What criteria determine whether a private plot contains protected green spaces, and what obligations arise for its owner? Between the local urban planning document (PLU) of your municipality, recent laws on hedge protection, and the Zero Net Artificialization objective, the constraints overlap. This article compares the main regulatory frameworks and analyzes their concrete effects on private parcels.
Article 13 of the PLU and biotope coefficient: two urban planning tools to distinguish
The rules governing the greening of a private plot do not come from a single text. Two mechanisms coexist in local urban planning documents, and their logics differ.
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| Criterion | Article 13 of the zoning regulation (PLU) | Biotope coefficient by surface area (CBS) |
|---|---|---|
| Legal basis | Urban planning code, zoning regulation of the PLU | PLU or PLUi, often introduced during revisions post-2021 |
| What is measured | Percentage of area in bare soil or green spaces to be maintained on the parcel | Ratio between eco-developable surfaces (bare soil, green roofs, permeable surfaces) and total surface area of the plot |
| Scope | Applies when applying for a building or development permit | Can apply to any modification of land use, including without construction |
| Control | Permit instruction then verification | Permit instruction, even post-control depending on the municipality |
| Post-2021 trend | Raised thresholds in PLUs revised after the Climate and Resilience law | Increasing adoption, particularly in Île-de-France and Auvergne-Rhône-Alpes |
Understanding the regulation of protected green spaces applicable to your plot begins with reading the zoning regulation of your PLU. Article 13 may impose a minimum percentage of vegetated surface area, but the CBS also values technical solutions such as green roofs or permeable coverings.
In practice, a plot subject to the CBS has more levers than a plot governed solely by Article 13. The CBS allows for technical compensations where Article 13 often requires strict bare soil.
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Climate and Resilience Law, ZAN objective: what changes for private parcels
The law of August 22, 2021, known as “Climate and Resilience,” set the objective of Zero Net Artificialization by the deadline established by the legislator. Since then, PLUs adopted or revised have integrated minimum obligations for bare soil or vegetated surfaces on private parcels, including in already urbanized areas.
This mechanism transforms ordinary gardens into de facto protected green spaces. An owner wishing to enlarge their house, add a garage, or impermeabilize a driveway may have their permit denied if the project reduces the vegetated surface below the threshold set by the revised PLU.
Which parcels are most affected?
Dense municipalities, particularly those in Île-de-France, apply the most stringent thresholds. Several regions now condition their energy renovation aid on the preservation or creation of cool islands on private parcels: maintaining high-stem trees, limiting impermeable surfaces, minimum biotope coefficient.
In Auvergne-Rhône-Alpes, similar mechanisms exist within the framework of regional agreements for renaturation. The common point: greening becomes a condition for accessing public funding, not just an urban planning constraint.
Protection of hedges and trees outside forests: the law of April 15, 2024
Law No. 2024-346 of April 15, 2024, created a distinct regime, codified around Articles L.350-3 and following of the Environmental Code. It prohibits the destruction or significant degradation of hedges and trees outside forests without compensation, including on private properties.
- Exceptions are limited: safety of persons, health of plants, public utility easements. A dead or dangerous tree can be felled, but the burden of proof lies with the owner.
- A replanting obligation applies when destruction is authorized. Replanting must compensate for the loss in terms of linear or surface area, according to modalities controlled by state services.
- Hedges classified under the PLU already enjoyed protection. The 2024 law extends this logic to unclassified hedges, as long as they fulfill ecological functions (corridors, erosion control, biodiversity).
This law directly impacts development projects on private land. Before submitting a permit, it is essential to check whether any hedges or isolated trees present on the parcel fall under this protection.
PLU, hedge law, and regional aid: how these mechanisms overlap on the same plot
An owner may find themselves simultaneously subject to three levels of constraints: the zoning regulation of the PLU (Article 13 or CBS), the 2024 hedge protection law, and the conditions for maintaining greening related to regional aid.
The main trap lies in the order of verifications. Consulting the PLU alone is no longer sufficient since 2024. A parcel may comply with the percentage of bare soil imposed by the PLU while violating the prohibition on destroying a hedge protected by the Environmental Code.
- Step 1: read the zoning regulation of the PLU (Article 13 and, if applicable, CBS) to know the greening thresholds.
- Step 2: identify the hedges and trees outside forests on the parcel and check if they fall under Law No. 2024-346.
- Step 3: if public aid is sought (renovation, construction), check the regional conditions for maintaining cool islands or green networks.
In contrast, a plot located in an agricultural or natural zone of the PLU (zones A or N) falls under an even more restrictive regime, where constructibility itself is limited. Greening obligations are rarely added, as artificialization is already heavily regulated there.
The overlap of these mechanisms makes each development project specific to its parcel. Two neighboring plots may be subject to different rules if one contains a protected hedge and the other does not, or if their PLU zones differ. Checking each regulatory layer before submitting a permit remains the only reliable method to avoid a refusal or a formal notice.