radier
Page approvedn. m. · mat foundation (US) · raft foundation (UK)
Definition
Dalle épaisse en béton armé qui occupe toute ou partie de l'emprise du bâtiment et répartit sa charge sur le sol. On l'emploie quand le sol porte peu, ou quand les semelles seraient si proches qu'elles se toucheraient.
A thick reinforced-concrete slab that covers all or part of the building's footprint and spreads its load over the ground. It is used when the soil has a low bearing capacity, or when footings would be so close together that they would touch.
Diagram
Example sentences
Written (email, official document)
FRBonjour, le sol est peu porteur : nous proposons un radier général plutôt que des semelles.
ENHello, the soil has a low bearing capacity: we propose a raft foundation rather than footings.
Spoken (standard)
FROn coule le radier en deux fois, avec un joint de reprise au milieu.
ENWe're pouring the raft in two stages, with a construction joint in the middle.
Spoken (informal)
FRAvec ce terrain, c'est radier ou rien.
ENWith this ground, it's a raft or nothing.
Nuances and pitfalls
Two words depending on the country. In the US, say mat foundation (or mat slab); in the UK, raft foundation.
Not a floor slab. A radier is part of the foundations and carries the building; a slab on grade (dallage) carries only its own weight and the use loads.
Another meaning. In civil engineering, radier also names the bed of a hydraulic structure (canal, bridge, ford), in English invert or apron: nothing to do with a building foundation.
Related terms
fondationssemellebéton de propretédalle sur terre-pleinarmatureRegulatory and standard references
Legislation in force may differ from what is shown here.
Validation
- French term, register, FR sentences : ✓ validated
- US/UK equivalents and EN sentences : ✓ validated
- Diagram : ✓ validated
Reviewed by Raphaël B. · 3 Oct 2026
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