How do you calculate the square meters of a property?

There are various unsolved mysteries in the world:

- The Bermuda Triangle

- Who killed JFK

- Was the chicken or the egg born first?

for each of these mysteries various theories and possible answers circulate, but no one to date has put down on paper the answer to the greatest mystery of all:

How do you calculate the square meters of a house?

Throughout my years of work, I have had many opportunities to confront sellers and buyers about the consistencies of the properties they were giving me to sell or trying to buy.

Since most people reason with €/sqm values, it is logical that the value of a property is greatly influenced by the area that is taken into consideration.

Today I will try to bring a can of clarity to this obscure world that affects every housing-related area of our lives:

1. How much tax we have to pay
2. How much condominium expenses and thousandths we are entitled to
3. How much are our homes worth

We start as always with the normative basics:

the reference that most technicians take as a basis for calculating the surfaces of houses, is Presidential Decree 138/98, or the Regulations for the revision of census zones and rates of valuation in execution of Law 662/96 surpassed by subsequent UNI standards (EN 15733:2011). It should be emphasized that these are normative sources to be taken as standards to be used by all real estate operators, but they do not represent a constraint in terms of operation.

What are the parameters for calculating real estate surfaces?

We find inAnnex C of Presidential Decree/98 the

TECHNICAL STANDARDS FOR DETERMINING THE CADASTRAL AREA OF THE UNITS
REAL ESTATE FOR ORDINARY USE (GROUPS R, P, T)

General criteria

1. In determining the cadastral area of housing units for ordinary use, interior and exterior perimeter walls are counted in full up to a maximum thickness of 50 cm, and shared walls to the extent of 50 percent up to a maximum thickness of 25 cm.
2. The area of main rooms and accessories, or portions thereof, having a useful height of less than 1.50 m does not enter into the calculation of cadastral area.
3. The area of vertical connecting elements, such as stairs, ramps, elevators and the like, inside building units are computed to the extent of their horizontal projection, regardless of the number of connected floors.

For housing units belonging to the categories of groups R and P, the cadastral area is given by the sum:

(a) 100% of the floor area of the main rooms and accessory rooms directly serving the main rooms such as bathrooms, storage rooms, entrances, hallways and the like;

(b) Of the area of accessory rooms indirectly serving the main rooms, such as attics, cellars and the like, computed to the extent:
- of 50 percent, if communicating with the rooms referred to in (a) above;
- of 25 percent if not communicating.

(c) Of the area of balconies, terraces and the like, which are exclusive appurtenances in the individual housing unit, computed as follows:
- of 30 % up to 25 square meters and 10 % for the excess share, if said appurtenances are communicating with the rooms referred to in (a) above;
- of 15 % up to 25 square meters , and 5 % for the excess share if they are not communicating.

For building units belonging to group P categories, the area of these appurtenances is counted at the rate of 10%;

(d) of the area of theuncovered area or its equivalent, which constitutes exclusive appurtenance of the individual housing unit, computed to the extent of 10%, up to the area defined in subparagraph (a), and 2% for areas exceeding said limit. For parks, gardens, courtyards and the like, which constitute appurtenances of real estate units of category R/2 (villa and cottage), the relevant
surface area is to be computed, using the above criterion, only for the portion exceeding five times the cadastral surface area defined in subparagraph (a).

These are the values that are normally used to calculate the so-called"commercial" area, or SCV Conventional Saleable Area.

I made you a little table so you can understand better:

Table for calculating the commercial floor area of a property:

The correction factors for calculating the square footage of a house:

Having posed these rules of the game, one then begins to have to do some fine work when it comes to assigning corrective percentages to the surfaces of appurtenances that may, depending on their characteristics, have a higher or lower value.

by way of example:

a 5 sq. m. balcony overlooking the ring road cannot have the same coefficient as a habitable terrace overlooking the Arena in Verona or the Grand Canal in Venice. A damp, mold-ridden basement must be worth less than a beautiful basement with vaulted ceilings with above-ground windows... right?

To get around this, correction coefficients have been established that the engineer may or may not apply. These are percentage increases ( +10% -20% etc ) to increase or decrease the real estate values of the consistencies based on objective parameters (e.g. view, valuable historical context, location etc )

That's where you start to get into aspects that go beyond simplistic €/sqm reasoning and correction coefficients. Experience, knowledge of the area and area buying and selling are the only way to attribute a correct value of a property, and these gifts, let me tell you, are proper and exclusive to those who work in the field and have mastered buying and selling!

Do you need a valuation of your property with a consistency calculation for commercial purposes?

Contact me for more information!