Every square meter counts in setting the price of a property. But it is not uncommon to have unpleasant surprises and to discover too late that the surface of your accommodation is smaller than you thought. Here are the rules to know to perform a reliable calculation.
To each his own
Above all, you have to know that there are not one but three possible equations depending on the circumstances. The most well-known “Carrez law” measurement is made compulsory for any property located in co-ownership. However, it is not taxed for single-family homes. The latter are rather measured against their living space, at the seller’s choice.
Another scenario: the rental of empty accommodation. In this case, the legislation requires the lessor to mention in the contract this living space resulting from the Boutin law. In addition, real estate experts also refer to the so-called useful surface of a property to determine the rent ceiling to be applied within the framework of a tax exemption regime such as Pinel, or even during the purchase or construction. of a good financed by a social loan. Always state which equation you are referring to, to avoid further litigation.
Some excluded premises
The measurement in Carrez law takes into account all the closed and covered rooms of the house with a ceiling height of at least 1.80 m. To perform the calculation, measure the floor area of the premises by deducting the thickness of the walls, partitions, steps, stairwells, ducts and doorways and windows. An attic and attic, even unfinished, as well as a veranda and a basement can be counted as long as they meet the ceiling height condition. On the other hand, we exclude the independent lots of less than 8 m2 (the studio located at the bottom of the garden will therefore not count), as well as the non-habitable parts such as the garage and the cellar, and uncovered such as a terrace or a balcony. .
The living area only takes into account the fitted out spaces that can be directly occupied. Independent lots of less than 8 m2 are therefore taken into account here, while the veranda and the unfinished attic are excluded.
Finally, the useful surface adds to the Carrez law surface all the annexes external to the accommodation, always subject to a ceiling height of 1.80 m, such as a cellar, a basement, a shed, a workshop. and convertible attic space, as well as a hard or upstairs terrace within the limit of 9 m2.
Alone or with a pro
To put it into practice, you can use an old-fashioned tape measure or opt for a more precise laser rangefinder. Position yourself in each room to take your measurements (which automatically excludes partitions and walls), making sure to position your device above the baseboards. Then multiply the width by the length to get the number of square meters. Then add the area of the pieces to get your final result.
Things get complicated when you have sloping ceilings, fitted wardrobes or rounded walls. However, if you make a measurement error of more than 5%, the buyer or the tenant can claim compensation. Although the law does not require the use of a professional, it is strongly recommended to use a state-approved diagnostician, at a cost of 70 to 200 euros. The list of these professionals is available on the website of the Ministry of Ecology: diagnostiqueurs.din.developpement-durable.gouv.fr