The building permit is a document most owners open once — at the signing of the preliminary sales agreement — and never pull out again. That is precisely what makes the fortune of land surveyors and the ruin of owners who discover, three years after delivery, that their carport overhangs by 80 cm into the setback zone or that the ridge height exceeds the filed plan by 25 cm. On 80 construction sites I have audited, 12 showed a permit non-compliance to varying degrees. A non-compliance that costs 3,000 € to settle during construction easily costs 35,000 € after reception, court and regularisation fees included. Here are the three key moments to check it.
First check: at the contractor’s signing
Before signing the construction contract, demand the full copy of the building permit with all annexes: plans, sections, elevations, technical description, special planning conditions, photo file of existing if renovation. Compare line by line with the contract proposed by the contractor. Any divergence — ridge height, roofing material, opening positions, façade finish — must be noted and accepted in writing in the contract.
The frequent divergences I see on turnkey contracts:
- Roofing material: concrete tile instead of required terracotta tile
- Frame colour: white instead of required anthracite grey
- Cladding: composite instead of required wood
- Roof slope: changed from 35° to 30° without planning agreement
A planning addendum costs about 1,500 € to file during construction. An unfavourable final inspection report after reception costs ten times more, with no guarantee of obtaining regularisation.
Second check: at the weather-tight shell stage
When the roof is on and the frames are placed, the external envelope is fixed. This is the right time to check on site:
- Actual ridge height vs permit plan (surveyor measurement)
- Implantation relative to plot boundaries (setbacks, party wall)
- Highway setback (non-aedificandi zone)
- Visible materials (cladding, roofing, frames)
- Projections (balconies, bay windows, roof overhangs)
A surveyor returns for 350 € for an interim inspection at this stage. It’s the best possible expenditure — it costs 100 times less than a post-reception regularisation. Of the 80 construction sites I have supported, 5 triggered this interim inspection: 4 revealed minor discrepancies corrected within weeks, 1 avoided a partial demolition that would have cost 28,000 €.
Third check: at reception
Strictly demand the municipal planning final inspection report. This document is issued by the municipal planning service after on-site verification and certifies that the construction is compliant with the granted permit. Without it, you buy the administrative risk — a risk that can block a future resale, lose energy subsidies, and prevent final reception within the meaning of the Breyne Law.
At the slightest detected divergence:
- Refuse reception or sign with explicit reservation
- Demand a compliance bringing by planning addendum
- Condition the release of the 5% retention on the production of the inspection report
- Photographically document each divergence
Post-reception regularisation goes through a modifying permit file, 18 months of administrative procedure and 3,000 to 6,000 € in lawyer fees for legal coordination. Without guarantee of obtaining retroactive authorisation — if the municipality refuses, partial demolition may be ordered.
Mons 2025 case: disputed ridge height
A client from Mons contacted me in March 2025 after receiving a municipal formal notice: her roof exceeded the permit’s authorised height by 32 cm. The builder denied modifying the plans. Our surveyor’s inspection confirmed the deviation. Regularisation by modifying permit took 11 months and cost 4,200 € — fully financed by the builder after formal notice and adversarial expertise, but without the third-party expertise, my client would have paid alone.
Pitfalls to avoid
- Don’t sign a contract without having the permit in hand and read in full
- Beware of mentions “according to architect’s plans” without an initialled annex
- Check the special conditions of the permit (materials, plantings, rainwater)
- Request the planning inspection systematically, even if the contractor doesn’t mention it
- Keep the original permit with your owner’s file (perpetual duration)
For official planning procedures in Wallonia, see urbanisme.wallonie.be.
What next?
If you have any doubt about your site’s permit compliance, bring in a third-party expert before signing the reception minutes. My firm offers a construction audit that includes planning verification, or a Breyne Law support covering surveyor coordination.