Asking for prices on a house with an incomplete bill of quantities gets you bids that look comparable and are not. Every contractor prices the list it was given: if a line is missing, it is missing from every bid, and it comes back later, on site, as a variation. This guide walks through what a house bill of quantities should contain, in the order the work happens, and what to check before sending it out.
A bill of quantities is not a budget
The bill of quantities is the list of the works, each with its unit and its quantity — with no prices. The budget is that same list with a unit price on every line. That is why the bill comes first, and why it is what makes bids comparable: every contractor prices the same list.
- Item number — organised by chapter (3.1, 3.2…), so it can be quoted without ambiguity in a bid or in an interim valuation.
- Description — what it is, in what material, where, and what it includes. This is where most site disputes start: “brick wall” says nothing about thickness, brick type, or whether lintels are included.
- Unit — m³, m², m, kg, no., or a lump sum when the work cannot be measured.
- Quantity — measured to a rule, and the same rule from the first line to the last.
- Unit rate and total — blank in the document you send out; filled in by the bidder.
The chapters of a house, in the order the work happens
There is no single mandatory list for private work, but the structure below is what an estimator expects to find. The usual unit is in brackets.
- Site setup and preliminaries — set-up and removal, hoarding, setting out (lump sum or no.).
- Earthworks — stripping (m²), excavation and fill (m³), disposal off site (m³).
- Foundations and structure — concrete (m³), formwork (m²) and reinforcement (kg), split by element: pad footings, ground beams, columns, beams, slabs, stairs.
- Masonry — external and internal walls, split by type and thickness (m²).
- Roof — structure, insulation and covering (m²); gutters, flashings and downpipes (m).
- Waterproofing and insulation — foundations, terraces, façades (m²).
- Wall and ceiling finishes — renders, plaster, tiling, suspended ceilings (m²).
- Floors — screeds and finishes (m²); skirtings (m).
- Windows and metalwork — windows and external doors (no., with sizes in the description); balustrades (m).
- Joinery — internal doors, wardrobes, kitchen units (no.).
- Painting — internal and external (m²).
- Building services — water and drainage, rainwater, electrical, telecoms, gas, ventilation and HVAC, fire safety: pipework and cabling (m), points and equipment (no.). One trade per chapter, whichever the design includes.
- External works — walls, external paving, buried services (m², m, m³).
The lines most often missing
They are almost always the ones that are not drawn, or that fall between two chapters:
- Site setup and safety — hoarding, signage, collective protection.
- Waste management — transport to final destination and its records.
- Trims and edges — sills, thresholds, copings, flashings, joints.
- What ties the services into the structure — chases, penetrations, slab openings.
- Utility connections — water, drainage, electricity and telecoms.
- Final cleaning and as-built drawings.
A missing line does not disappear from the cost of the building. It only disappears from the comparison between bids.
How to check a bill of quantities before sending it out
- Every element drawn has a line. Go through plans, sections and elevations with the bill beside you, chapter by chapter.
- Quantities match the drawings. Floor finish area cannot exceed the floor area; roof area must be consistent with the roof plan and its pitch.
- Units are measurement units, not purchasing units. Concrete in m³, not truckloads; reinforcement in kg, not bars.
- The description says what is included. And refers to the technical specification, where there is one.
- Lump sums are the exception. If work can be measured, measure it; a lump sum cannot be compared between bids.
- There is one measurement rule, and it is written down. What is deducted at openings, what is measured at intersections. In Portugal the usual reference is the LNEC measurement rules — which carry no force of law, which is precisely why the rule used has to be stated.
And if the design is in Revit or IFC
When the house was designed in a BIM model, the quantities can come from the model itself: every line traces back to the elements that produced it, and a design revision is re-measured without starting over. What does not change is everything above — the chapters, the description, the rule. A bill taken from a model still has to be checked; the difference is that you can get from each number back to the element behind it.