Structural and general building work in Saint-Jean-Cap-Ferrat

The shoreline properties of the peninsula are overwhelmingly built on slopes: retaining walls, successive terraces, stepped access down to the sea. The consequence is structural before it is scenic — a terrace is never dealt with independently of the wall that carries it, and the condition of old retaining works is the recurrent point of vigilance on this kind of ground. That is where a survey begins, not at the residence.

Salt does not stop at the render. Exposed on three sides, the peninsula takes a salt deposit on almost every orientation, and a structure ages here differently from one a few kilometres back from the coast. What chlorides attack is the steel: they migrate through the concrete, reach the reinforcement, make it swell, and the cover eventually spalls — the disorder reads at the surface long after it began in depth. A ring beam, a lintel, an old terrace slab are therefore sounded before they are clad. Cover depth is measured; it is not assumed.

The commune falls within seismic zone 4 under decree no. 2010-1255. For a villa or a house — importance category II — the order of 22 October 2010 first lays down a rule that holds for all works, whatever they may be: they must not increase the building’s vulnerability to earthquake. Beyond that, two thresholds trigger full application of the design standard — increasing the initial floor area by more than 30 %, or removing more than 30 % of the floors at any one level. The reference acceleration retained in zone 4 is 0.96 m/s².

Those thresholds change the nature of a project more than its apparent scale. Opening a level up widely, taking out a floor to gain a double height: these are gestures that tip a work from one regime into the other, and they are settled at the study stage, not in front of the wall. The Alpes-Maritimes prefecture, moreover, records no approved risk prevention plan on the commune — so no regulatory zoning will say in advance what a given piece of ground will bear. What is known of the soil here has to be gone and fetched: boreholes, geotechnical study, examination of neighbouring works.

The peninsula is served by a dead-end road network: you enter and leave through the same neck, with no bypass. The lanes serving the properties are narrow, winding and lined with boundary walls; passing a heavy vehicle and turning it round are the hard points of any logistics. As the plots are walled and planted, the approach of a lifting appliance is prepared from the road, with no possibility of encroaching on neighbouring land. This is not settled on the day: it is decided at the survey.

A sound structure is what permits everything else. On the Cap it decides whether a complete renovation can reopen the volumes towards the sea, whether bespoke finishes and interiors will find stable substrates, and whether an extension or a park fit-out can be considered without first making good the terraces. Our craft in Saint-Jean-Cap-Ferrat reads in that order.