The Key to an Accurate Real Estate Valuation
When evaluating a property, one of the most important factors is its surface area, both because square footage is almost always the preferred metric for valuations and because the property’s overall size helps place it within a specific market segment. But here’s the thing: there’s no single way to measure it! Depending on the method used, the square footage can vary significantly.
If we want to compare two properties correctly, we must always use the same type of measurement.
Today, I’ll explain in a simple and practical way the three main types of surface area used in real estate:
- Gross Floor Area (Superficie Catastale)
- Usable Floor Area (Superficie Calpestabile)
- Commercial Floor Area (Superficie Commerciale)
Let’s break them down!
1️⃣ Gross Floor Area (Superficie Catastale): The Official Measurement
The gross floor area is the official figure found in legal documents, such as property deeds or land registry records. It is calculated according to government standards and includes:
✅ The total surface area of the home, including walls
✅ A percentage of balconies, terraces, basements, gardens, and other attached spaces
Why is it important?
Because it’s the most reliable and comparable measurement between properties. When I conduct a property valuation, I use the gross floor area because it’s recorded in official sales documents from previously sold properties, making it an objective and trustworthy reference.
2️⃣ Usable Floor Area (Superficie Calpestabile): The Space You Actually Live In
The usable floor area refers to the actual space you can walk on inside the home.
✅ Measured within the walls, it only includes spaces that are truly livable.
✅ Does NOT include wall thickness, balconies, terraces, or other external spaces.
Why is it important?
Because it gives a clear idea of the actual livable space inside the home. If you’re planning furniture placement or trying to visualize room sizes, this is the measurement to look at!
3️⃣ Commercial Floor Area (Superficie Commerciale): The One That Affects Price
The commercial floor area is the most commonly used measurement for determining a property’s market value.
✅ It includes everything:
- Usable floor area at 100%
- Internal and perimeter walls (up to a certain thickness)
- A percentage of balconies, terraces, gardens, basements, garages, and other additional spaces
Common percentage calculations:
- Balconies & terraces: 25%-35%
- Gardens: 15% (if small), 2% (if very large)
- Basements: 20%-50%
- Garages: 40%-60%
Why is it important?
Because it’s the basis for calculating price per square meter. However, be careful! The commercial floor area can sometimes inflate the perceived value of a property, especially if it includes multiple extra spaces.
Conclusion: Which Measurement Should You Use?
🔹 Looking for an official and standardized measurement? Use gross floor area.
🔹 Want to know how much space you actually have? Check the usable floor area.
🔹 Trying to estimate the market value? Consider the commercial floor area.
Golden rule for comparisons: Always use the same measurement type! If you’re comparing two properties, make sure you’re using the same metric—otherwise, the comparison won’t be accurate.
And now, the next time you see a real estate listing, you’ll know exactly what those numbers mean! 🚀
