Before understanding how to calculate the retail space of a store, it’s important to define what retail space actually is. This is often misunderstood, as “commercial” refers to the purpose of the place, i.e., to sales or commerce. This isn’t the case.
At the same time, it’s important to understand that the retail space of a store has the same meaning when referring to any other property, be it a private residence, a condominium, or a business. It’s almost automatic to use a few simple words to define other types of space we might hear about when buying or selling a store, and it’s therefore important to be aware of them.
When approaching the sale or purchase of a property, two key factors for understanding the space and value of the building are its size, measured in square meters, and its price, measured in euros (per square meter).
It’s possible that, looking at the same property, slightly different surface areas may be obtained, depending on the type of measurement used.
Assuming a building measures 100 square meters based on net internal area, you should expect a slightly larger square footage if you calculate it using the gross internal area, and even larger if you calculate it using the gross external area. These small differences, however, can have a significant impact, especially if you’re interested in purchasing a shop, depending on the type of sales the future store will host.
Let’s understand the reason for these possible fluctuations through the definitions:
Net Internal Area refers to the area of a property, determined by the sum of its individual rooms, measured along the perimeter of the walls, for each floor above or below ground. Balconies, terraces, and the like, the thickness of perimeter and interior walls, and the space around pillars and columns are excluded from the calculation.
Gross Internal Area (GIA) refers to the area of a property, measured along the perimeter of the interior walls, for each floor above or below ground. Unlike Net Area (NAA), this also includes the thickness of interior walls, pillars, and columns, and internal circulation spaces, such as stairways or elevator shafts. Balconies, terraces, and similar spaces are excluded.
Gross External Area (GFA) refers to the area of a property, measured along the perimeter of the exterior walls, for each floor above or below ground. This includes all wall thicknesses, pillars, and columns, as well as circulation space, but excludes balconies, terraces, and the like.
But, having made this general introduction, let’s understand what commercial area actually is and how it can be calculated.
The commercial area of a property represents an objective and therefore fundamental market parameter, which is why it is also called the saleable commercial area.
Given that there are reference regulations (see, for example, Presidential Decree 138/98) that must be the primary starting point, commercial area can be defined as the sum of covered areas, open areas, and appurtenances, where:
Covered areas include 100% of the floor space and non-load-bearing internal walls, 50% of the boundary walls with other properties, and do not include rooms with a height of less than 150 cm;
Open areas include terraces, balconies, gardens, patios, and similar areas with varying percentages. Verandas are considered at 60%. Uncovered balconies and terraces are considered 25%, covered 35%, and patios and porches are considered 35%. Apartment gardens are considered 15%, and villa gardens 10%.
Appurtenances, on the other hand, include cellars and parking spaces (covered and uncovered). In this case, the percentages vary more, based on their size, quality, and location. Generally, attics are considered 80%, habitable basements 60%, cellars 25%, garages 40-80%, and uncovered parking spaces 25%.
Therefore, when selling or buying, it is good practice to refer to this parameter, the most objective one. Often, however, people are confused by the concept of floor space, which is certainly useful for getting an idea of the livable and usable area for the store, but it is much less influential in calculating the sale or purchase price of a property, so much so that it is only one of the parameters used to calculate the Retail Area.
Article written by the staff of Inside Project, architects in Verona and throughout Italy.