The six normalisation steps
1. Bring to the same VAT basis. Excluding or including, without mixing. The rate difference between new build and eligible refurbishment is enough on its own to reverse a ranking.
2. Bring to the same area. Check which area each offer uses as denominator, and convert. The common Belgian convention is gross area, but it is not universal.
3. Bring to the same stage. Establish the list of trades included in each offer rather than accepting the name of the stage. The part-finished shell in particular has no stable definition.
4. Reinstate the excluded items. Identify what each offer leaves out, notably kitchen, connections, fees and external works, then add the same provision to both.
5. Check the ground assumptions. An offer assuming shallow foundations and one that has allowed for remedial work are not comparable until ground investigation settles the point.
6. Check the treatment of price revision. A fixed offer and a revisable offer do not commit to the same final sum.
The normalisation table
| Element to check | Offer A | Offer B |
|---|---|---|
| VAT basis | ||
| Denominator area and method | ||
| Stage and list of trades | ||
| Kitchen included | ||
| Connections included | ||
| Fees included | ||
| External works included | ||
| Foundation assumptions | ||
| Price revision | ||
| Construction period |
Once that table is filled, the real gap appears, and it is often very different from the one displayed.
Questions to ask before comparing
Four questions secure the essentials, and they are legitimate. A sound contractor answers them without difficulty.
On what area is the price per m² calculated. Ask for the method, not merely the number.
Which trades are included and which are not. A list, not a heading.
What assumptions were made on ground and connections. That is where later variations lodge.
Is the price fixed or revisable, and under what formula. This is covered in the article on price revision.
A serious contractor answers those four questions without difficulty. Reluctance to answer is itself information.
Signals that warrant attention
Five situations deserve particular vigilance. Each signals a difference of scope rather than of price.
A price markedly below the others with no explanation of scope. The gap rarely comes from better organisation.
A vague description of services items. Ventilation, heating and electrics are the trades where specification gaps hide best.
No mention of the applicable VAT rate or of its conditions.
No contingency item on a project touching existing fabric.
A construction period notably shorter than the others without justification of method, since it is generally paid for elsewhere.
What a benchmark will never tell you
A limit worth keeping in mind.
The price per m² says nothing about quality of execution, the contractor's financial standing, actual availability or the clarity of contract documents. Those four elements are verified by means other than the quote.
Two normalised offers a few per cent apart are not decided on price. They are decided on references, precision of specification and warranties.
What this means for an estimate
Three rules.
Normalise before concluding, always, including where the displayed gap looks decisive.
Document the normalisation. The table also justifies the choice to a third party, or recalls it in six months.
Treat the residual gap as a fact, not a verdict. It indicates where the next questions belong.
This article reflects professional practice at the date of checking and serves as orientation. It does not constitute legal advice and does not replace assessment of the individual case.