Gross Building Area

The Gross Building Area (GCA) is more than a simple number; It is an essential metric that affects different aspects of a property. This concept is crucial for a series of processes, from evaluating a property to its sale or rental potential. In this article, we will delve deeper into the concept of Gross Building Area, exploring what it is, how it is calculated and its importance in the real estate sector.

Definition of Gross Building Area

The Gross Building Area (GBA) is the sum (m2) of the gross areas of all floors , of all floors of a property (above and below the threshold level), as long as they comply with the regulatory ceiling height, measured by exterior perimeter and axes of walls or other separating elements of the building or fraction.

When calculating the Gross Building Area:

Included are:

• interior and exterior walls (these, measured by the axes of the walls or other separating elements of the building or fraction);
• private covered balconies (open or closed);
• steps;
• covered terraces and porches;
• elevator shafts;
• rooms (bedrooms and living rooms);
• kitchens and pantries;
• vestibules and interior circulations;
• sanitary facilities;
• private basements and attics (with use identical to that of the building or fraction and to which coefficient 1 applies);
• storage rooms, storage or other compartments with a similar function;
• garages;
• independent attachments;

The following are excluded:

• areasbuilt below the threshold level, if they are intended exclusively for parking;
• areas intended for basement storage, without regulatory ceiling height (below 2.40 m);
• attics without regulatory height (below 2.40 m);
• technical areas above or below ground (PT, thermal power plant, swimming pool technical area, waste collection compartments, etc.);
• uncovered terraces;
• uncovered balconies and porches;
• public outdoor galleries;
• streets;
• spaces free for public use and covered by the building (entrance halls, stairs, landings, etc.);

This value is crucial in determining the market value of a property and is an essential metric for any real estate transaction.

How to calculate the Gross Building Area

Gross Building Area = Gross Private Area + Gross Dependent Area

Example: If an apartment has 100 m² of Gross Private Area and 20 m² of balcony (dependent area), its GBA will be 120 m².

How to measure Gross Building Area

GCA measurement can be done in several ways, and each one has its advantages and disadvantages:

• Traditional Methods : Tape Measure. This is the most basic and accessible method, but it can be time-consuming and less accurate.
• Technological Methods : Laser Equipment. These devices offer more accurate measurement and are ideal for large spaces.
• Official Documentation : Property Plans. Architectural plans are the most accurate and reliable way to determine GBA.

Gross Building Area measurement rules

The gross areas occupied by the fractions must be delimited as follows:

1. by the outer contour of the building's exterior walls, excluding columns, pillars or other elements detached from the face of the wall;
2. by the outer contour of the walls that separate the units from the common spaces;
3. along the axis of the walls that separate differentfractions.

When measuring the gross area it must be:

1. INCLUDED the entire surface occupied by:
   • indoor spaces;
   • balconies and loggias;
   • covered and paved outdoor spaces (e.g., carport, parking area under the building, circulation gallery);
2. INCLUDED half of the surface occupied by:
   • usable outdoor spaces that constitute coverage of other spaces (e.g., visitable terrace, roof garden);
   • covered but unpaved outdoor spaces (e.g., garden under building);
3. EXCLUDED the surface occupied by:
   • spaces that are not accessible or not usable (e.g., non-accessible basement, attic, non-visitable terrace);
   • spaces with ceiling heights of less than 1.80 m (e.g., technical floor);
   • unenclosed spaces with floors laid directly on the ground (e.g., sidewalks, pedestrian paths, access to garages);
   • spaces that are not covered or paved (e.g., backyard, garden);
   • spaces in the public domain (e.g., road traffic under the building).

It is also observed that:

• stairs, ramps, elevator shafts and plumbing ducts must be included in the gross area of each floor;
• stairs, ramps and other inclined spaces are accounted for in their horizontal projection;
• in double-height spaces, the area must only be counted once;
• in adjacent buildings with common walls, the delimitation of buildings must be done along the axis of these walls4 (e.g., buildings resulting from the division of a building into two);
• in adjacent buildings where one of them abuts another without the construction of an enclosing wall, the delimitation of the added building must be done by the exterior face of the wall of the existing building.

The gross area must be expressed in square meters.

The Importance of Gross Building Area

Understanding the Gross Building Area and its implications is essential for real estate professionals, builders, investors, and also for property buyers and sellers.

• Property Value : GBA is one of the factors that most influence the value of a property. Normally, the larger the built area, the higher the value of the property. This is particularly relevant for clients in the upper-middle and luxury segment, who value properties with larger built areas.
• Urban Planning and Licensing: GBA is a crucial factor in urban planning and the construction licensing process. Determines the maximum size that a building can have on a given lot, influencing the urban design and population density of an area.
• Design and Architecture: GBA influences the architectural design of a building. Architects must consider GBA when designing a building to ensure space is optimized and complies with local codes. On the other hand, the built area is a distinguishing factor in the luxury market, which favors social spaces and large suites.
• Energy Efficiency and Sustainability: GBA can also have an impact on the energy efficiency of a building. Larger buildings may require more energy for heating, cooling and maintenance, affecting thermal comfort planning, as well as the sustainability and operational costs of the property.
• Tax Implications: The built area of a property affects its tax assessment. Properties with higher GBA may have higher taxes, such as the Municipal Property Tax (IMI) in Portugal.
• Legislation and Regulations: Being aware of the GBA of your property can help you avoid legal problems in the future. This is not the first time that I have failed to close a deal due to non-conformities between real areas and areas registered in official documents. Especially in the case of foreign buyers, who are normally well advised from a legal point of view.

Common Mistakes and How to Avoid Them

Measuring GBA can be a complicated process and it is easy to make mistakes.

• Confusion between Gross Area and Useful Area :
  • Error: GBA is often confused with the usable area, which is the truly habitable space. While GBA includes the entire built space, including walls, balconies, etc., useful area refers only to the internal habitable space.
  • How to avoid: Always clarify the difference between these two measurements in your descriptions and in communication with customers. The lack of transparency does not help in the marketing of a property.
• Lack of Verification :
  
  • Error: Sometimes there are inconsistencies in the areas registered in the various official documents related to the property (Land Booklet, Permanent Land Registry Certificate, etc.).
  • How to avoid it: If you are considering selling your home, check all the necessary documents first. If you identify significant differences, you should contact the relevant public services, such as the City Council, the Tax Authority and the Land Registry Office, to align and update this information. Do not leave surprises of this type until the final moment of the transaction, as trust is an essential factor in the process of selling a property.
• Inattention to Changes and Expansions:
  • Error: Not registering with the various official bodies changes or extensions to a property that affect its GBA. I have already lost millions of deals because of this error.
  • How to avoid: It is not enough for the renovations planned by the architect / builder to be registered with the respective City Council.All documents associated with the property will have to be updated with the respective official bodies.
• Errors in marketing and promoting the property:
  • Error: Not using GBA when promoting the sale of a property, using only the useful area.
  • How to avoid: Highlight GBA in your marketing strategies, showing how it adds value to the property. The property is valued as a whole, the living area but also the area of the walls, as they represent a cost and contribute to the real and taxable value of the property.

Frequently Asked Questions about Gross Building Area

These are some of the most frequently asked questions about the Gross Building Area of a property: