The commercial surface area of a property is a measure of the available space of the property. We all know, more or less, the surface area of the house we live in: 80, 100, 200 square meters, etc.

However, this measurement only takes into account the floor area of the property. The commercial surface area is different because it also takes into account spaces that are added to the interior of the house: the perimeter walls, balconies and terraces, gardens and yards.

Let’s see how commercial surface area is determined. The procedure is as follows:

• first, we start with the floor area of the house, expressed in square meters;
• to this we add the area corresponding to the perimeter walls (i.e., those surrounding the house all around) and the interior walls. How do you calculate the surface area on which the walls rest? It obviously can’t be done with a tape measure, so we simply add 5% to the floor area;
• at this point you add the balconies, but only for 30% of their area. If, for example, the balconies measure 20 square meters, 30% of that area, or 6 square meters, will be calculated;
• gardens and terraces are then added, again for a percentage of 30% of their area.

Now we have the commercial surface area of the property.

Next, we will have to multiply it by the price per square meter. Let’s quickly see what this is and how to get it.

The price per square meter is the value attributed to one square meter of a property. It varies from one city to another, and, even within the same city, from one neighborhood to another and from one street to another. Even within the same building, apartments on different floors with different exposures can have a price per square meter that is significantly different.

How do you find the price per square meter of a property? A very useful tool can be the website of the Agenzia delle Entrate, which provides a special database containing data from throughout Italy. All you have to do is enter the city and street where the property is located to find the relevant information.

This is also a very useful tool for those who want to rent a property: using the average price per square meter, it’s possible to calculate the monthly rent.

A coefficient of merit is an amount that gets added to or subtracted from the value of the property. They vary based on several factors, for example age and condition of the property, floor, view, exposure, light, type of heating, and whether the property is leased or not.

So far we have seen how to calculate the value of a residential property. How, on the other hand, should we proceed if we need to value a warehouse or an apartment to be used as an office?

In this case you also start by calculating the commercial surface area, following the criteria set out above. Then, you need to multiply the commercial surface area by the price per square meter, found on the website of the Agenzia delle Entrate.

In this way, you get the base value of the property, which will have to be increased or decreased according to the coefficients of merit, which in the case of commercial properties are: floor; particularly favorable location for commerce; storefronts/shop windows.