🏗️ Are you planning to extend your house, dig a swimming pool or simply install a garden shed? Before you even get the shovel out the door, there's an essential step to take: choosing the right planning permission. Prior declaration or planning permission? The answer depends on the size, nature and location of your work.
Making the wrong choice is not trivial ⚠️ : it can cost you dearly. Refusal of the application, suspension of work, hefty fines, even the obligation to demolish what you've just built... it's best to avoid it.
In this article, I provide a clear explanation of the difference between these two approaches, the concrete cases where one or the other applies, and the right reflexes to avoid making a mistake.
1. The basics you need to know 📚
a. Preliminary works declaration (DP) ✍️
La prior declarationThis is the 'light' form of authorisation. It is mainly used to notify the town hall of modest works that change the external appearance of a building or add a small surface area.
Its role? To check that your project complies with the PLU (Plan Local d'Urbanisme) and local regulations. You submit a form (Cerfa), attach a few plans and photos, and then the town hall will generally one month to respond. In certain cases (protected areas, ABF sectors), the deadline can be extended to two months.
In short, it's a simplified procedure, but compulsory as soon as your work visually alters the existing building.
b. Planning permission (PC) 🏠
Le planning permissionThis takes longer to process, because the local council checks not only local regulations, but also compliance with building standards, and may consult specialist departments (such as the Architectes des Bâtiments de France).
The deadline varies according to the type of project: two months for a detached house and three months for other buildings. In sensitive areas, plan even more.
As soon as you exceed certain surface area thresholds, planning permission becomes essential.
2. How do you know which one to ask for? 🤔
There are three key criteria: the surface area, nature of the work and location of the plot.
a. Surface thresholds
Two important concepts:
- Floor area enclosed and covered space with a ceiling height of over 1.80 m.
- Floor area The ground projection of the volume of the building (including roof and overhangs).
The main rules :
- Less than 5 m² → in general, nothing to ask.
- From 5 to 20 m² → prior declaration.
- From 20 to 40 m² → DP possible in urban zones with PLU, if the total surface area after works does not exceed 150 m².
- Over 40 m² → planning permission required.
- Over 150 m² (total surface area after works) → planning permission + use of an architect.
b. Type of work
- New construction The minimum requirement is a PD, or even a permit if the thresholds are exceeded.
- House extension same threshold rules. Example: a 30 m² extension in an urban zone → PD possible if the house remains under 150 m².
- Swimming pool :
- from 10 to 100 m² → DP
- over 100 m² → permit
- Garden shed between 5 and 20 m² → DP.
- Fence : sometimes subject to planning permission, depending on the PLU.
- Change of use (garage converted into bedroom) minimum one RFP, permitted if the structure is modified.
- Raising often a building permit.
c. Location
- Protected areas (ABF, historic monuments, listed sites) Stricter rules, stricter authorisation.
- Local PLU The following restrictions may apply: height, setback, external appearance.
- Urban area with PLU vs rural area Different thresholds (40 m² in urban areas, 20 m² elsewhere).
3. Concrete examples 📝
- 15 m² veranda → prior declaration.
- 35 m² extension in urban zone PLU → DP if total surface area < 150 m², otherwise planning permission + architect.
- 20 m² uncovered swimming pool → DP.
- 50 m² garage → compulsory licence.
4. If you're wrong... 😬
The risks are real:
- Refusal of the application → waste of time.
- Unauthorised work → immediate interruption, fines of up to €300,000, or even compulsory demolition.
- Insurance that refuses to pay out in the event of a claim.
- Unsaleable until the situation is regularised.
In short, it is better to take 1 hour to check your file than 6 months to regularise it.
5. The right reflexes to adopt ✅
- Consult the PLU prior to any project (at the town hall or on the commune's website).
- Ask the town planning department for advice It's free and very useful.
- Getting support if necessary: architect, project manager or draughtsman.
- Testing official simulators (Service-Public.fr in particular).
- Anticipating deadlines :
- 1 to 2 months for an RFP
- 2 to 3 months for a licence
- 2 months for third party appeals after posting
The question What is the difference between "prior declaration" and "planning permission"? is not just a formality: it's the key to securing your project.
Remember the essentials:
- DP for small-scale works (up to 20 or 40 m² in urban areas with a PLU).
- Permission is required if the thresholds are exceeded or if the building is of a substantial size.
- Architect required for buildings over 150 m².
And above all, remember that the town hall is your ally. Before taking the plunge, consult the PLU, talk to the town planning department and, if necessary, seek professional help.
By taking the right steps, you can avoid unpleasant surprises and save precious time so that you can enjoy your new veranda, swimming pool or extension with complete peace of mind.
