Two quotes for PIR boards may cover a seemingly similar material but in practice a different scope. Before comparing price, it is worth checking the construction, format and documentation. It also matters how much of the product will actually end up in the building element. Only such a set allows you to assess the purchase cost. A PIR board has a factory-formed core of rigid polyisocyanurate foam. The closed-cell structure helps to limit heat conduction. However, the parameters also depend on the formulation, thickness and facing. You must not attribute the values from one selected catalogue to all boards. The commercial description should state the exact type of finished product. Polyurethane foam alone does not define the facing, edges or intended use.

The PIR format affects the number of joints, ease of working and the amount of offcuts. A small board can make it easier to insulate reveals, while a large one can speed up covering a regular surface. However, dimensions must be checked for the specific variant and edge profile. The nominal rectangle area is not always equal to the effective coverage area. Within insulation board families, 1200 × 600 mm and 1200 × 2400 mm are found among others. This does not mean that every type of facing is available in both dimensions. A composite board with gypsum may have a different format, for example 1200 × 2600 mm. Information about the dimension must therefore accompany the full product description.

The insulation thickness is not chosen on the basis of the term "ceramic hollow block" alone. The type of masonry, the mortar and the type of façade finish all matter. In a new house, it is worth combining the choice of PIR with the design of the windows, ring beams and plinth. The favourable calculation result will then also cover the places where different parts of the building meet. Two blocks of the same width can form walls with different thermal resistance. Geometry, material, the arrangement of the voids and the method of bricklaying all count. The parameters selected for the calculations must correspond to the adopted technology. They must not be replaced with the best lambda found for the entire product family.

The PIR thickness calculator is useful for comparing options if it describes the wall you actually intend to build. The most common mistakes concern units, the properties of the masonry and omitting the facings. It is worth treating the calculation as the first stage of selection and then checking moisture, junctions and the compliance of the whole solution. Entering a random U-value into the form can lead to choosing insulation that is too thin or unnecessarily thick. The target follows from the function of the building, the operating temperature and the adopted requirements. A wall in a flat is analysed differently from a partition between a warm workshop and a cool store.