Home Extension Quote in Luxembourg
Compare up to 3 quotes from specialised companies for your home extension, loft conversion or addition in Luxembourg. Free, no commitment, response within 48h.
Horizontal extension vs Loft conversion: which to choose in Luxembourg?
This is the first question to consider. The choice depends on your plot, the existing structure of your home and your budget.
Ideal if you have space on your plot. Built at ground level, attaching a new structure to the existing house.
- From €2,500/m² (timber frame) to €4,500/m² (concrete/steel)
- Construction time: 2 to 4 months
- No structural study of the existing house required
- Ideal for: bedroom, office, living room, conservatory
- The most common and least expensive option
The solution when the plot is too small to extend sideways. A new storey or attic is built on top of the existing structure.
- From €3,500/m² to €6,000/m² depending on structure
- Construction time: 3 to 6 months
- Foundation solidity study required
- Ideal for: full storey, attic, duplex
- 30 to 50% more expensive than a horizontal extension
If you have enough space on your plot, a horizontal extension nearly always offers the best value in Luxembourg. It requires less structural work, is faster to complete and costs less. For smaller plots, building upward is a worthwhile investment given Luxembourg property prices. An expert will assess feasibility during a free visit.
Types of structures for your extension
| Structure | Avg. price/m² | Build time | Advantages | Limitations |
|---|---|---|---|---|
| Timber frame | €2,500 – €3,500 | 2 to 3 months | Quick, eco-friendly, good thermal insulation | Regular wood maintenance |
| Masonry / Concrete | €3,500 – €4,500 | 3 to 5 months | Very robust, durable, continuity with existing building | Longer, more expensive, heavier site |
| Steel and glass | €4,500 – €6,500 | 3 to 5 months | Modern design, exceptional natural light | High cost, acoustic insulation needs attention |
| Modular construction | €2,200 – €3,000 | 1 to 2 months | Very fast (prefabricated), minimal disruption | Limited customisation, ground space required |
Indicative prices for Luxembourg — 2026. Rates vary by project complexity, finishes and location.
Some companies in Luxembourg charge up to €7,000 – €8,000/m² for a concrete extension: well above the national average. Always compare multiple quotes and benchmark prices against market averages.
Home extension prices in Luxembourg in 2026
The prices below include structural work, insulation, plumbing, electrics, floors and walls — a turnkey project. On average, expect 60% structural and main works, 40% finishing and fit-out.
| Project type | Avg. price/m² | Example 30 m² | Duration |
|---|---|---|---|
| Horizontal extension — Timber frame | €2,500 – €3,500 | €75,000 – €105,000 | 2 to 3 months |
| Horizontal extension — Concrete | €3,500 – €4,500 | €105,000 – €135,000 | 3 to 5 months |
| Loft conversion / Storey addition | €3,500 – €6,000 | €105,000 – €180,000 | 3 to 6 months |
| Conservatory / Glass extension | €4,500 – €6,500 | €135,000 – €195,000 | 3 to 5 months |
Prices collected from partner companies in Luxembourg — 2026. Rates vary by finishes, complexity and location.
ROI: why an extension is a highly profitable investment in Luxembourg
With an average property price of €8,373/m² in Luxembourg (source: Immotop.lu, Q1 2025), every square metre added significantly increases your property’s value — often for a cost well below the market price.
| Example | Extension cost | Value added to property | Net gain |
|---|---|---|---|
| Timber extension 20 m² | €60,000 | ~€167,000 | +€107,000 |
| Concrete extension 30 m² | €120,000 | ~€251,000 | +€131,000 |
| Storey addition 40 m² | €200,000 | ~€335,000 | +€135,000 |
Calculations based on the national average of €8,373/m² (Immotop.lu, Q1 2025). In the Centre region (Luxembourg City), prices reach €12,106/m², making the investment even more profitable.
Properties rated A to C sell for up to €1,400/m² more than those rated F to G in Luxembourg. By using your extension to improve overall energy performance (enhanced insulation, triple glazing, ventilation), you further increase your property’s value.
How much would your extension cost?
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Get my free quotes →3% VAT and financial grants for your extension in Luxembourg 2026
Unlike heat pumps or solar panels, home extensions don’t directly benefit from Klimabonus. However, the super-reduced 3% VAT represents a major financial advantage, and you can combine grants if your extension includes energy efficiency works.
Super-reduced 3% VAT — saving ~14% on total cost
The standard VAT rate in Luxembourg is 17%. For construction and renovation works on a property used as the main residence, the state applies a reduced rate of 3%. On a €120,000 extension (excl. VAT), this saves approximately €16,800 compared to the standard rate. The tax benefit is capped at €50,000 per dwelling created or renovated.
Klimabonus — if insulation and energy performance are included
If your extension includes high-performance insulation (walls, roof, triple glazing) meeting Klimabonus standards, you can claim grants for the energy component of the project. Amounts vary depending on the works carried out. Your construction company will guide you through the process.
Mandatory energy passport
In Luxembourg, an energy passport is mandatory for all extensions (Grand-Ducal regulation of 9 June 2021). Your extension must meet current energy performance standards. This is an opportunity to optimise your project and maximise your grants.
Municipal grants — vary by commune
Some Luxembourg municipalities offer additional grants for construction or renovation projects. Check with your local authority for details.
Use your extension project as an opportunity for a comprehensive energy renovation: insulate existing walls, replace the boiler with a heat pump, install solar panels. Combined grants (Klimabonus + Enoprimes + 3% VAT) can then reach tens of thousands of euros.
Administrative steps for an extension in Luxembourg
Any home extension in Luxembourg requires a building permit issued by the mayor of your municipality. Plans must be drawn up by an architect registered with the OAI.
Check feasibility against the PAG
The General Development Plan (PAG) of your municipality defines buildable zones, permitted heights, minimum distances from property boundaries and planning rules. Check with your local authority or the national Geoportal to see what is allowed on your plot.
Engage an architect and prepare plans
The architect draws up plans compliant with the PAG and building regulations, including the mandatory energy passport for your extension. Expect 8 to 12% of the construction cost for architect’s fees.
Submit the building permit application
The complete file is submitted to the mayor. Processing times vary by municipality: allow on average 4 to 12 weeks. The permit is valid for 2 years. Additional authorisations may be needed (water services, environment, etc.).
Apply for 3% VAT
Before works begin, obtain approval from the AEDT (tax authority) to benefit from the reduced rate. Your construction company can handle this for you.
From finding an architect to obtaining the building permit and reduced VAT — our partner companies guide you through all these steps free of charge.
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Get my quotes →How does a home extension project work in Luxembourg?
Technical visit and site assessment
The company visits to assess site constraints (slope, access, foundation depth). For a loft conversion, an engineer checks the existing structure’s solidity. This first step is usually free and without commitment.
Design, plans and permits
The architect designs plans, prepares the energy passport and submits the file to the municipality. You approve plans, choose materials and finishes. The company prepares the 3% VAT application. Duration: 2 to 3 months.
Site preparation and foundations
Earthworks, foundation pouring, connection to existing utilities (water, electricity, drainage). For timber frame extensions, panels are prefabricated in the workshop during this phase. Duration: 2 to 4 weeks.
Main structure construction
Assembly of the structure (walls, roof frame, roofing), insulation and exterior joinery (windows, doors). The extension is made weathertight. Duration: 4 to 8 weeks depending on size and structure type.
Fit-out and finishing
Plumbing, electrics, heating, flooring, painting, connection to the existing house. The opening between the extension and the house is created at this stage. Duration: 3 to 6 weeks.
Handover and completion
Final inspection of all works, airtightness and compliance tests. You receive the definitive « as-built » energy passport, to be submitted to the municipality within 2 months of completion.
How to choose the right company for your extension in Luxembourg?
At least 10 to 20 years’ experience in complex construction projects in Luxembourg. An established company will still be around in 10 years to honour its warranty.
Prices in line with Luxembourg averages. Be wary of quotes above €5,000/m² for a standard concrete extension. Always compare at least 2 to 3 quotes.
Decennial warranty and insurance. Check the company offers a multi-year construction warranty and professional liability insurance.
Full site coordination. An extension involves many trades (masonry, carpentry, roofing, insulation, plumbing, electrics, heating, joinery). Choose a company that coordinates everything.
Administrative support. The best companies help you with all the paperwork: finding an architect, building permit, 3% VAT application, energy passport.
In Luxembourg, price isn’t the only factor. A poorly built extension can be very expensive to fix and devalue your property. Pay attention to material quality, planning reliability and the company’s references.
FAQ — Frequently asked questions about home extensions in Luxembourg
How much does a home extension cost in Luxembourg in 2026?
Prices vary by structure type and size. On average, expect €2,500 to €3,500/m² for a timber frame extension, €3,500 to €4,500/m² for concrete, and €3,500 to €6,000/m² for a loft conversion. A 30 m² extension therefore costs between €75,000 and €180,000 all-inclusive. The 3% VAT rate (instead of 17%) provides a substantial saving on the total cost.
Do I need a building permit for an extension in Luxembourg?
Yes, any home extension requires a building permit issued by the mayor of your municipality. Plans must be drawn up by an architect registered with the OAI. The extension must comply with the General Development Plan (PAG): buildable zones, heights, distances from property boundaries. An energy passport is also mandatory for all extensions.
What financial grants are available for an extension in Luxembourg in 2026?
The main benefit is the super-reduced 3% VAT (instead of 17%), applicable to construction works on your main residence. On a €120,000 extension (excl. VAT), this saves approximately €16,800. If your extension includes energy improvement works (high-performance insulation, triple glazing), you may also qualify for Klimabonus grants for that part. Some municipalities offer additional grants.
How long does an extension project take?
Allow 2 to 3 months for the administrative phase (plans, permits). Then, construction itself takes 2 to 5 months for a horizontal extension, and 3 to 6 months for a loft conversion. In total, from first meeting to move-in, plan for 5 to 9 months. Timber frame extensions are quicker, as panels are prefabricated in a workshop.
Horizontal extension or loft conversion: which to choose?
If you have space on your plot, a horizontal extension is simpler, faster and 30 to 50% cheaper than a loft conversion. Building upward is the solution when the plot is too small. It requires a foundation solidity study and costs more, but doesn’t encroach on your garden. A professional will assess the best option during a free visit.
What is the return on investment for an extension in Luxembourg?
Highly profitable. With an average property price of €8,373/m² in Luxembourg, an extension at €3,500/m² costs less than half the property price per square metre. A 30 m² extension can add approximately €250,000 to your property’s value, for an investment of €105,000 to €135,000. In the Centre region (Luxembourg City), where prices exceed €12,000/m², the ROI is even greater.
Is an energy passport required for an extension?
Yes. Since the Grand-Ducal regulation of 9 June 2021, an energy passport is mandatory for all building extensions in Luxembourg. It must be submitted with the building permit application. An « as-built » passport must be delivered to the municipality within 2 months of project completion.