There is no such thing as a Hoguet floor area. Carrez or Boutin?

The Hoguet Act contains no floor area: what it actually governs

Act no. 70-9 of 2 January 1970 regulates the conditions under which certain activities relating to buildings and business goodwill may be carried on. Its article 1 lists those activities under nine headings: buying, selling, searching, exchanging, letting or subletting, seasonal or otherwise, unfurnished or furnished, of built or unbuilt property; transactions on business goodwill; subscription for and transfer of shares in property companies; property management; the sale of lists or files; timeshare occupancy; and acting as managing agent of a co-ownership. Its article 3 makes carrying on those activities conditional on holding a professional licence issued by the president of the territorial chamber of commerce and industry, on a financial guarantee where the professional handles client money, and on professional indemnity insurance. Its article 6 requires agreements with such professionals to be in writing. Nowhere does that Act say how to measure a home.

So where does the confusion come from? From the order of 10 January 2017 on consumer information by professionals involved in a property transaction. That order is made under articles L. 111-1 and L. 112-1 of the Consumer Code and article 6-1 of the Hoguet Act: it does belong to the Hoguet ecosystem. It does require a floor area, but in one case only. Its article 4 covers any advertising by a professional listed in article 1 relating to the non-seasonal letting or subletting of a specified property; its paragraph II requires the advertisement to state the municipality and, where applicable, the arrondissement, together with the floor area of the let property expressed in square metres of habitable area. Its article 3, which deals with sale advertisements, requires the sale price, a statement of which party bears the fees, and the amount of the buyer's fees including VAT expressed as a percentage. No floor area.

Do not over-read this: the order does not contain every obligation attaching to a sale advertisement. Article L. 721-1 of the Construction and Housing Code requires, for a co-ownership lot, a statement that the property is in co-ownership, the number of lots and the average annual share of the provisional budget; and article L. 126-33 of the same code requires the energy performance certificate particulars. But none of those provisions requires a floor area in a sale advertisement.

Put plainly: an order made under the Hoguet regime requires a floor area in non-seasonal letting advertisements published by a professional, and many people compress that into the phrase Hoguet floor area. The shorthand is wrong, and it is expensive, because it sends people looking for the wrong rule in the wrong place.

Briveo is the trading name of Liberty House Real Estate SAS, which holds the professional licence for transactions in property and business goodwill issued by the Paris Ile-de-France chamber of commerce and industry. We are therefore directly subject to the Hoguet Act and to the order of 10 January 2017.

Carrez or habitable area: the table that answers in ten seconds

The two areas are not calculated in the same way, do not appear in the same documents, and are not sanctioned in the same way. They can differ by several square metres for the same home without either of them being wrong.

Room by room: what counts and what does not

This is where the two areas genuinely diverge, and it is what most pages leave out. The same home can show 74 sq m Carrez and 68 sq m habitable without any measurement error at all.

The reading rule is simple. Article 4-1 of the decree of 17 March 1967 lays down only three conditions: the room must belong to the private part of the lot, it must be enclosed and covered, and its ceiling height must reach 1.80 m. The provision never asks whether the room is habitable. Article R. 156-1 of the Construction and Housing Code, by contrast, excludes a named list of spaces, whether enclosed and covered or not.

One point is worth knowing: the Court of Cassation holds that measurement relates to the actual state of the premises and not merely to the description in the co-ownership rules. A cellar lawfully converted into a room, distinct from the cellar and more than 1.80 m high, was accordingly counted within the private floor area (Cass. 3rd civ., 5 December 2007, no. 06-19.550).

What you risk if the area is wrong

On the sale of a co-ownership lot, article 46 of the Act of 10 July 1965 sets up two distinct sanctions.

The first is the complete absence of any statement. If no area appears in the promise or in the contract, the deed may be challenged as void on that ground. Proceedings must be brought no later than one month after the notarial deed recording completion of the sale. And signing that notarial deed, if it states the area, forfeits the right to seek annulment of the promise or contract that preceded it.

The second is a shortfall in the measurement. If the actual area is more than one twentieth below the area stated in the deed, the seller bears, at the buyer's request, a reduction in price proportionate to the shortfall. Proceedings must be brought within one year of the notarial deed, on pain of forfeiture. In the other direction, if the actual area is larger, the excess gives rise to no additional payment: the provision is asymmetric, deliberately so.

A worked example. A flat is sold for 300,000 € on a stated area of 62 sq m. Remeasurement establishes 58 sq m. The shortfall is 4 sq m, or 6.45% of the stated area: the one-twentieth threshold is crossed. The reduction in price is proportionate to the shortfall, that is 300,000 x 4 / 62 = 19,354.84 €. With 60 sq m stated and 58 sq m actual, the shortfall falls to 3.33% and no reduction is due under article 46.

On a letting, the mechanism is different. If the habitable area does not appear in the tenancy agreement, article 3 of the Act of 6 July 1989 allows the tenant, within one month of the agreement taking effect, to serve formal notice on the landlord to add that information; failing a reply within one month, or on refusal, the tenant may apply to the court for a reduction in rent within three months of that notice. If the area does appear but is more than one twentieth below the reality, article 3-1 of the same Act gives a right to a reduction in rent proportionate to the shortfall: the landlord has two months to reply to the request, the court may be seised within four months of that same request, and the reduction takes effect from the date the agreement was signed, unless the request is made more than six months after the agreement took effect, in which case it runs only from the request.

Finally, the advertisement itself is sanctioned when it comes from a professional. Any breach of article L. 112-1 of the Consumer Code and of the provisions made under it, including the order of 10 January 2017, carries an administrative fine of up to 3,000 € for an individual and 15,000 € for a legal person (article L. 131-5 of the Consumer Code). The absence of the energy performance certificate particulars from a sale or letting advertisement falls instead under article L. 126-33 of the Construction and Housing Code, which provides its own administrative fine, capped at 3,000 € for an individual and 15,000 € for a legal person.

What people wrongly believe

The Hoguet Act requires a floor area in the advertisement. No. Act no. 70-9 of 2 January 1970 contains no measurement rule. It is article 4 of the order of 10 January 2017 that requires a floor area, only in non-seasonal letting or subletting advertisements published by a professional, and only as habitable area. A sale advertisement is under no legal duty to state any area, even though other particulars are compulsory in one (co-ownership, energy performance certificate, price and fees).

Carrez and habitable area are the same thing. No, and the gap is structural. Unconverted lofts and conservatories are excluded from habitable area by article R. 156-1 of the Construction and Housing Code, whereas they can fall within the Carrez area once they are enclosed, covered, at least 1.80 m high and attached to the private part.

The 5% is an excess: I only compensate what goes beyond it. Wrong, and this is the most expensive mistake. The one twentieth is a trigger threshold, not an excess. Once it is crossed, the reduction is proportionate to the whole of the shortfall. In the example above, the seller repays the 4 missing square metres, not the 0.9 sq m that exceed 5%.

The buyer must prove a loss. No. The Court of Cassation holds that a buyer's knowledge, before the sale, of the property's actual area does not deprive them of the right to a reduction in price, which is not conditional on proof of loss (Cass. 3rd civ., 5 December 2007, no. 06-19.676, reported).

I had it measured by a professional, so I am covered. Not as against the buyer. Article 46 names the seller as the party who owes the reduction in price. The seller's claim against the surveyor is a separate action, which requires proof of fault and causation, and which does not stop the seller paying first.

My house has a Carrez area. Only if it constitutes a lot or part of a lot in a co-ownership, which happens in horizontal co-ownerships. A house sold in full ownership on its own plot falls outside article 46: the stated area is then a contractual and commercial figure, and any inaccuracy falls under the general law (mistake, fraudulent misrepresentation, or the misleading commercial practice of article L. 121-2 of the Consumer Code) rather than the automatic mechanism of article 46.

The energy certificate uses the Carrez area. No. Since the order of 25 March 2024, which amended the order of 31 March 2021 and came into force on 1 July 2024, the energy performance certificate for dwellings works from a reference area: the habitable area within the meaning of article R. 156-1 of the Construction and Housing Code, increased by the area of heated conservatories and of heated spaces principally used for human occupation with a ceiling height of at least 1.80 m. Three different areas can therefore coexist in a single sale file.

My furnished tenancy exposes me to the rent reduction under article 3-1. No, and hardly anyone says so. Article 25-3 of the Act of 6 July 1989 lists exhaustively the articles of Title I that apply to furnished main residences: it names article 3, but not article 3-1. Stating the habitable area therefore remains compulsory in a furnished tenancy, without the rent-reduction mechanism for a shortfall beyond one twentieth being carried across to it.

The special cases that change the answer

Off-plan purchase. The Court of Cassation has held that, in a sale of a building to be constructed governed by article L. 261-10 of the Construction and Housing Code, the area stipulated in the contract means the habitable area within the meaning of article R. 111-2, now R. 156-1, without the parties having had to refer to it expressly, which excludes parts of rooms less than 1.80 m high (Cass. 3rd civ., 18 March 2021, no. 19-24.994, reported).

Building land. No Carrez area: there is no floor of an enclosed and covered room to measure. The cadastral area and the boundary survey take over.

Commercial or professional premises in a co-ownership. Article 46 covers the co-ownership lot without distinguishing by use: commercial premises that constitute a lot are subject to the duty to state the area, subject to the exclusions in the third paragraph (cellar, garage, parking space) and to the 8 sq m threshold.

Seasonal lettings and tourist accommodation. Title I of the Act of 6 July 1989 applies to lettings used as a main residence: the duty to state the habitable area in the contract does not apply to a seasonal letting. And, contrary to a widespread belief, article 4 of the order of 10 January 2017 does not apply either: it covers only non-seasonal letting and subletting. What remains is the display of the professional's fees required by article 2 of the same order, and the general law on consumer information.

Social housing and tax schemes. A fourth concept appears, the useful area, equal to the habitable area of the dwelling increased by half the area of its ancillary spaces on the conditions set by order, under article D. 331-10 of the Construction and Housing Code and the order of 9 May 1995. It serves to calculate benefits and ceilings, not private sales.

Planning. The floor area of article R. 111-22 of the Planning Code, being the sum of the floor areas of each enclosed and covered level measured from the inner face of the facades, determines whether your works require a prior declaration or planning permission. It is not meant to appear in an advertisement or in a deed of sale.

Checking your floor area before you put the property on the market

Three checks are enough to remove most of the risk.

One: identify which regime you are in. Take out your title deed. If it describes a numbered lot with a share of the common parts, you are selling a co-ownership lot and the private floor area is compulsory in the promise as in the deed. If not, it is not.

Two: go back to the co-ownership rules before you measure. They say what belongs to your private part, and therefore what falls within the calculation, bearing in mind that the courts then look to the actual state of the premises. An attic or a basement attached to the lot changes the result by several square metres. Those documents must in any event be given to the buyer under article L. 721-2 of the Construction and Housing Code.

Three: do not reuse an old certificate without testing it against reality. No provision gives the measurement of a private floor area a period of validity, but any change to the lot since it was measured (a partition taken down, a conservatory enclosed, a loft opened up) makes the figure doubtful, and it is the seller who remains liable for the reduction in price.

A correct floor area is only half the work: the asking price still has to match the real market on your street. The Briveo valuation is built on the actual transfers registered by the tax authorities, not on neighbourhood averages. Value your property in 2 minutes, then check what you will be left with using the net proceeds calculator. On fees, Briveo charges 2% including VAT when the sale is concluded online with LAIA, and 5% including VAT when an agent runs the viewings and their buyer signs.