My Building Footprint is Maxed Out — Can I Still Build in France?
- DN Architectes
- Jan 7
- 3 min read
At DN Architectes, we regularly meet clients convinced that their project is impossible simply because the building footprint on their site is already maxed out. Fortunately, in many cases, options do exist!
What is a Building Footprint in France?
According to the French Urban Planning Code, the building footprint in France refers to the vertical projection of a building’s volume onto the ground, including all overhangs and cantilevers. Importantly, decorative elements like moldings and canopies, or unsupported roof overhangs, are excluded.
However, it’s crucial to note: the definition of a building footprint may vary across municipalities.
For instance:
Nice and Pau: Definitions closely match the national Urban Planning Code.
Bordeaux: Excludes several elements from the footprint calculation, such as:
Sun-shading structures
Energy performance improvement systems (e.g., external wall insulation)
Accessibility devices (e.g., ramps, lifts)
Standalone bike storage
... and other specified structures
Additionally, the height threshold for what counts toward the footprint changes:
In Bordeaux and Pau, structures under 60 cm above natural ground aren’t counted.
In Nice, the threshold is 100 cm, but only for swimming pools.
In Bordeaux, moldings and canopies are excluded from building footprint calculations only if they are less than 1.5 m wide, although the French Urban Planning Code does not define any such threshold.
Key Tip from DN Architectes: Always consult your municipality’s specific urban planning regulations before making decisions about your building footprint.
Where to Find Your Maximum Building Footprint
Your site’s maximum allowable building footprint will be defined in the PLU (Plan Local d’Urbanisme)—your local planning regulation.(We’ve covered this in detail here: How Can I Find Out Which Planning Regulations Apply to My Land in France?)
Typically, the maximum building footprint is expressed as a percentage of your land’s surface area within the same zoning category.If you purchase a property with an existing building, it’s possible that the building footprint capacity has already been fully used.
What About Floor Area or COS?
Previously, urban planning rules included restrictions on floor area known as COS (coefficient d’occupation des sols). This is now obsolete and no longer used in France, as it was seen to encourage urban sprawl and reduce sustainable development.
If someone mentions COS—it no longer applies!
Maximising Extension and New Construction: Other Parameters Matter
Don’t lose hope if your building footprint is maxed out! Other urban planning parameters may still allow you to increase your built area, such as:
1. Building Height
Municipalities regulate how high you can build—this limit might reference the eaves, ridge, parapet, or roof waterproofing layer. Consult your local rules for specifics.
2. Building Massing (Gabarit)
This defines the 3D volume (height, envelope, slopes) within which construction is allowed.
Example : If you have a single-story building and regulations permit, say, 6 m to the eaves, adding another level could increase your living space significantly—even without changing your footprint.
Don’t Forget Green Space Requirements
Municipal rules often require you to maintain a certain portion of vegetated, non-impervious land (green space) on your property.The definition and percentage required can vary, but failing to meet this minimum can block an extension or new construction—even if your footprint isn’t maxed out!
Next Steps: Unlock Your Property’s Full Potential
Urban planning and building regulations can be complex, but there are often creative ways to achieve your vision—even on challenging sites.
Contact DN Architectes today for expert advice on extending your home or developing your site. We can help you navigate every step, from local regulation checks to full project delivery.
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