Do your works need a building permit in Luxembourg in 2026?
By Yacine Sahnoune, founder of renov.lu
In Luxembourg, the mayor (bourgmestre) of your municipality issues the building permit (autorisation de bâtir), and the municipal building regulations decide which works are exempt, need a declaration or a permit. New builds, extensions, demolition and change of use require a permit. With no reply after 3 months, the application may be considered refused; a permit is valid for 2 years, extendable once by one year.
- Who decides: the mayor, based on the municipality’s PAG, PAP and building regulations
- Always subject to a permit: construction, conversion, change of use, demolition, backfilling and excavation, except minor works exempted by the municipality
- Often exempt (2023 model regulation): sheds under 12 m², interior works under 20 m² not touching the structure, solar panels on non-protected buildings
- Processing time: no statutory deadline; with no decision after 3 months, an implicit refusal that can be challenged
- Validity: 2 years, plus a single one-year extension (since 11 November 2024)
- Neighbours’ appeal: 3 months from the permit being posted
A project that needs a permit?
Plans, file, follow-up with the municipality: describe your project to receive quotes from architects or businesses established in Luxembourg.
Exempt, declaration or building permit: the three regimes
All works fall under one of three regimes, and your municipality decides which. The amended law of 19 July 2004 on municipal planning makes construction, conversion, change of use, demolition, backfilling and excavation subject to a permit from the mayor; it lets each municipality exempt minor works or subject them to a simple declaration.
| Regime | For which works | Procedure | Before starting |
|---|---|---|---|
| Exempt | Minor works listed in the municipal regulations | None, unless the PAG, the PAP or a protected area says otherwise | Straight away |
| Works declaration | Smaller works listed by the municipality | Written declaration to the mayor | The period set by the municipal regulations (10 days in the model regulation) |
| Building permit | Construction, conversion, change of use, demolition, backfilling and excavation | Full application filed with the mayor | Wait for the written decision |
Each municipality applies its own building regulations. In 2023 the Ministry of Home Affairs proposed a model regulation (circular no. 2023-119): it only applies if your municipality has adopted it. Before any works, the municipality’s technical department will tell you free of charge which regime applies.
Which works need a permit and which are exempt
The same works can be exempt in one municipality and need a permit in another. The table compares the model regulation recommended in 2023 with the regulations of the City of Luxembourg (2018 version), two common benchmarks.
| Works | 2023 model regulation (if adopted) | City of Luxembourg (2018 regulations) |
|---|---|---|
| Garden shed, carport, greenhouse | Under 12 m²: exempt; 12 to 20 m²: declaration 10 days before | Permit for any new construction |
| Façade or roof repair or insulation, appearance unchanged, non-protected building | Exempt | Declaration; permit in a protected area |
| External wall insulation | Derogation possible up to 0.50 m on building lines, setbacks and heights | — |
| New openings in the façade | Under 5% of the façade: declaration | Changes to walls: permit |
| Solar panels | Exempt on non-protected buildings, balcony kits included | Roof panels listed among works requiring a permit |
| Outdoor unit of a heat pump or air conditioner | Not exempt; to be integrated into the building envelope, heat pump at least 2 m from the rear or side boundary | Permit likely on a façade |
| Interior works | Under 20 m² without touching the structure: exempt; 20 to 200 m²: declaration | Major interior maintenance: declaration |
| Demolition | 100 to 1,000 m³: declaration; above that: permit | Permit |
| Extension, raising the roof, conservatory, change of use | Permit | Permit |
Interior renovation that touches neither the structure, the façade, the roof nor the use of the building is generally exempt: kitchen, bathroom, floors, painting. Anything visible from outside, touching a load-bearing wall or creating floor space needs a declaration or a permit.
Preparing and filing the building permit application
The application is filed with the mayor of the municipality where the land is located, using the municipality’s form and a file whose exact content is set by its regulations. In practice, the plans are drawn up by an architect registered with the Order of Architects and Consulting Engineers (OAI); for small interior works, ask the municipality whether a simpler file is enough.
| Document | Content | For which projects |
|---|---|---|
| Municipal form and title deed | Applicant’s identity, land registry extract, any mandate | All applications |
| Location plan and site plan | Plot, setbacks and distances to boundaries, access | New build, extension, outbuilding |
| Floor plans, sections and elevations | Existing and proposed, use of rooms, heights | Any significant change |
| Photos and description | Current state, materials, colours, nature of works | Renovation, conversion |
| Energy performance certificate (calculation) | Required for a new build, an extension or a conversion subject to a permit | Except works on less than 10% of an element, or technical installations under €1,500 (house) |
Once the permit is granted, the mayor’s certificate must be posted where it is visible from the public road throughout the works; the municipality also publishes the decision. For a new build, the « as built » energy performance certificate is sent to the mayor within 2 months of final acceptance of the works.
Timescales, validity and appeals
No law sets a general processing deadline for the municipality. If the mayor has not decided within 3 months, the application may be considered refused (law of 7 November 1996, article 4), and that implicit refusal can be challenged. Once granted, the permit is valid for 2 years.
| Stage | Rule |
|---|---|
| Processing | No general statutory deadline; 3 months of silence = implicit refusal, which can be challenged |
| Validity | 2 years from the permit, plus a single one-year extension (law of 4 November 2024, in force since 11 November 2024; previously 1 year + twice 1 year) |
| Third-party appeals | 3 months from the permit being posted |
| Listed monument | Written authorisation from the Minister of Culture as well; with no reply within 4 months, the request is deemed approved |
Wait until the neighbours’ appeal period has expired before committing to irreversible spending, especially for an extension or a new build.
How much does a building permit cost?
The application itself costs little: any administrative fees are set by each municipality. The real cost is the file: architect’s plans, often €2,000 to €8,000 excluding VAT (renov.lu survey, September 2026) for a simple extension or conversion, and 8 to 15% of the cost of works for a full commission with site supervision; a structural study (€800 to €2,500 to open a load-bearing wall); and an energy performance certificate, whose price is not regulated (about €500 to €600 for a house). These fees are invoiced at 17% VAT. Details: architect fees.
Building a new house: what changes
A new build always needs a building permit, and the project must comply with the municipality’s general development plan (PAG) and the specific development plan (PAP, « new district » or « existing district ») covering the plot. The PAG sets the zoning, heights and setbacks; the PAP specifies building envelopes, materials and siting. Both can be consulted at the municipality and on the national geoportal.
- Plans and energy calculation: an architect’s file with the energy performance calculation; since 1 January 2023 the reference building is heated by a heat pump, which in practice rules out a fossil-fuel boiler in a new build.
- Plot: check the PAG and PAP before buying (buying a building plot).
- Demolish to rebuild: demolition is also subject to the permit regime (demolish and rebuild).
- VAT: building a home the owner will live in is invoiced at 3%, with no age condition, up to €50,000 of benefit (3% VAT).
Steps, timescales and budget for a whole project: our guide to building a house in Luxembourg.
Protected area, monument, green zone, co-ownership
Four situations add an authorisation or a vote to the municipal rule.
- Municipal protected area: façade or roof works that are normally exempt or declared may require a full permit, with requirements on materials and colours.
- Listed monument: written authorisation from the Minister of Culture (law of 25 February 2022), with support from the National Institute for Architectural Heritage; a grant can cover up to 50% of the costs for a listed building.
- Green zone: authorisation from the Minister for the Environment (amended law of 18 July 2018), filed with the Nature and Forest Agency.
- Co-ownership: works on common parts or the external appearance require a majority of the votes of all co-owners (article 16 of the law of 16 May 1975); other conversions, three quarters of the votes (works in a co-ownership).
For an outdoor air-conditioning or heat-pump unit, see also permits for an outdoor unit on a façade.
Reform under way: what is not yet in force
Bill 8480 provides for checking a complete file within 2 months, a decision within 4 months, one month for heat pumps and solar, « silence means consent » for solar up to 100 kW and national exemptions. It had not been passed by September 2026 (Council of State opinion of 17 July 2026). The tacit approval after one month for solar under the EU emergency regulation 2022/2577 was temporary: partly extended by Regulation (EU) 2024/223, it ceased to apply by 30 June 2025 at the latest. Ordinary law applies today.
Getting help with the file and the works
For an extension, a conversion or a new build, the architect designs the project, prepares plans that comply with the PAG and PAP and liaises with the municipality. Describe your project on our architect quote page; for exempt or declared works, request works quotes directly. To cost the whole project, see renovation cost per m².
Frequently asked questions about building permits in Luxembourg
Do I need a permit to insulate my façade from the outside?
It depends on your municipality. The model building regulation recommended to municipalities in 2023 (circular no. 2023-119) exempts from a permit the insulation of a façade without a significant change of appearance, outside protected buildings, and lets the insulation project up to 0.50 m beyond the building line, setbacks and heights; it only applies if the municipality has adopted it. In Luxembourg City, refurbishing a façade requires a declaration, and a permit in a protected area. Ask the municipal building department before ordering the works.
Do I need a permit to build a terrace in Luxembourg?
It depends on your municipality’s regulations. A ground-level terrace on the plot is often treated as minor outdoor works; a raised or covered terrace, one that involves backfilling or one close to the boundaries may need a declaration or a building permit. Ask the municipality’s technical department before ordering the works.
How long does the municipality have to reply?
There is no general statutory deadline. If the mayor has not decided within 3 months, the application may be considered refused, and that implicit refusal can be challenged. A complete file from the outset remains the best way to get a quick answer.
How long is a building permit valid?
Two years from issue, with a single extension of up to one year on request. This rule has applied since 11 November 2024; previously, a permit was valid for one year and could be extended twice.
Do solar panels need a permit?
The municipality decides. The 2023 model regulation exempts them on non-protected buildings, balcony kits included, but not every municipality has adopted it, and the City of Luxembourg lists roof panels among works requiring a permit. « Silence means consent » for solar has not yet been passed.
Do I need a permit to install an outdoor heat pump?
The outdoor unit is not among the exempt works in the model regulation: it must be integrated into the building envelope and, for an air-to-water heat pump, placed at least 2 m from the rear or side boundary. The same text sets a maximum noise level of 40 dB(A) at the boundary of the nearest buildable neighbouring plot. Check your municipality’s regulations.
What do I risk if I carry out works without a permit?
A stop-work order from the mayor and restoration at your own expense if the works cannot be regularised. Regularisation is only possible if the works comply with the PAG, the PAP and the building regulations. An irregularity also complicates selling the property.
Can my neighbour challenge my building permit?
Yes, for 3 months from the permit being posted, and it must remain visible from the public road during the works. Wait until this period is over before committing to major spending.
Plans, file, works
Architects and businesses established in Luxembourg price your project, permit included.