Adding a storey to a house in Annecy.

In Annecy, land is extremely scarce and among the most expensive in France. Finding a building plot in the Annecy basin is the exception, and prices per square metre reach record highs, from the historic centre to the lakeshore. In this context, extending a house at ground level is often impossible: no room in the garden, plots already optimised, building footprint allowances used up. Adding a storey then becomes the only realistic option for gaining living space without moving or buying a single square metre of land.

Adding a floor means creating one or more bedrooms, a master suite, a study or a genuine living area by building vertically rather than horizontally. You keep your address, your neighbourhood, the children's school and the lakeside setting, while meeting a need for space that would otherwise force you to move far from the conurbation. In a market as tight as Annecy's, it is also an investment that significantly increases the value of the property: every additional square metre counts double in an area where demand persistently outstrips supply.

Adding a storey is not the only way to gain space, and the right strategy must be chosen for each house. When the plot allows, a ground-level extension (house extension in Annecy) remains a good option. When the volume under the roof already exists, a loft conversion is simpler and less expensive. Adding a storey is the answer when there is neither available land nor a usable loft — a very common situation in Annecy.

Before anything else, one question decides everything: can your house carry one more storey? That is the purpose of the structural study, carried out by a design office before the project. It checks the capacity of the load-bearing walls and foundations to carry the additional loads of a new level: the weight of the structure, the roof covering and the furniture, but also the climatic loads specific to Haute-Savoie.

In the Alpine climate of the Annecy region, the study takes into account snow loads, wind and seismic constraints: Haute-Savoie is classified as a moderate seismicity zone, which imposes precise sizing rules. If the existing structure proves borderline, two solutions are available: reinforce or rework the foundations and load paths, or opt for a timber frame storey, much lighter than a masonry raising and therefore less demanding on the existing building.

This feasibility analysis also determines the choice of technique and the budget. As project manager, we coordinate the structural study, the architectural design and the execution: you get a reliable answer on whether a storey can be added before any commitment, with no nasty surprises during the works. We apply the same rigour to all our renovation and construction services.

Roof raising (partial storey addition) — when the roof pitch limits ceiling height but the structure is sound, the roof can be raised by altering the roof structure: the purlins are lifted, the pitch is changed or a dual-pitch roof is replaced with a higher one to free up living space. It is an ideal intermediate solution when you want to turn a loft that is too low into a genuine floor, without building a full level.

Full timber frame storey addition — this is often the most suitable technique in Annecy. The old roof is removed and a full timber frame storey is built, prefabricated in the workshop and then assembled on site. Its advantages: a lightweight structure (ideal when the foundations cannot carry a heavy masonry load), excellent thermal performance, and above all remarkable speed of construction — once the prefabricated structure is delivered, the new storey is made watertight within a few days.

Masonry storey addition — in concrete block, brick or concrete, it remains possible when the structural study confirms that the foundations and load-bearing walls can take it. Heavier and slower to build, it offers in return perfect continuity with the existing building. The choice between these approaches depends on the structural study, the PLU and your budget: we steer you towards the most appropriate solution, and we always build the new roof structure and roof covering of the storey created, in keeping with the look of Annecy's roofs.

Adding a storey alters the external appearance and creates floor area: it almost always requires a building permit. As soon as the works create more than 20 m² of floor area, or take the total floor area of the house above 150 m², a permit is mandatory — and using an architect becomes a requirement above that threshold. As architect and project manager, Atelier NovAlp prepares and follows this application for you.

In Annecy, the PLU is particularly strict on building heights. Each zone sets a maximum height at the ridge or eaves that an additional storey must not exceed: it is one of the first things we check, as it can determine whether the project is feasible at all. The regulations also govern the appearance of roofs (pitch, materials, colours), integration into the landscape and the neighbourhood — requirements that are stricter near the lake, in the old town and in the conservation area.

In these protected areas, the opinion of the ABF heritage architect (Architecte des Bâtiments de France) may be required, and the requirements on materials and roof coverings become restrictive. We know these rules and we check the PLU, verify the permitted height and put together the complete application: plans, written statement, landscape integration, declarations. You stay in control of your project while we secure the administrative procedures, just as we do for all our projects in Annecy and Haute-Savoie.

The cost of adding a storey generally ranges from €1,800 to €3,000/m² of floor area created. The range depends on several factors: the technique chosen (timber frame is often quicker and lighter, and therefore sometimes more economical than a heavy masonry extension requiring foundation strengthening), how difficult site access is, the scope of the interior fit-out and the level of finish required.

On top of this construction cost come items not to be overlooked: the structural study, project management, scaffolding, removal and complete rebuilding of the roof, and the connections (electricity, plumbing, heating) for the new floor. On the Annecy market, where every extra square metre is extremely valuable on resale, this investment nonetheless remains very cost-effective compared with buying a larger property in the same area.

When adding a storey goes hand in hand with improving the insulation of the house, some of the work may qualify for energy renovation grants (MaPrimeRénov', CEE, éco-PTZ zero-interest eco-loan): as an RGE-certified company, we tell you which schemes are available and prepare the applications. For an accurate price, nothing beats a site visit: we provide a free, detailed quote after a feasibility analysis in Annecy, with no obligation.