This is mandatory. According to the Labour and Housing Code, article L111-13: “Every builder of a structure is fully responsible, towards the owner or acquirer of the structure, for damages, even those resulting from defects in the land itself, which compromise the solidity of the structure or which, affecting one of the founding components or material components, make it unfit for use.
This responsibility is absolved if the builder proves that the damages were caused by an external cause.”
Structural damage warranty
This comes into effect at the end of a period of one year which covers the guarantee of full completion.