There are many good reasons for roof insulation. These are the three most frequently mentioned reasons why homeowners have their roof insulated:
Most roofs are insulated with mineral wool such as rock wool or clamping felt because those are easy materials to work with and adapt perfectly to the rafters. The insulation material is joint-tight and prevents unwanted thermal bridges. The choice primarily depends on the insulation method. All insulation materials are suitable for flat roof insulation, but glass wool, rock wool or cellulose are most commonly used. Wood fibre, polyurethane and XPS boards are most commonly used for above-rafter insulation, while insulation felt and insulation boards are used for below-rafter insulation. Mineral wool or rock wool mats are usually sufficient for floor insulation. In principle, all insulation materials insulate equally well, but of the more efficient insulation materials a fewer amount is required.
There are mineral, synthetic, mineral-synthetic, plant-based and animal-based insulating materials. They all have their advantages and disadvantages. It is best to consult a certified roofer from our professional partner network.
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Flat roof insulation is complex, but robust, resilient and weather-resistant. With a cold roof, the air circulates between the insulation layer and the roof cladding; with a warm roof, there is no air layer between the roof cladding and the insulation layer. Both methods insulate equally well. It is important that a so-called vapour barrier is laid to protect the insulation materials from moisture, for example from condensation. This applies to all insulation methods in this article.
In the case of over-rafter insulation, insulation materials are affixed to the roof beams externally. Typically, roofers need to cover the entire roof to accomplish this. Consequently, over-rafter insulation is a viable option only when there is a need for both insulation and roof renovation. While over-rafter insulation proves highly effective, allowing the living space to remain habitable during the process, it is essential to note that the associated work and, consequently, the costs for this insulation method are comparatively high.
Inter-rafter insulation is widely used because it is effective, simple and inexpensive. The diffusion-open underlay is laid on the rafters and the insulation material is clamped into the space between the rafters. In addition, insulation between the rafters is best suited if you want to convert the attic into a living space, as it fills the free space between the rafters. This preserves the entire living space in the attic.
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Under-rafter insulation alone is not adequate for effective insulation. Therefore, it is commonly paired with insulation between the rafters to improve its insulating effectiveness. This combination is particularly useful, for instance, when the attic is being renovated or when over-rafter insulation proves too costly. On its own, under-rafter insulation lacks sufficient effectiveness, making it an impractical method for roof insulation, as the insulation value can only be enhanced to a certain extent.
Floor-ceiling insulation is especially suitable when the attic is not intended for use as additional living space. It represents the simplest and most cost-effective insulation method, with the insulating materials laid on the ceiling of the top floor, resembling a floor. During the planning phase, a choice is made between a walk-in and a non-walk-in variant. Since the loft is not utilized and doesn't require heating, floor-ceiling insulation results in cost savings on heating expenses.
The costs depend on the roof area to be insulated, the insulation method and the insulation material. The cheapest method is to insulate the floor area, the most expensive is to insulate the rafters. For an average single-family home, you can estimate 4,000 to 8,000 francs for insulation of the floor area, 7,500 to 15,000 francs for insulation below the rafters, 18,000 to 27,000 francs for insulation between the rafters and 27,000 to 45,000 francs for insulation above the rafters. The cost of a flat roof insulation varies from simple to complex, which is why the approximate costs are between 3,000 and 20,000 francs. It is best to obtain quotes from certified roofers and compare prices, services and additional costs.
The easiest way to apply for subsidies for energy-efficient renovations is online via the website of the Swiss Buildings Programme. If you click on your canton of residence on the homepage, you will be taken to the details page. There you will find detailed information, can download documents and submit your application. To apply, you will need a renovation plan, which you must submit together with the subsidy application.
In addition to investment grants, some cantons also offer tax relief for energy-saving measures. Ask the tax administration what applies in your canton of residence.
More and more banks are financing renovations, conversions and energy-saving measures such as roof insulation with low-interest mortgages. Ask your bank advisor for more details.
