Freshen up, add a bedroom, renovate, join or divide, change the use, split off a plot, enlarge. Ranked from the simplest to the heaviest, each with what notarial sales in Montluçon, Vichy and Moulins show, and the national ranking of the towns where it pays most.
The scale combines three criteria: the works, planning permission and the number of professionals involved. The times shown are the legal processing times, excluding works.
| Technique | Permission | Professionals | Administrative time |
|---|---|---|---|
| T1Freshening up and staging Light | None. Prior declaration only if the exterior changes (façade, windows and doors). | Tradespeople (painting, floors), home staging. | No administrative delay. |
| T2Creating a bedroom or a room Light to moderate | None for an internal partition. Co-owners’ approval if a load-bearing wall or a common part is affected. | Plasterer, electrician; structural engineer if a load-bearing wall is involved. | None, except a vote at the co-owners’ meeting. |
| T3Energy renovation: gaining EPC ratings Moderate | Prior declaration if the exterior changes: external insulation, windows, visible heat pump. | Auditor or energy assessor, RGE-certified tradespeople, France Rénov’ adviser. | Grant application filed before the works; prior declaration: 1 months of processing. |
| T4Converting lofts and cellars, joining units Moderate | Prior declaration for 5 to 20 m² of floor area created (up to 40 m² in an urban zone of a PLU), permit above that; roof windows: prior declaration. | Tradespeople; surveyor, notary and co-owners’ meeting when joining units. | 1 months (prior declaration), 2 months (permit for a house). |
| T5Change of use of premises Moderate to major | Prior declaration; building permit if the structure or the façade changes. | Architect depending on the area, tradespeople, Consuel for the electrics. | 1 to 3 months for processing, then 2 months for third-party appeals. |
| T6Splitting off a building plot (BIMBY) Moderate to major | Prior declaration of division; development permit if a road or common areas are created. | Chartered surveyor, notary; network operators if the plot needs utilities. | 1 months (prior declaration) or 3 months (development permit), then 2 months for appeals. |
| T7Dividing into several homes Major | Prior declaration or permit depending on the works; co-owners’ approval. | Surveyor, notary, tradespeople, Enedis for the meters. | Several months: processing, vote at the co-owners’ meeting, connections. |
| T8Enlarging: extension and extra storey Very major | Prior declaration up to 20 m² (40 m² in an urban zone of a PLU), permit above that; architect compulsory above 150 m² in total. | Architect, structural engineering firm, contractors, building-damage insurance. | 2 months of processing for a house, then 2 months for appeals. |
Verdict drawn from each town’s notarial sales. The detailed figures are on each page.
| Technique | Montluçon | Vichy | Moulins |
|---|---|---|---|
| Freshen up | Everywhere, on a small budget | Everywhere, on a small budget | Everywhere, on a small budget |
| Add a bedroom | Pays for flats | No premium measured | No premium measured |
| Energy renovation | Profitable with grants or letting | Pays for itself in flats | Profitable with grants or letting |
| Lofts, joining units | No premium for large homes | Large homes are worth more per m² | No premium for large homes |
| Change of use | Possible, with two exceptions | Supported by the conurbation | Supported by the town |
| Split off a plot | Not very worthwhile | Worthwhile | Worthwhile |
| Divide | Small units are worth more per m² | Yes, except near the parks | Small units are worth more per m² |
| Enlarge | Depends on the quote | Depends on the quote | Depends on the quote |
A micro-area can contradict its town: near the parks and spa of Vichy, dividing a large flat loses value, whereas it pays in the rest of the town. See the area analysis →
The 1,714 towns analysed on the site, ranked on the indicator that decides each technique: price gap by EPC, land prices, prices of small and large units, price per m² and market speed.
Saint-Jean-Cap-Ferrat · Saint-Tropez · Ramatuelle · Neuilly-sur-Seine · Megève · Chamonix-Mont-Blanc
The full ranking →For any property that looks dated, cluttered or poorly presented in photos.
Full page →T2For a large living room, a spacious closed kitchen, a badly placed study. The typical case: a large 2-room home that can become a 3-room home.
Full page →T3For homes rated E, F or G, and for those whose EPC predates 2026.
Full page →T4For a top floor under the roof, a house with an attic, a flat next to another unit or a cellar.
Full page →T5For a garage, a barn, a workshop, offices or an empty ground-floor shop.
Full page →T6For a house with a large garden, especially one that borders a road or lane. Also known as BIMBY (“Build in my backyard”).
Full page →T7For a large house, a large older flat, a small building sold as a whole.
Full page →T8For a house with room on the plot, or a building where the local plan allows extra height.
Full page →Before making an offer, you need to know what the property is worth here: actual recorded sales nearby, the effect of its energy rating (EPC), the cost of works, the planning rules for the plot. I go through this analysis with you, and an adviser from the network can visit it for you.