Intermediate

Setbacks, Height & Site Coverage: PLU Rules Explained

08/04/2026 12 min read

Once you have identified your plot’s zone in the Local Urban Plan (PLU), three rules will concretely determine what you can build and where: the setback from roads and boundaries, the maximum height of the building, and the permitted site coverage. These three parameters, set by Articles 6, 7, 9 and 10 of the zone regulations, are the first thing to check before drawing up any plans. Ignoring them means exposing yourself to an outright refusal of planning permission — or even demolition if the house is already out of the ground.

Why these three rules determine your project

Even before thinking about the number of bedrooms or the roof style, these rules define the buildable envelope of your plot: a virtual volume within which your house must fit entirely. This envelope combines:

A maximum ground coverage (the footprint);
Minimum distances to respect on all four sides (the setbacks);
A height ceiling that nothing can exceed.

Stepping outside this envelope — even by just one metre of roof overhang or an uncalculated covered terrace — is enough to get your application rejected. The good news: these three rules are objective and quantified, so they are easy to check from the sketch phase onwards.

Tip — Before drawing a single plan, first sketch your buildable envelope on your site plan: mark the setback limits from each side, calculate the remaining area, then apply the maximum site coverage. You will immediately know what margin you have to work with.

Setback from public roads (Article 6)

Article 6 of the zone regulations sets the minimum distance between the building and the building line (the boundary between your plot and the public highway). This is also known as the facade setback or road frontage setback.

Typical values by zone

PLU Zone	Typical setback from public road
UA (historic centre)	Mandatory alignment (0 m)
UB (inner suburbs)	0 to 3 m, sometimes mandatory alignment
UC (dense residential)	3 to 5 m
UD (low-density residential)	5 to 8 m
AU (development zone)	5 m, often set by the OAP masterplan

What the setback includes

The setback is measured from the face of the finished wall to the building line. Note that roof overhangs of more than 50 cm, balconies, external staircases and canopies are generally included in the calculation. Read the regulations carefully — some councils explicitly exclude them.

Warning — If your plot fronts two roads (a corner plot), the setback applies on each road. This can considerably reduce your buildable area. On some small corner plots, after applying both setbacks, almost nothing usable remains.

Setback from boundary lines (Article 7)

Article 7 governs the distance between your building and the boundary lines (the borders with your neighbours). This is probably the most emblematic rule in the PLU, and the one that generates the most neighbour disputes.

The H/2 rule, minimum 3 m

The classic wording is: “the distance measured horizontally from any point of the building to the nearest point of the boundary line must be at least equal to half the height of the building, and not less than 3 metres”. In short: L ≥ H/2 and L ≥ 3 m.

In practice, for a house 6 m high at the eaves, the minimum setback is 3 m (since H/2 = 3 m). For a house 9 m high, the setback increases to 4.5 m. The taller the house, the further it must be from the neighbour.

Building on the boundary line: yes or no?

Three cases depending on the regulations:

Free positioning: you can choose between setback or boundary (rare in pure residential areas).
Mandatory setback: building right up to the neighbour’s boundary is impossible (UD and UC zones often).
Boundary building permitted under conditions: generally if the length along the boundary does not exceed a certain value (often 8 to 12 m), if the boundary wall does not exceed a fixed height (often 3.50 m at the eaves), and if the wall has no openings.

Best practice — If you are building on the boundary line, get a written agreement signed by your neighbour before submitting the planning application. It is not a legal requirement, but it defuses 90% of third-party appeals lodged within the two months following the display of the planning permission notice.

Question

Site coverage (Article 9)

Site coverage is defined by Article R.420-1 of the Urban Planning Code as the “vertical projection of the volume of the building, including all overhangs and projections”. In other words: the area of ground your building occupies when viewed from above.

What is included in the footprint

External walls (including thickness)
Roof overhangs, canopies, awnings
Balconies, raised terraces on columns
Covered external staircases
Garage, garden shed, carport
Covered swimming pool (an uncovered pool generally does not count)

What is not included

Ground-level uncovered terraces
Open-air swimming pool basins
Driveways and paths
Planting and fencing

How the maximum permitted footprint is calculated

The regulations express the footprint as a percentage of the plot area or sometimes as an absolute area. Examples:

Typical case	Calculation
Plot 800 sqm · CES 30%	Max footprint = 240 sqm
Plot 500 sqm · CES 25%	Max footprint = 125 sqm
Plot 1,200 sqm · CES 20%	Max footprint = 240 sqm

The Site Coverage Ratio (CES) typically ranges from 10 to 15% in low-density residential zones (UD), 25 to 40% in dense residential zones (UC), and can reach 60 to 80% in town centres (UA).

Warning — Do not confuse site coverage and floor area. Site coverage is a vertical projection (view from above, in sqm). Floor area is the sum of enclosed and covered surfaces, floor by floor. A two-storey house with 80 sqm of footprint can total 160 sqm of floor area. The architect requirement thresholds (150 sqm since 2017) apply to floor area, not footprint.

Maximum height (Article 10)

Article 10 sets the maximum height of the building. Three key concepts to master: the reference point, the eaves height and the ridge height.

The reference point: measured from where?

Height is always measured from a low reference point specified by the regulations:

Natural ground level before works (the most common): measured from the existing ground, before any earthworks.
Finished ground level (rare): from the regraded terrain after works.
Public road level at the plot boundary (in dense urban zones).

This nuance is crucial on sloping plots: if the measurement is taken from the natural ground level, the downhill side of the house may appear to exceed the permitted height when it is in fact compliant.

Eaves height vs ridge height

Two different high points are measured:

Eaves height = up to the junction between the roof and the wall (the roof eaves). Broadly determines the number of storeys.
Ridge height = up to the highest point of the roof. Determines the pitch and the height of the roof space.

The regulations generally set both, for example: “6 m at the eaves and 9 m at the ridge”. This typically allows for ground floor + first floor + convertible loft.

House style	Eaves height	Ridge height
Single storey	3 to 4 m	5 to 7 m
2 storeys	5.5 to 6 m	8 to 10 m
2 storeys + loft	6 to 7 m	9 to 11 m
3 storeys	8 to 9 m	11 to 13 m

Special case: flat roofs

If you are planning a flat roof, the regulations define the height to the parapet (the small border wall). Some zones (UA, older UB) outright prohibit flat roofs or restrict them to outbuildings — check Article 11 (external appearance) at the same time.

Tip — If your regulations allow an eaves height of 6 m but you are set on a single-storey house, do not use that headroom to inflate your ceiling height to 3.20 m “because you can”. You will pay more for heating, more for insulation, and you will lose the option of adding a future upper floor. Keep your options open.

Calculating what you can build: a worked example

Let us take a realistic plot to make all of this concrete.

Plot data:

Rectangular plot of 20 m × 40 m = 800 sqm
Zone UD, rules: road setback 5 m, boundary setback H/2 (min 3 m), CES 25%, height 6 m at eaves / 9 m at ridge

Step 1 — Calculate the ground envelope:

Available width: 20 − (3 + 3) = 14 m
Available depth: 40 − (5 + 3) = 32 m
Area within which the building can be positioned: 14 × 32 = 448 sqm

Step 2 — Apply the CES:

Maximum permitted footprint: 800 × 0.25 = 200 sqm

Step 3 — Buildable volume:

200 sqm footprint over 1 or 2 levels depending on the height chosen
With 2 storeys (full upper floor): up to 400 sqm of floor area in theory

Conclusion: on this plot, you could build a two-storey house of 200 sqm footprint and 400 sqm floor area. But the site coverage is likely the limiting factor — the 448 sqm “geometrically possible” is not achievable because of the 25% CES.

Conseil

flowchart TD A{Reading the
zone regulations} --> B[Article 6
Road setback] A --> C[Article 7
Boundary setback] A --> D[Article 9
Footprint CES] A --> E[Article 10
Height] B --> F[Calculate
ground envelope] C --> F F --> G{Geometric area
OK?} D --> H{Area respects
CES?} G -->|No| I[Reduce footprint
or compact plan] G -->|Yes| J[Check height] H -->|No| I H -->|Yes| J E --> J J --> K[Plan compliant
with PLU] style A fill:#0F4C81,stroke:#0F4C81,color:#fff style B fill:#FDFCF9,stroke:#C67A3C,color:#0F4C81 style C fill:#FDFCF9,stroke:#C67A3C,color:#0F4C81 style D fill:#FDFCF9,stroke:#C67A3C,color:#0F4C81 style E fill:#FDFCF9,stroke:#C67A3C,color:#0F4C81 style F fill:#F58220,stroke:#F58220,color:#fff style G fill:#0F4C81,stroke:#0F4C81,color:#fff style H fill:#0F4C81,stroke:#0F4C81,color:#fff style I fill:#CD212A,stroke:#CD212A,color:#fff style J fill:#F58220,stroke:#F58220,color:#fff style K fill:#56C6A9,stroke:#56C6A9,color:#fff

Classic mistakes to avoid

Forgetting overhangs in the footprint calculation

This is the most common error. You size your house at 199 sqm to stay under the 200 sqm CES limit, then add 60 cm of roof overhang all the way around. Result: your actual footprint exceeds 200 sqm and your application is refused.

Measuring the setback from the wrong point

The setback is measured from the official building line, not from the existing fence or the edge of the tarmac. The building line may differ from what you see on the ground. If in doubt, request an alignment order (arrêté d’alignement) from the town hall.

Confusing boundary line and road boundary

A boundary line is a marker between you and a private neighbour. A boundary with a public road falls under Article 6, not Article 7. On plots bordering a private dead end, the status can be ambiguous — a planning certificate clarifies the situation.

Overlooking mutual positioning rules

Article 8 (often forgotten) governs the positioning of buildings relative to one another on the same plot. If you are building a house plus a detached garage, they must respect a distance between them, generally L ≥ H/2 or L ≥ 4 m.

Underestimating the impact of slope

On a sloping plot, height may be measured from several points. A house that appears to comply with the 6 m eaves height on the uphill side may in reality be at 8 m on the downhill side. Always check the exact definition in the regulations and draw a cross-section of the natural ground.

Going further

These rules are inseparable from a full reading of the zone regulations. To build a complete picture of your constraints, also consult:

PLU zoning and sub-zones — to identify which article applies to you
Regulatory dimensions on a plan — to mark these distances on your site plan
Planning permission vs prior declaration — to know which form to submit
Geoportail de l’urbanisme — to download the regulations for your commune