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Provisional reception of a home extension: the specific features

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By Edouard Hennin, Provisional reception expert Published on 27 May 2026 Updated on 27 May 2026 6 min read

1. Breyne Law and extension: applicability

Unlike new construction where the Breyne Law applies automatically, a home extension falls within its scope only if the works can be assimilated to new construction. In practice, two criteria apply: the cost of the works relative to the value of the existing property, and the VAT regime applied (6% modest housing vs 21%).

Have the applicable regime validated by your notary before signing the contract with the contractor.

2. The junction points: 80% of defects

At provisional reception of an extension, defects almost always concentrate at the old/new junctions: roof waterproofing on the party wall, facade junction, transition slab, rainwater downpipes, expansion joints. Inspect each of these points meticulously.

Other critical areas: electrical panel taken over from the existing structure, earthing, through-ventilation.

3. Guarantees to demand

Even if the Breyne Law does not apply, systematically demand the ten-year liability of the contractor (article 1792 of the Civil Code), valid on the new works AND on their junctions to existing parts.

To secure reception, expert assistance remains valuable — particularly to qualify junction defects, which are often contested by the contractor.

Common questions on reception of an extension

Does the Breyne Law apply to an extension?

Only if the cost of the works exceeds that of the existing property, or if the extension is treated as new construction for VAT purposes. Have your notary validate this.

Which specific points to inspect at reception?

The roof, facade, slab and waterproofing junctions between old and new. That is where 80% of extension defects concentrate.