Cannes UB Zone PLU: Is Your Ground Coverage Ratio Over the Limit?

Ground coverage ratio in the UB zone: what Cannes’ local urban plan (PLU) says

You’re preparing a construction or extension project on a plot located in the UB zone in Cannes. Cannes’ Local Urban Plan (PLU) sets a maximum ground coverage ratio (known in France as the CES — coefficient d’emprise au sol). You run your calculations and the project looks compliant, but the town’s planning department flags an overrun. This situation usually stems from a misunderstanding of what actually counts toward the ground coverage calculation.

Here’s how to correctly calculate the ground coverage ratio in Cannes’ UB zone, which surfaces are taken into account, and what options exist if your project isn’t compliant.

Regulatory definition of ground coverage

Ground coverage is defined in Article R151-1 of the French Planning Code as « the vertical projection of the building’s volume, including all overhangs and projections. » However, this article allows the PLU to refine or adapt this definition.

Cannes’ PLU, in its UB zone regulations, spells out exactly what counts toward the ground coverage calculation:

• The main building (including basements that are not fully below ground)
• Outbuildings (garages, sheds, utility rooms)
• Roof overhangs greater than 0.60 m
• Raised terraces higher than 0.60 m
• Uncovered swimming pools
• Access ramps and raised slabs

The following elements are generally excluded from the calculation:

• Ground-level terraces (flush with the natural terrain)
• Uncovered, wall-free pergolas
• Roof overhangs of less than 0.60 m
• Outdoor steps and stairs of less than 0.60 m in height

These details matter a great deal: a 20 m² raised terrace you forgot to include can be enough to tip your project into non-compliance.

The maximum ground coverage ratio in Cannes’ UB zone

Cannes’ PLU sets a maximum ground coverage ratio for the UB zone that generally falls between 40% and 50%, depending on the sub-zone (UBa, UBb, etc.). This rate also varies according to plot size.

You must check:

• The written regulations for the UB zone (Article 9, covering ground coverage)
• The zoning map, which may identify sub-zones with specific rules
• Any applicable Development and Planning Guidelines (OAP)

These documents are available at Cannes town hall or on the Géoportail de l’urbanisme.

Calculating the ratio in practice: method and common pitfalls

The ground coverage ratio is calculated using the following formula:

Ratio = (Total ground coverage) / Plot surface area × 100

Take the example of a 300 m² plot in the UB zone with a maximum ratio of 40%.

Your project includes:

• House: 110 m² of ground coverage
• 0.80 m roof overhang on three sides: 12 m²
• Raised terrace at 0.70 m: 18 m²
• Swimming pool: 20 m²

Total coverage: 110 + 12 + 18 + 20 = 160 m²

Actual ratio: 160 / 300 × 100 = 53.3%

Maximum allowed: 40%

You’re over by 13.3 points, or 40 m² too much. The building permit will be refused.

The most common mistakes come from overlooking roof overhangs (often an extra 10 to 15 m²), raised terraces, and swimming pools — all of which count toward ground coverage as soon as they meet the PLU’s criteria.

Building permit application: required documents

Article R431-7 of the Planning Code lists the documents required for a building permit application, including:

• The site plan (PCMI2), which shows the plot’s surface area
• Elevation and roof drawings (PCMI5)
• A graphic document showing how the project fits into its surroundings (PCMI6)
• A written description of the site and the project (PCMI4)

On the site plan, you must state the total ground coverage, calculated in accordance with the PLU. The planning department checks this figure. Any error — intentional or not — results in either a refusal or a permit that could later be annulled.

Consequences of a non-compliant ground coverage ratio

Permit refusal

If the ratio exceeds the allowed threshold, Cannes town hall will refuse the building permit. You then have two months to file an administrative appeal, followed by a further two months to bring the case before the Nice Administrative Court if the refusal is upheld.

Building without a permit or exceeding the allowed ratio

If you build without a permit, or beyond the permitted ground coverage, you risk:

• A formal notice to file for regularisation
• A criminal fine (Article L480-4 of the Planning Code) of up to €300 per m² of non-compliant surface area
• An order to bring the property into compliance or to demolish (Article L480-1)
• Difficulties when selling (a price reduction, or the sale being annulled by the buyer under Article 1617 of the Civil Code in cases of hidden defects or non-compliance)

Partial demolition costs range from €150 to €300 per m², depending on the work involved. Demolishing a 20 m² terrace costs between €3,000 and €6,000, not including legal fees and court costs.

Solutions if you exceed the ratio

Adjusting the project

The most direct solution is to reduce ground coverage:

• Remove or reduce roof overhangs
• Lower raised terraces to below 0.60 m in height
• Reduce the size of the pool or the main building
• Replace an outbuilding with an open, uncovered space

Requesting a minor exemption

Some PLUs allow tolerances for limited extensions or particular situations (corner plots, existing building layout). Check whether Cannes’ UB zone regulations include such provisions.

The request is made by registered letter with acknowledgement of receipt, sent to Cannes town hall’s planning department, and must be backed up with technical and graphic evidence.

Appealing a permit refusal

If you believe the planning department made an error interpreting the regulations or calculating ground coverage, you can:

• File an administrative appeal within two months of being notified of the refusal
• Then bring the case before the Nice Administrative Court within two months of the appeal being rejected, or within four months of filing the appeal if there is no response

The appeal must demonstrate that the town hall’s calculation is incorrect, or that a strict application of the PLU breaches a general principle of planning law (for example, a manifest error of assessment).

The role of technical planning expertise

Before filing a building permit application, it can be worth having a professional check your ground coverage calculation. This review covers:

• The precise interpretation of the UB zone regulations that apply to your plot
• Calculating ground coverage while accounting for every regulated surface
• Identifying room for manoeuvre (reduction, adjustment, possible exemption)
• The compliance of the graphic documents in your application

In the event of a dispute, an independent technical expert assessment provides an objective basis for the disagreement and solid grounds for an administrative appeal.

In summary: key points to watch in Cannes’ UB zone

• Check the written and graphic PLU regulations to find the maximum ratio for your plot
• Calculate ground coverage including every element defined by the PLU (overhangs, terraces, pools, etc.)
• Check compliance before filing your building permit application to avoid a refusal
• If non-compliant, adjust the project or explore the possibility of an exemption
• If a refusal seems contestable, act within the appeal deadlines (two months)

Disputes over ground coverage ratios fall under administrative litigation and are heard by the Nice Administrative Court. Any non-compliant construction exposes you to civil, criminal and commercial sanctions.

📅 Mis à jour le 26/09/2026 — Cassini Expertise, expert bâtiment indépendant (06·83·13·40).