What foam thickness should I use?

Important changes aimed at the development of energy-efficient construction are regularly introduced to Polish regulations on the construction of houses.
The new regulations are primarily concerned with a gradual reduction of the heat transfer coefficient for the building envelope, which will reduce energy demand.
Thanks to these legal standards, newly built houses are more energy-efficient and help their owners to save money.
According to the current regulations, the heat transfer coefficient for roofs and flat roofs must be a maximum of U=0.18, and from 2021 – U=0.15, which in the case of utility attics means that an open-cell PUR layer with a thickness of 20 and 24 cm respectively must be used.

Regardless of the thickness, it is recommended that the wooden structure be insulated starting from the front of the rafters in order to ensure the continuity and seamless insulation of the entire roof.

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