A BOQ can look complete and still carry serious tender risk. The problem is rarely a simple addition error. It is usually a quantity that was measured to the wrong boundary, a drawing revision that did not make it into the take-off, or a scope item sitting between trades with no clear owner. Knowing how to review BOQ quantities is how a builder turns a take-off into a price they can stand behind.
For residential work, the review needs to be fast enough to protect bid time but disciplined enough to expose the items that can erode margin after award. The aim is not to remeasure every line from scratch. It is to test the BOQ’s logic, confirm the high-value and high-risk quantities, and make the assumptions visible before subcontractor pricing goes out.
Start with the document set, not the workbook
A quantity review begins by confirming what the BOQ was measured from. Check the drawing register, revision dates and issue status against the architectural, structural, hydraulic, electrical, BASIX or NatHERS documentation, engineering details and any authority conditions. A BOQ based on a superseded floor plan can be internally accurate but commercially useless.
Put the current document issue at the top of the review file. If information is missing, record it as a provisional allowance or an explicit exclusion rather than allowing an estimator to fill the gap with an unstated assumption. DA-stage documentation often leaves joinery, external works, retaining, services routes and construction details unresolved. That is normal. Treating those items as measured scope is where tender risk starts.
Also check that the project description is right. A duplex with separate services, fire separation requirements and constrained access is not simply two houses. The BOQ structure should reflect the way the job will be built, packaged and programmed.
Review BOQ quantities in the order risk appears
Do not begin with low-value lines such as door stops or toilet roll holders. Start where a small measuring error creates a large cost movement, or where the documentation is most likely to be incomplete.
Test the geometry of the building
Check the basic geometry before reviewing individual trade quantities. Compare floor areas, building perimeter, wall lengths, roof footprint, storey heights and site levels across plans, elevations and sections. These are the control totals that tell you whether the measured model makes sense.
For example, an external wall area should broadly reconcile with the building perimeter and height, less openings. If cladding area is materially different from the elevation take-off, investigate whether gable ends, parapets, raked ceilings or attached garages have been omitted or counted twice. The same approach applies to internal linings, painting and insulation.
Use gross quantities first, then test the deductions. Over-deducting windows from framing, cladding, plasterboard or painting is a common source of optimistic quantities. Some trades price openings differently, particularly where reveals, flashings, trims, lintels and jamb treatment remain. The BOQ needs a consistent measurement rule that matches how the package will be priced.
Reconcile plans, sections and details
Plans show extent. Sections and details often show cost. Review every area where the section changes the assumption made from the plan: slab steps, dropped edge beams, retaining walls, ceiling bulkheads, raked roofs, balcony waterproofing returns, fire-rated junctions and level changes.
A good check is to mark each detail reference on the plan and confirm that it has landed in the relevant trade section of the BOQ. If a retaining detail exists but no excavation, spoil removal, drainage, membrane, backfill or engineering allowance appears, the quantity may be technically correct for one line but incomplete as a scope package.
This matters particularly on sloping sites and regional jobs where access, spoil handling and subcontractor availability can move the real delivered cost well beyond a generic allowance.
Follow quantities across trade boundaries
The most expensive misses tend to occur at interfaces. Review the BOQ by asking who owns each transition, not just whether a quantity exists. For every major element, follow the work from demolition or earthworks through structure, enclosure, services and finishes.
Pay close attention to the following interfaces:
- excavation, rock allowance, piers, slab penetrations and stormwater;
- framing, steel, trusses, bracing, tie-downs and structural connection hardware;
- roofing, sarking, insulation, flashings, gutters, downpipes and overflow provisions;
- wet-area waterproofing, screeds, tiling returns, niches, grates and shower screens;
- external works, including driveways, paths, drainage, fencing, retaining and landscaping interfaces.
A BOQ does not need to prescribe every subcontractor’s methodology. It does need to make clear whether the quantity is measured, provisional or excluded. If the scope is left ambiguous, every trade will make its own assumption and the tender comparison will be distorted.
Check the units, waste and measurement rules
A quantity can be correct numerically and still be wrong for procurement. Check that the unit suits the way the trade buys and installs the work. Concrete may be measured in cubic metres, but pump access, minimum loads, finishing complexity and reinforcement congestion affect the package cost. Timber flooring in square metres needs an allowance for cuts, waste, pattern direction and stock lengths. Tiles need separate logic for floors, walls, skirtings, niches and external applications.
Do not hide all waste inside rates without noting the rule. For materials with meaningful yield loss, either include an appropriate waste factor in the quantity or state that the rate includes it. The correct treatment depends on how your rate cards and subcontractor pricing packs are set up. Consistency is more valuable than a false impression of precision.
The same applies to openings and deductions. Establish whether door and window openings are deducted from linings, paint, insulation and cladding, then apply the rule consistently. A mixed approach makes quantities impossible to audit and gives subcontractors room to price around uncertainty.
Separate measured scope from provisional allowances
A clean BOQ distinguishes what can be measured from what cannot yet be defined. Measured scope should have a traceable drawing basis, unit, quantity and trade allocation. Provisional allowances should identify the known unknown, the pricing basis and the trigger for confirmation.
Examples include rock excavation where no geotechnical report is available, authority fees not yet confirmed, service upgrades, detailed landscaping, custom joinery pending selection, or site remediation. Do not convert these into precise-looking quantities simply because the workbook requires a line item.
The commercial benefit is twofold. First, the tender total is more honest about where movement may occur. Second, the builder can direct effort to the allowances that matter before contract, rather than discovering them during construction when leverage is gone.
Use subcontractor pricing to validate, not replace, the BOQ
Issue trade packages with enough measurement detail for subcontractors to price consistently, but retain the BOQ as the control document. Ask trades to identify omissions, qualifications and quantity departures against the issued pack. Their response is valuable market intelligence, especially where local labour capacity, freight, access or programme constraints affect regional pricing.
When quotes return, do not compare only the bottom line. Compare their quantified scope against the BOQ. If one roofer has included more roof area, or one plumber has allowed for external sewer and another has not, resolve the variance before selecting a number. A low quote is not a saving if it relies on an unpriced scope gap.
This is also where rate cards should be challenged. A rate card gives a fast, consistent pricing baseline across NSW, QLD, VIC and regional markets, but it cannot see a difficult driveway, a tight inner-city laydown area or a local subcontractor shortage. Use current trade feedback to test the rate, then document the adjustment.
Build a review trail that the delivery team can use
A reviewed BOQ should show more than final quantities. Record revisions, assumptions, exclusions, provisional allowances and unresolved queries in the workbook or accompanying cost estimate report. This creates a usable handover from pre-construction to the site team.
Keep the review focused on material movements. If a quantity changes, note why: revised plan, section check, supplier information, structural detail or trade clarification. That trail helps when a client variation, consultant update or value engineering option is assessed later. It also stops the team re-opening the same question every time the estimate is updated.
Make the final check against programme and buildability
Before issuing a tender, test whether the BOQ reflects the intended construction programme. Temporary works, scaffold duration, protection, access equipment, supervision, preliminaries and staging can be missed when quantities are reviewed only by trade. A three-storey or constrained-site job may have reasonable material quantities but very different labour and handling requirements.
Ask one final practical question: could a site supervisor use this BOQ to understand what has been allowed? If the answer is no, the estimate may be too compressed, too assumption-heavy or poorly structured for delivery.
A fast estimating workflow does not mean accepting untested quantities. EstiFlow’s editable BOQ workbook, subcontractor pricing packs and cost report are designed to make this review visible and workable before tender. Compare the result against a past priced job, challenge the major variances, and resolve the scope that can hurt you most. That is where a quantity review earns its time.