In Switzerland, a complete roof refurbishment generally costs between 20,000 and 50,000 CHF for a house, or around 500 CHF per m² including the underlay. Insulating just the loft floor is much cheaper: around 60 CHF per m². The roof accounts for around 21 per cent of heat loss from a poorly insulated house: this is often one of the most cost-effective improvements.
How much does a roof renovation cost?
| Work | Approximate price |
|---|---|
| Insulation of the floor in an inaccessible loft | approx. 60 CHF/m² |
| Insulation of the floor in an accessible loft | approx. 150 CHF/m² |
| Insulation between rafters or on a flat roof | approx. 210 CHF/m² |
| Complete refurbishment, including underlay | approx. 500 CHF/m² |
| Complete renovation of a house | approx. 20,000 to 50,000 CHF |
Sources: Canton of Valais and Neho. Costs vary significantly depending on the shape of the roof, access, scaffolding and the canton: only quotes are binding.
What’s the right solution for your roof?
The loft is not lived in
Insulate the loft floor: this is the cheapest option. If you want to continue walking on it or storing things there, rigid panels or a floorboard are laid on top of the insulation.
The loft is lived in
- Insulation between the rafters, from the inside: cheaper, without touching the roof covering.
- Insulation on top of the rafters: the best solution when the roof covering needs replacing, as it eliminates almost all thermal bridges.
The roof is flat
Waterproofing and rainwater drainage require particular attention. Always consult a flat-roof specialist.
What level of performance should you aim for?
Performance is measured by the U-value: the lower it is, the better the roof insulates.
| Level | U-value | Note |
|---|---|---|
| Legal minimum | 0.25 W/m²K maximum | No grant |
| Recommended | 0.20 W/m²K | Condition for the cantonal grant |
| Exemplary | approx. 0.15 W/m²K | Higher grant, ideal for a complete refurbishment |
Example: on a roof built in 1985 with 6 cm of insulation, adding approximately 14 cm of high-performance insulation allows a U-value of 0.20 to be achieved (Canton of Valais).
If you are uncovering an entire section of the roof, the Energy Act often requires you to generate your own electricity, for example using solar panels. Plan for these right from the start of the project.
Grants
Roof insulation is subsidised under the Buildings Programme, provided you achieve a U-value of at least 0.20. For example:
- Vaud: 40 CHF/m² (U ≤ 0.20), 70 CHF/m² (U ≤ 0.15), and 100 CHF/m² if you install solar panels (Vaud).
- Geneva: 140 CHF/m² for elements in contact with the outside (U < 0.2) (Geneva).
Applications for insulation grants must be made before work begins. For solar panels, the one-off payment from Pronovo must be applied for after the system has been commissioned.
See the grants available in your canton →
The stages of a roof renovation
- Have the roof assessed by a specialist: roofing, waterproofing, roof structure, existing insulation.
- Compare the options: insulation from above or below, choice of insulation material, vapour barrier, costs and timeframes.
- Obtain planning permission from the local council if the appearance of the roof will change.
- Submit the grant application before work begins.
- Carry out the work, ideally including solar panels and the façade if scaffolding is erected.
- Apply for the grant payment, providing supporting documents.
