House extension
in Savoie.

The Savoie property market has a strong particularity: the price of building land is high (often €200 to €500/m² in urban zones, up to €1,000/m² in the most sought-after municipalities such as Annecy, Aix-les-Bains or around Lac du Bourget). Buying a new plot and building therefore costs far more than extending an existing property, for the same living area.

An extension also lets you keep your surroundings: the children's school, neighbours, nearby shops and transport. In Savoie, PLUs generally allow extensions in U (urban) and AU (future urban) zones, subject to rules on footprint, height and setback. Most detached houses have untapped extension potential: a back garden, unused loft space, the possibility of adding a storey.

Finally, a well-designed extension adds significant value on resale. In the high-demand municipalities of Savoie and Haute-Savoie, each additional square metre is worth €3,000 to €6,000 depending on location. An investment of €60,000 to €80,000 in an extension can therefore add €90,000 to €150,000 in value — a return on investment rarely achieved by other works.

The type of planning authorisation depends on the area created and the zone in which your property is located. In an urban zone covered by a PLU (the case for the vast majority of municipalities in Savoie), the thresholds are as follows:

Prior declaration (déclaration préalable) (DP): for extensions creating between 5 and 40 m² of floor area or footprint, provided the total area after works does not exceed 150 m². Review period: 1 month (2 months in an ABF zone). This is the most common procedure for modest extensions (conservatory, loft conversion, small addition).

Building permit (PC): compulsory above 40 m² of area created (or 20 m² outside a PLU zone), and in all cases if the total area after works exceeds 150 m² (which also makes an architect compulsory). Review period: 2 months (3 months in an ABF zone or listed site). In Savoie, often allow an extra month in tourist municipalities during the summer.

In both cases, we support you from A to Z: survey of the existing building, project plans, complete application (drawings PCMI1 to PCMI8 or DP1 to DP8), submission to the town hall and follow-up of the review. Our applications have an approval rate above 95% thanks to a detailed knowledge of what local planning officers expect. Contact us for a free feasibility study.

A house extension is one of the most profitable property investments in Savoie. The purchase price per m² in sought-after municipalities (Aix-les-Bains, Annecy, Chambéry, lakeside) ranges from €3,500 to €6,500/m² for a detached house. Yet the cost of creating one m² through an extension is €1,500 to €3,500/m² — a difference of €2,000 to €3,000 per m² in your favour.

In practical terms, a 30 m² extension at €2,200/m² (works budget: €66,000) in a municipality where property sells for €4,500 per m² adds a theoretical €135,000 in value — a multiplier of 2. Even allowing for a discount linked to age and architectural integration, the return on investment remains excellent (a ratio of 1.5 to 2.5 depending on the project).

The extensions that add most value in Savoie are: creating a master suite (bedroom + en-suite bathroom), enlarging the living room with a panoramic glazed opening onto the mountains or the lake, and adding a full storey with open views. Conversely, extensions that add little value are garages (low value per m²) and uninsulated conservatories (not counted as living area).

At Atelier NovAlp, we always build added value into our recommendations: orientation, views, durable materials, architectural continuity with the existing building. A project that is well thought out from the design stage sells better and faster.