Should you renovate before renting out? Cost/benefit analysis
Which renovation works are profitable before letting in Belgium? Impact on EPC, rent and vacancy. Return on investment calculation.
Renovate or let as is: a strategic choice
The question faces every landlord preparing to let their property: should you invest in works or offer the property as it stands? The answer depends on three factors — the current EPC score, the local rental market conditions and the available budget.
In Belgium, energy obligations are becoming stricter year after year. Since 2023 in Brussels and 2025 in Wallonia, properties with a poor EPC certificate face restrictions on rent indexation. A poorly insulated property can therefore lose rental value over time, quite apart from the longer vacancy period it generates.
All three Belgian regions impose safety, sanitation and habitability standards. A non-compliant property can be banned from letting by the regional inspectorate, with fines of up to 25,000 EUR in Brussels.
To make an informed decision, you need to compare the cost of works against the potential gain: rent increase, reduced vacancy and retention of the right to indexation. That is exactly what this guide proposes.
The most profitable works before letting
Not all works are equal. Some generate a rapid return on investment, others are purely cosmetic and do not justify the expenditure.
High-impact works
| Works | Average cost | Estimated rental gain | Payback |
|---|---|---|---|
| Roof insulation | 8,000 - 15,000 EUR | +80 to 120 EUR/month | 4 - 6 years |
| Window replacement | 6,000 - 12,000 EUR | +50 to 90 EUR/month | 5 - 7 years |
| Condensing boiler | 4,000 - 7,000 EUR | +30 to 60 EUR/month | 5 - 8 years |
| Modern bathroom | 5,000 - 10,000 EUR | +40 to 80 EUR/month | 5 - 7 years |
Works to avoid
Luxury renovations (marble, high-end home automation, jacuzzi) are virtually never recouped on the standard rental market. The average tenant values energy efficiency, cleanliness and functionality, not high-end finishes.
Renovation works in a property over 10 years old benefit from the reduced VAT rate of 6% instead of 21%. This 15-point saving considerably improves the return on investment. Check the conditions with the FPS Finance.
A refresh (painting, professional cleaning, minor repairs) for 2,000 to 4,000 EUR is often the best value for money: it reduces vacancy without a heavy investment.
The direct impact of the EPC on profitability
The EPC (Energy Performance Certificate) has become a determining criterion for letting in Belgium. Its influence operates on three levels.
Rent indexation
Since 2023, properties rated E, F or G in Brussels can no longer have their rent indexed. In Wallonia, labels F and G have been affected since 2025. In Flanders, similar restrictions are being progressively introduced. In concrete terms, an F-rated property that can no longer be indexed loses on average 2 to 3% of rental value per year.
Property attractiveness
Tenants now compare estimated energy charges before signing. A well-insulated property (class A, B or C) lets on average twice as fast as one rated E or F, according to BNP Paribas Real Estate figures (2025).
Grants and subsidies
All three regions offer grants for energy improvement works. In Brussels, Renolution grants cover up to 70% of insulation costs for low incomes. In Wallonia, the PACE programme offers interest-free loans. These subsidies considerably reduce the net cost of renovation.
For more on the link between EPC and indexation, see our EPC guide and indexation ban.
Calculating return on investment
The calculation is simple: divide the net cost of works (after grants) by the net monthly gain (rent increase + vacancy savings).
Concrete example
A landlord owns a 2-bedroom flat in Brussels, currently rated E, let at 850 EUR/month. They invest 18,000 EUR in roof insulation and window replacement. After Renolution grants (4,500 EUR), the net cost is 13,500 EUR.
The property moves to class C. The rent rises to 950 EUR/month (+100 EUR) and the vacancy period drops from 2 months to 2 weeks. The annual gain is 1,200 EUR (rent) + 1,425 EUR (reduced vacancy) = 2,625 EUR. The payback is 5.1 years.
Calculation pitfalls
- Not counting grants: they significantly reduce the actual cost
- Forgetting vacancy: one month of vacancy at 900 EUR costs more than a 3,000 EUR refresh
- Ignoring property tax: certain renovations (solar panels in Wallonia) qualify for temporary reductions
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Conclusion: renovate yes, but in a targeted way
Renovation before letting is not always necessary, but it is often profitable when it targets the right items. The golden rule: prioritise energy efficiency (insulation, windows, boiler) and basic comfort (bathroom, kitchen), taking advantage of regional grants and the 6% VAT rate.
Key points to remember:
- The EPC determines indexation — a poor score costs dearly in the long term
- Roof insulation offers the best return on investment
- Regional grants reduce the net cost by 20 to 70%
- A simple refresh may suffice if the EPC is acceptable
- Rental vacancy is the most underestimated hidden cost
Before launching works, have an energy audit carried out to identify the priority interventions and calculate the ROI of each item.
Frequently asked questions
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For a 70 m2 flat, expect between 15,000 and 40,000 EUR depending on the extent of the works. A light energy renovation (roof insulation, window replacement) costs on average 20,000 EUR and can gain 2 to 3 EPC classes.
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No, but the property must meet the minimum safety, sanitation and habitability standards of the region. In Brussels, an EPC certificate is mandatory and properties rated F or G can no longer be indexed. Similar obligations exist in Wallonia and Flanders.
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On average, a targeted renovation pays for itself in 5 to 8 years through the rent increase and reduced vacancy. Roof insulation offers the best cost/benefit ratio with a payback in 4 to 6 years.
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