The Bill of Quantities: What to Check Section by Section

A bill of quantities is where scope becomes money. What each section covers, what drives it, and the specific checks that catch pricing problems early.

A bill of quantities lists every item of work with its measured quantity so that contractors price the same scope in the same order. For an owner it is the most useful document in a tender, because it shows where the money is and lets you compare bids line by line. This walks through the sections and what to look for in each.

What this number does and does not include

This covers the structure of a bill for a typical building and the checks an owner or their cost consultant should apply. It does not provide rates, because every rate depends on specification, quantity, location and the market at the time of pricing. It also assumes the bill was prepared from a substantially complete design, since a bill measured from an unfinished set carries its incompleteness into every section.

Preliminaries and general requirements

The cost of running the site rather than building: management, establishment, plant, access, temporary services, safety and commissioning. It is the section where bids differ most, because it reflects each contractor own organisation and assumed programme.

• Pushes it up: A long programme, a constrained site and requirements you have imposed without describing.
• Brings it down: A short programme, clear site information and a well sequenced design.
• How to control it: Require it split into a fixed element and a monthly time-related rate, and compare it as a percentage of each bid.

Substructure and earthworks

Excavation, disposal, foundations, ground slabs, retaining, waterproofing and backfill. Quantities here depend on the geotechnical report, so this is the section most exposed to what the ground turns out to be.

• Pushes it up: A basement, poor bearing capacity, rock, groundwater and neighbouring structures close to the boundary.
• Brings it down: Shallow foundations on competent ground with space to work.
• How to control it: Check that the measured quantities match the foundation design in the geotechnical recommendation, and that temporary works are priced rather than assumed.

Structural frame and slabs

Concrete, reinforcement, formwork and any structural steel. It is usually the largest single measured section and it is driven by the structural grid, the span and the floor thickness, which are design decisions rather than site conditions.

• Pushes it up: Long spans, irregular geometry, thick slabs, heavy reinforcement and transfer structures.
• Brings it down: A regular grid, repeated floor plates and a design coordinated with standard formwork sizes.
• How to control it: Compare reinforcement tonnage per square metre between bids, since a wide difference usually signals a measurement or design misunderstanding.

Envelope and external walls

Blockwork or cladding, insulation, windows, doors, glazing and external finishes. This section carries the thermal performance the building code requires and it also determines much of the maintenance liability you will live with.

• Pushes it up: A large facade area relative to floor area, complex detailing, imported systems and extensive glazing.
• Brings it down: A compact form, repeated window sizes and locally available materials.
• How to control it: Check that the specified insulation and glazing performance appears in the measured items, not only in the specification text.

Internal finishes

Plaster, screeds, tiling, painting, ceilings, joinery, sanitaryware and ironmongery. This is what a buyer or tenant actually experiences, and it is the section most often reduced when a tender comes in high.

• Pushes it up: A high specification, many small wet areas, bespoke joinery and a large number of unit types.
• Brings it down: Repeated unit layouts, standard products and dimensions coordinated to material sizes.
• How to control it: Cross-check every finish in the bill against the signed finishes schedule, and query any item described only as an allowance.

Mechanical, electrical and plumbing

Cooling, ventilation, electrical distribution, water supply, drainage, lifts, fire detection and suppression. It is frequently priced by subcontractors, so the quality of those quotations decides whether the section is realistic.

• Pushes it up: High cooling loads, complex distribution, generator provision, lifts and extensive fire systems.
• Brings it down: A simple services strategy, a compact plan and equipment selected from locally supported ranges.
• How to control it: Ask which packages are firmly quoted and which are estimated, and confirm that life safety provisions in the bill match the approved design.

External works and site development

Boundary walls, gates, paving, parking, drainage, landscaping, irrigation, external lighting and the connections across the site. It sits at the end of the bill and at the end of the project, which is why it is so often the section that is thin or absent.

• Pushes it up: A large plot relative to the building, extensive landscaping, level changes and long service runs.
• Brings it down: A compact site, minimal landscaping and services close to the building.
• How to control it: Confirm it is actually measured rather than carried as a lump allowance, because this is the commonest omission in a low bid.

Provisional sums and dayworks

Amounts included for work that cannot yet be defined, plus rates for work carried out on a time and materials basis. Legitimate in limited quantity, and a warning sign in volume, because they sit outside competitive pricing.

• Pushes it up: An incomplete design, unresolved specialist packages and unknown ground or existing conditions.
• Brings it down: A complete tender set with specialist design resolved before pricing.
• How to control it: List every provisional sum with a reason and a cap, and track how much of the contract sum sits outside firm pricing.

Costs that never appear on the first page

• Items measured as an allowance rather than a quantity, which are estimates wearing a bill format.
• Attendance on subcontractors, applied as a percentage that is easy to overlook.
• Builders work in connection with services, which sits between two trades and is often thin.
• Testing and commissioning that appears in the specification but not in the bill.
• Handover documentation, as-built records and operating manuals with no priced item attached.
• Rate adjustment provisions on unfixed materials that change the account after award.

Keeping the budget honest

Compare bids section by section, not by total, and calculate each section as a percentage of the bid. Where a bidder is well below the others on one section, assume a difference in understanding rather than in efficiency until they explain it. A section that is unusually low in the winning bid is the section most likely to generate a claim once work reaches it.

• Before issue, checking the bill against the drawings and the specification for consistency.
• At tender analysis, comparing each section as a percentage between bidders.
• Before award, confirming that provisional sums and allowances are at a level you accepted.
• At each valuation, comparing measured progress against the bill sections.
• At final account, reconciling the outturn against the original bill section by section.

Domira designs, builds and manages projects across Saudi Arabia for owners who are based abroad: land appraisal, feasibility, design, construction, handover and asset management under one accountable contract. Send us the plot or the brief and Domira will put the numbers in front of you before you commit.