Comparing contractor quotes without comparing apples and oranges
Short answer: Quotes are only comparable if they use the same bill of quantities, brands, VAT rate and exclusions. Get at least three quotes and keep a 10 to 20% buffer. Market ranges are wide: Belgian guides put a bathroom at 5,000 to 25,000 euros, so only a site visit and a common basis make the numbers meaningful.
Prices in this article are indicative Belgian market ranges, not Alpha Services Benelux's price list. Your fixed price is in the quote.
Why two quotes rarely match
The price gap between quotes usually comes from what is counted, not from the hourly rate. A fair comparison starts with one shared basis.
Belgian indicative prices are already wide, and sources disagree with each other. That is normal: scope, finishes and VAT basis are not identical everywhere.
| Work | VELUX Belgium | Heylen Vastgoed |
|---|---|---|
| Bathroom (project) | 5,000 – 25,000 euros | 5,000 – 25,000 euros |
| Kitchen (project) | 8,000 – 20,000 euros | 8,000 – 30,000 euros |
| Electrical | 5,000 – 8,000 euros (100 m² home) | 8,000 – 15,000 euros |
| Roof per m² | 30 – 120 euros (covering only) | 60 – 140 euros (excl. insulation) |
Read these as market ranges, not a company price list. Only the amounts on your own quotes reflect your project.
One bill of quantities, identical quantities
Ask every contractor to price the same bill of quantities. Price differences are then real differences, not the result of one contractor counting something another left out.
A bill of quantities is a single list of work items and quantities on which everyone enters unit prices. Anything missing from it comes back later as extra work. Check each item for:
- Quantities and units: m², linear metres, pieces or lump sum.
- Pricing formula: fixed price, price per bill of quantities (you pay the quantities actually carried out) or time and materials.
- Schedule: start date, duration and payment stages.
If a quantity differs between quotes, ask why. Measuring the relevant rooms yourself quickly exposes an estimate that is too low or too high.
Pin down brands, materials and performance
Write down brand, model, thickness and required performance for every item. 'Tiling' or 'insulation' with no further detail leaves room for a cheaper execution.
- Materials: brand, reference, format, colour and finish.
- Performance: for example insulation thickness, tap and appliance type.
- Provisional sums: if a quote carries a 'to be chosen' allowance, ask for the amount per item; otherwise you compare a placeholder with a firm price.
Give each contractor a budget range as well. They can then match the finish level, and the quotes will be less scattered.
Exclusions, coordination, waste, protection and inspections
Ask in writing who carries what. These items often hide in the small print and cause most of the arguments later.
| Item | What to ask |
|---|---|
| Coordination | Who plans and directs the trades (demolition, plumber, electrician, tiler)? Is it included or charged separately? |
| Waste and skip | Is rubble removed and processed, and is that in the price? |
| Protection | Are floors, stairs, doors and furniture covered, and who repairs damage? |
| Inspections | Who orders and pays for, say, the electrical installation inspection (AREI/RGIE) or other mandatory checks? |
| Making good | Plastering, painting and repairs after chasing: included or excluded? |
| Water, power and sanitation on site | Who arranges temporary facilities? |
A quote without an exclusions list is not necessarily incomplete, but you cannot compare it. Ask for one.
VAT at 6% or 21%: compare on the same basis
Always compare quotes at the same VAT rate, with or without VAT. That difference alone can be worth thousands of euros.
According to the Belgian sources consulted, 6% applies to renovation of a dwelling older than 10 years (counted from first occupation) that is mainly used privately, when the contractor invoices the work directly to the end consumer. Materials you buy yourself without installation by the contractor stay at 21%. Since 2022 no certificate is needed: a statement on the invoice is enough, and you are deemed to accept it unless you dispute the invoice in writing within one month. Check the current rules with FPS Finance, because some works (such as swimming pools and fossil-fuel heating) fall outside the reduced rate.
| Rate | VAT | Total |
|---|---|---|
| 6% | 2,400 euros | 42,400 euros |
| 21% | 8,400 euros | 48,400 euros |
A quote shown 'excl. VAT' therefore cannot be compared directly with another shown 'incl. 6% VAT'.
Premiums: work is not automatically subsidised. For Flanders, see vlaanderen.be/mijn-verbouwpremie. In Brussels, Homegrade offers free, non-commercial renovation advice. For Wallonia, we point to energie.wallonie.be. Ask the contractor which certificates and invoice details they can supply for an application.
Fixing extra works in the contract
Agree up front that extra works are offered in writing, with a price and extra time, and carried out only after your approval.
According to Habitos, article 1793 of the Civil Code requires the client's prior written agreement for a fixed-price contract. Watch the general conditions: the FAB (architects') standard specification deviates from this if your contract incorporates it, and allows extra work to be proven by a written order confirmation the contractor sends within three working days; if you do not contest it within three working days of receipt, it counts as accepted. Staying silent can then bind you. Read what you sign.
- Set unit prices at which additional and omitted work will be valued.
- Use time and materials only for small jobs and agree the hourly rate in advance.
- Record every change on a short document: description, price, extra time, signatures of both parties.
- Beware of reservations on quantities: a quote that looks cheaper may pick up extras afterwards.
Budget buffer and how to compare in practice
Keep a reserve of 10 to 20% on top of the quote for the unexpected. Most Belgian sources land in that band, with some variation.
| Source | Buffer |
|---|---|
| VELUX Belgium | 10 – 20% of the total budget |
| Renovatiewerken Antwerpen | 10 – 20% of the renovation budget |
| Bouwprijs.be | at least 10 – 20% |
| Heylen Vastgoed | 10 – 15% on top of the original budget |
An older home or heavier works points to the upper end. Architect fees come on top (7 to 12% of the construction cost according to Bouwprijs.be).
Method:
- Request three quotes on the same bill of quantities, after a site visit.
- Lay them side by side item by item, at the same VAT rate.
- Mark differing quantities, brands and exclusions.
- Have provisional sums priced, or add a margin to them.
- Check company registration (KBO/BCE), insurance and references.
Alpha Services Benelux (active since 2014, own team, not a lead broker) gives a fixed written quote after a site visit. See how we work on renovation and bathroom renovation, or get a first budget idea with the renovation calculator.
Fixed quote after a site visit
Alpha Services Benelux does the work with its own team, active since 2014. VAT BE 0541.320.178.
Request a quoteFrequently asked questions
How many quotes should I ask for?
At least three, on the same bill of quantities and after a site visit. Lay them side by side item by item at the same VAT rate. That shows what really differs: price, quantity, brand or exclusion.
How big a buffer should I add on top of the quote?
Belgian guides mostly suggest 10 to 20%, Heylen Vastgoed 10 to 15%. Aim for the upper end with an older home or heavy works. Architect fees are extra (7 to 12% of the cost according to Bouwprijs.be).
When does 6% VAT apply to a renovation?
According to the sources consulted: the dwelling is older than 10 years, mainly used privately, and the contractor invoices labour and materials directly to you. Materials you buy alone stay at 21%. Check current rules with FPS Finance.
Do extra works have to be agreed in writing?
It is the safe route. According to Habitos, article 1793 of the Civil Code requires prior written agreement under a fixed price. Beware of general conditions, such as the FAB specification (if your contract incorporates it): a written order confirmation from the contractor counts as accepted if you do not contest it within three working days of receipt.
What is the difference between a fixed price and a price per bill of quantities?
With a fixed price the total is set, apart from approved extras. With a bill of quantities you pay the quantities actually carried out at unit prices. Time and materials charges hours plus materials and suits only small or unforeseen jobs.
Sources
- Alles wat u moet weten over de kosten van een huisrenovatie — VELUX België
- Wat kost een woningrenovatie in Vlaanderen? (renovatiekosten 2026) — Heylen Vastgoed
- Renovatie van uw woonst: een schatting van de kosten — Renovatiewerken Antwerpen
- Bouwkosten berekenen 2026 — Bouwprijs.be
- Btw 6% renovatie België: voorwaarden en tarief 2026 — Housing-Service.be
- Renovatie woningen aan 6% btw: niet langer attest nodig — Baker Tilly Belgium
- Hoe weerwerk bieden tegen meerwerk? — Habitos
- Algemeen bestek voor privé-bouwwerken — FAB (Federatie van Architecten)
- Offertes aannemers vergelijken op een correcte wijze — Interieurkabinet
- Meetstaat laten opmaken voor nieuwbouw of renovatie — Unabo
- Mijn VerbouwPremie — Vlaanderen.be
- Homegrade - conseil et accompagnement logement privé à Bruxelles — Homegrade (Région de Bruxelles-Capitale)
- Énergie Wallonie - aides et financements — Service public de Wallonie