Quote for new house construction: how to analyse it
A new-build construction quote is never a simple tariff grid: it is the contractual basis of your future site, the reference document in case of dispute, and the frozen snapshot of what you are buying exactly. Its structure, its level of detail and its explicit exclusions determine the scale of potential extras you will discover during execution. A sloppy quote can generate 10 to 25% in extra costs; a solid quote protects you from bad surprises. This page gives you the criteria to distinguish a rigorous detailed quote from a vague one, to compare house quotes on homogeneous bases, and to read a bill of quantities without falling into traps.
Why a detailed quote protects you legally
In Belgian construction law, the quote has a dual function: commercial and contractual. Commercially, it allows you to compare several offers and choose. Contractually, once signed, it becomes the main annex of the construction contract, generally integrated into the specifications. Everything in it is owed; everything not in it is optional or excluded.
It is this contractual dimension that makes the quote’s rigour crucial. On an 18-month site, the contractor may be tempted to present as “extras” services you thought included. If the quote is precise, you win the debate; if it is vague, the contractor imposes their reading. See also new-build house builder for choosing the provider.
Structuring items of a serious quote
A complete detailed quote for new house construction must contain at least 8 major categories, each subdivided:
1. Preparatory works and land: soil study, earthworks (excavation, fill, levels), soil evacuation, provisional services.
2. Foundations and structure: foundation type (strip, raft), reinforced concrete, slabs, masonry elevation, perimeter insulation, basement caisson water-tightness.
3. Weather-tight shell: load-bearing wall elevation (bricks, blocks), intermediate floors, roof (frame + covering + zinc work), exterior carpentry (frames, glazing, sills, breast walls), garage doors.
4. Second fix: interior partitions, screeds, ceilings, wall and ceiling finishes, interior painting, stairs, interior carpentry (doors, skirtings), floor coverings per room.
5. Fluid techniques: sanitary plumbing (cold/hot water, drainage, sewer connection), heating (production + emission + control), ventilation (system C/D), rainwater.
6. Electrical techniques: panel, wiring per RGIE, sockets and lighting points per room, optional home automation, video door entry.
7. Equipment and sanitary: equipped kitchen (often optional), bathroom (basin, shower/bath, WC), optional reduced-mobility equipment.
8. Exterior fitting: terrace, access driveway, fencing, lawn, planting, garden shed.
For each line, demand: technical description (material, brand, model, series), quantity (m², ml, pieces), unit price excl. VAT, total price excl. VAT, applicable VAT, price incl. VAT.
The bill of quantities: what distinguishes a serious quote
A bill of quantities is the technical document that details quantitatively each item. Without precise quantities, the quote is only a potentially adjustable global lump sum. With quantities, every modification during the site can be priced transparently.
Typical bill of quantities for a 150 m² habitable house: 300 to 600 line items, occupying 15 to 40 pages. A quote fitting on 3 pages with “shell lump-sum: €95,000” is a major alarm signal: impossible to verify what is included, impossible to price amendments, impossible to challenge in case of dispute.
For turnkey contracts, demand the detailed specifications signed jointly with the preliminary agreement. This document describes room by room and lot by lot the exact services: boiler brand, tile model, insulation thickness, paint nature. It is the cornerstone of legal security in new-build construction.
Comparing several quotes on homogeneous bases
To compare house quotes effectively, follow the cross-table method:
- List horizontally all items present in the most detailed quote.
- List vertically each contractor from whom you received a quote.
- For each cell, indicate the amount excl. VAT and, if absent, signal “not included”.
- Total by item: a quote that seems expensive can be cheaper in homogeneous totalisation.
- Identify critical exclusions: earthworks at €8,500 missing from a quote becomes a trap.
Based on our new house price per m², a gap of more than 15% between two quotes for equivalent services should alert you: either one is undervalued (and the contractor will catch up on amendments), or the other is overvalued (and you pay the margin).
Case study: 28% gap corrected after audit
A case audited by the firm in 2025: family hesitating between three contractors for a 165 m² villa in Walloon Brabant.
- Company A: 4-page quote, total €285,000 excl. VAT.
- Company B: 18-page quote, total €312,000 excl. VAT.
- Company C: 32-page quote with full bill of quantities, total €328,000 excl. VAT.
At first sight, A is €43,000 cheaper than C. After detailed audit item by item:
- A excludes: earthworks (€9,500), screed (€6,800), interior paint (€5,400), kitchen (€16,000), terrace (€12,000).
- B includes everything except kitchen and terrace.
- C includes everything.
Homogeneous recalculation: A becomes €334,700, B €340,000, C €328,000. C is actually the cheapest and the most transparent. Without this audit, the family would have signed A thinking they were saving, then suffered €50,000 in extras during the site.
Pitfalls in quote analysis
- Reading only the total amount: 90% of risk is in detail.
- Accepting “lump sum” without quantities: impossible to challenge an amendment.
- Neglecting explicit exclusions: earthworks, screed, connections, final paint are often outside scope.
- Confusing excl. VAT and incl. VAT: depending on 6% or 21% VAT, the gap can reach 15%. See 6% VAT conditions.
- Ignoring indexation clauses: a Breyne Law contract may provide a revision according to the ABEX index — check the cap.
- Forgetting certificates and warranties: mandatory Peeters ten-year certificate, architect professional liability, site CAR.
Securing your project before signing
A professional quote audit typically costs €400 to €900 and allows identifying on average €15,000 to €50,000 in extra costs or hidden exclusions. It is by far the best investment/saving ratio of a construction project. The firm Mon Etat Des Lieux offers a Breyne Law support including critical reading of quotes, specifications analysis and verification of contract clauses. For the rest of the journey, see provisional reception expert. Request a free quote within 24 hours. Also consult new house price and new-build notary fees for the global budget.