Many future buyers find it difficult to establish the difference between net floor area and gross floor area. It is a crucial aspect to take into account when it comes to analysing a property. That’s why in today’s post we’re going to try and set out the main differences.


The importance of differentiating the two concepts

The market value of a property is defined to a large extent by its surface space and measurements. Location, orientation and build quality being equal, the larger the surface area of a dwelling, the more valuable it will be. In the property adverts we see on websites, real estate portals, etc., we often see references to different types of surface area: gross floor area, net floor area, floor area for calculation purposes, among others. This generates confusion among buyers, given that they find themselves with different, exchanged data that is not based on a uniform criterion.


In buildings, the valid concepts are the gross floor area and the net floor area. In the case of the horizontal property regime, the gross floor area of common areas must also be taken into account. In fact, when we refer to the surface area of a property, the terms most frequently used are gross floor area and net floor area. Let’s analyse the difference between the two concepts.


What is the gross floor area?

The gross floor area is the total covered floor space of the dwelling with a ceiling height of over 150 cm. It also includes the walls and interior spaces that are not used. If covered terraces and porches are open at the sides, 50% of this space enters the gross floor area calculation. If they are enclosed at the sides, 100% of the area is included in the gross floor area calculation.


The gross floor area of dwellings in the horizontal property regime may also include the proportional part of common areas (entrance, staircase, landings) in relation to the participation coefficient that the property has within the building as a whole. As such, and in order to avoid confusion, it is always necessary to specify whether we are referring to the gross floor area of the interior of the dwelling, or to the gross floor area of the property with the common areas.


What is the net floor area?

The net floor area is the interior floor space of the dwelling with a ceiling height over 150 cm that can be used when we are living there (not including walls, pillars, conduits, etc.). In this case, terraces and porches do not enter the calculation, regardless of whether they are roofed over or their sides are enclosed. The proper way to proceed is to list the interior net floor area and specify the surface area of terraces or porches. When we talk about the living area, we always mean the net floor area.


Is the difference established in the cadastre?

The surface area listed in the cadastre is the gross floor area, with common elements if applicable, differentiating the concepts. If there is a garage or external storeroom, swimming pool, etc., these surface areas will also be separately recorded.


The Property Register generally lists both the gross floor area and the net floor area. The gross floor area must match that of the cadastre. Even though the cadastre and the register are independent bodies, it is crucial for them to coincide in order to avoid discrepancies in their data. If they do not coincide, it will be necessary to measure the dwelling in order to check where the error is and subsequently correct it, by means of issuing the corresponding area alteration record. The deeds (Property Register) always take precedence over the cadastre records.


Town councils, notaries and administrative bodies will use the gross floor area for their administrative procedures in respect of municipal licences, deeds, etc. The surface area of the cadastre is very important, because this is the figure used by local councils in order to calculate the corresponding Property Tax amount, and it must always be a true figure. In practical terms, when it comes to buying a property, it will be based above all on the net floor area, enabling buyers to know how much available space the dwelling really has, the space in which they will be able to live and where they will be able to carry out their day-to-day activities.


Real estate consultancy services

At Gènion Immobles we hold all the cadastre, property register and other information regarding the surface areas of the properties in our sales portfolio. As such, on our website, on the property portals with which we work and in our advertising in general, we always list the gross floor areas and net floor area separately and clearly, avoiding confusion and providing information in a clear, unequivocal manner.