Important: A certain insulation value is prescribed by law. The so-called U-value for thermal transmittance must not exceed 0.24 watts per square meter and Kelvin. A U-value of 0.24 usually corresponds to around 18 cm of insulation thickness. This is the minimum value. If you insulate thicker, you can count on government subsidies.
With a pitched roof, a U-value of 0.14 is sufficient to apply for KfW funding. Since 2020, this support has been approximately twice as high as in previous years. If the owner combines several different renovation measures, the state increases the subsidy again. A clever approach is worth cash money here. A prerequisite for KfW funding is that a building energy consultant plans the insulation or renovation from the beginning and confirms it in writing at the end. This energy advisor must be on the federal energy efficiency expert list or no funding is available.
Conclusion: A professional roof insulation is carried out in a few days, a threatening penalty is avoided under certain circumstances and the expenses for the insulation are amortized with subsidies after approximately 6 to 20 years.
