough for a small residential project
Seeing how the sections translate into actual line items makes the whole document far less intimidating. Sample priced BOQs show this structure in practice, with each item recorded against a description, unit, quantity, unit rate and extended amount.
For a small house, the elemental breakdown typically runs:
- Foundations and substructure
- Frame and superstructure
- Roof covering and structure
- Windows and external doors
- Internal finishes and fittings
- Mechanical, electrical and plumbing services
A typical line might read: "Concrete to strip foundations, 1:2:4 mix" measured in cubic metres, with a quantity, a unit rate and the resulting amount in the final column, exactly as NRM2 templates set out.
If you want a working template rather than a blank page, our guide to new build material cost estimating walks through how unit rates feed into a realistic project total. When a contractor sends back a priced BOQ, expect every line filled in against your original quantities, not a lump sum with the detail stripped out.
What to budget for: works costs and quantity surveyor fees
The final tender figure is driven as much by the unit rates contractors apply and the size of contingency and provisional sums as by the raw quantities themselves. Get the rates wrong and even a perfectly measured bill will mislead you.
Professional fees follow a similar logic. Guideline tariff documents show quantity surveying fees apportioned across project stages, with a large share by the end of tender stage, tied to preparing and pricing the bill of quantities itself.
- Ask what stages are included in the quoted fee and what happens if the project is delayed.
- Ask whether the BOQ will follow NRM2 or an equivalent recognised standard.
- Ask for the deliverable format upfront, including whether it will be shared as an editable document.
Common pitfalls and the checks that protect your budget
Most budget shocks trace back to the same handful of weak spots: vague provisional sums with no defined scope, missing waste allowances, underpriced preliminaries, or contractor-designed work left undefined until it is too late to negotiate.
- Reconcile every BOQ line against the drawings before you accept a tender.
- Insist that waste allowances are stated explicitly rather than buried in the rate.
- Require provisional sums to carry a written scope and a specific price, not an open-ended figure.
Pro Tip: Scan the elemental summary for any trade that looks unusually cheap or expensive compared with the others; that mismatch is often where a contractor has made an assumption you haven't seen. Our piece on provisional sums sets out four checks worth running on every scoped allowance before you sign anything.
Using the BOQ to evaluate tenders and manage your project
Once priced returns come in, the BOQ becomes your comparison tool, not just a pricing exercise. Line-by-line comparison reveals where one contractor has omitted an item entirely or quoted a rate wildly out of step with the rest.
- Share the same BOQ with every contractor you invite to tender, so the comparison is genuinely like-for-like.
- Gather priced returns and run a bid-level check, flagging unit rates that sit well outside the typical range.
- Capture contractor clarifications and queries formally, before the contract is signed rather than after.
- Use the agreed BOQ as the baseline for interim valuations and for pricing any variations that arise mid-build.
Our guide to bid levelling walks through this comparison process in more depth, and understanding how contract types interact with the BOQ helps you choose the right procurement route from the outset.
Why I think of the bill of quantities as a project map, not a price list
A BOQ is often treated as paperwork to get through before building starts, but it is really the clearest record you will ever have of what you are actually paying for. Two things stand out from working through these documents: provisional sums are where trust breaks down fastest, and an elemental summary tells you more about a contractor's assumptions than any conversation will. Read it that way and it stops being a hurdle and starts being your best early warning system.
— Azai
FAQ
How much does it cost to get a bill of quantities?
Cost depends on the quantity surveyor's fee structure and the project's stage, since guideline tariffs show a large share of total QS fees, often 60 to 70%, apportioned to tender and BOQ delivery. Ask your surveyor for a stage-by-stage fee breakdown before committing, so you know exactly what the quoted figure covers.
How much does a QS charge per hour?
Hourly rates vary by region, experience and project complexity, and guideline tariff documents publish example banded rates rather than a single universal figure. Ask for a written quote tied to your specific project scope rather than relying on a generic hourly figure.
How do I calculate a bill of quantities?
You start with a detailed take-off from complete drawings, measuring lengths, areas and volumes, then group those quantities by trade or element and apply current market unit rates, following NRM2 measurement rules. Waste allowances and provisional sums are added before the trade totals are summed into a project estimate.
What is the difference between a bill of quantities and a bill of materials?
A bill of quantities measures and prices all the work and materials needed to build a project, following recognised measurement rules such as NRM2, while a bill of materials typically lists only the materials and components themselves without pricing the labour or site costs around them. The BOQ is the document used for tendering and valuation on a construction project.
Can software calculate my bill of quantities automatically?
Digital take-off and BIM-based tools can extract quantities automatically from a 3D model, which speeds up the measurement stage considerably. NBIMS-US guidance notes that a quantity surveyor still needs to verify the output and apply local pricing, so automation supports the process rather than replacing professional sign-off.
Sources
- NBIMS‑US V3: Design to quantity take‑off for cost estimating
- 2024 Guideline time charge (Quantity Surveying Profession Act / SACQSP guidance)
- Proposed house of Mnguni priced bill of quantities (sample PDF)
