Reading French Housing Figures: A Home Fire Watch Guide

French housing figures are not hard to read once you know what each source measures. A DVF transaction file records actual sale prices and dates from notarial deeds, while a notaries index tracks the same sales as a repeat-sales price index. A median price per square metre is only comparable when the territory, the period and the property type are held constant. A DPE or a Georisques report describes a building or a plot at a point in time, not a market trend.

What does a DVF transaction file actually measure?

DVF stands for Demandes de valeurs foncières. The file is published by the French tax authority, the Direction générale des finances publiques, and it lists real estate sales that were registered with a notary. Each row is one transaction: the date, the commune, the address, the type of property (house or flat), the number of rooms, the built surface in square metres, and the total price in euros. The file does not include every sale. It excludes transactions that are not yet finalised, sales under a specific legal regime, and some rural or agricultural properties. It also does not include the notary fees, agency commissions or renovation costs that a buyer actually pays. So a DVF price is a recorded sale price, not a full cost of acquisition.

A common mistake is to treat a DVF file as a live market feed. It is a historical record. The most recent year is often incomplete because notarial deeds take time to be registered. For a current view, readers should check the publication date and the coverage rate noted by the source. For a structured explanation of how these files are built and how to compare them, reading French housing data is a useful reference.

What does a notaries index measure, and how is it different?

A notaries index, often called an indice Notaires-Insee, is a repeat-sales index. It follows the same property over time, or a matched sample of properties, and calculates how prices change between two sales. This method removes the effect of a changing mix of properties. If more large flats sell in one quarter, a simple average price would rise even if no individual flat became more expensive. The notaries index corrects for that. It is published quarterly for existing homes and for new homes, and it is broken down by region and by department. The index is expressed as a number, not as a price per square metre. To get a price level, you need to combine the index with a median price from a transaction file or from a local observatory.

The two sources answer different questions. A DVF file tells you what sold and for how much. A notaries index tells you how the price of a typical property changed. Neither one tells you what a specific flat is worth today. For that, you need a local valuation, a surveyor or a comparison with recent sales of similar properties in the same street or building.

How is a median price per square metre compared like with like?

A median price per square metre is the middle value of all prices per square metre in a given set. Half the sales are above, half are below. It is less sensitive to extreme values than an average. But it is only meaningful if the set is defined consistently. The main traps are territory, period, property type and surface. A median for a whole department mixes urban and rural communes, large and small flats, old and new buildings. A median for a single commune is tighter but can still mix a studio and a four-bedroom flat. A median for a specific type, such as two-room flats of 40 to 60 square metres, is the most comparable.

The period matters too. A median for a full year hides seasonal patterns and price movements within the year. A quarterly median is more reactive but noisier. The source should state the period and the number of sales. A median based on ten sales is fragile. A median based on several hundred sales is more stable. When comparing two territories, check that both medians use the same definition of surface, the same inclusion rules for garages and cellars, and the same treatment of new versus old properties. If one median includes parking and the other does not, the comparison is not like for like.

What does a DPE say, and what does it not say?

A DPE, or diagnostic de performance énergétique, is an energy performance certificate. It gives two labels: one for energy consumption and one for greenhouse gas emissions. It also gives an estimated annual energy cost for a standard use of the dwelling. The DPE is based on a survey of the building, the heating system, the insulation and the ventilation. It is valid for ten years, although some older certificates are being replaced. It does not tell you the actual energy bill of the current occupants. It does not tell you the condition of the roof, the wiring or the plumbing. It does not guarantee that the estimated cost will match your usage. A DPE is a standardised estimate, not a meter reading.

A DPE can also be used for rental rules. In France, a very low energy label can restrict the rent of a dwelling or even ban it from being rented. Those rules change over time and depend on the date of the lease. A DPE is therefore a legal document as well as an informational one. It should be read alongside the other diagnostics, such as asbestos, lead, termites and electricity, which cover different risks.

What does a Georisques report cover?

Georisques is a public platform that maps natural and technological risks by address. It draws on data from several administrations, including the geological survey BRGM and the ministry in charge of ecology. A Georisques report can show flood zones, clay shrinkage and swelling, seismic zones, radon potential, industrial sites and polluted soil. It is a screening tool. It tells you whether a plot is in a risk area according to the available maps. It does not tell you whether a specific house will be flooded next year. It does not replace a geological survey, a flood risk assessment or an insurance contract. It also depends on the accuracy of the address and the date of the map. Some maps are updated frequently, others less so.

When you read a Georisques report, look for the risk categories that are relevant to the property. A flood zone matters more for a ground-floor house than for a fourth-floor flat. Clay shrinkage matters for houses on shallow foundations. Radon matters for basements and ground floors. The report is a starting point for questions, not a final answer.

How should a reader use these sources together?

Start with the question you want to answer. If you want to know what a typical property sold for in a commune last year, use a DVF file and filter by property type and surface. If you want to know whether prices are rising or falling, use a notaries index for the same territory. If you want to compare two communes, use medians with the same definition and check the number of sales. If you want to know the energy performance of a specific dwelling, read its DPE. If you want to know the environmental risks of a plot, read its Georisques report.

Never rely on a single figure. A median without a source and a period is not a fact. A DPE without a date is not a current label. A Georisques report without an address is not a risk assessment. The French public data system is rich but it requires patience. Check the definitions, the millésimes and the limits before you interpret a number. That habit is what separates a useful reading from a misleading one.