A wall made of ceramic hollow blocks does not have a single fixed thermal performance. Thicknesses, the arrangement of voids, mortars and the condition of the existing masonry all vary. When choosing PIR, it is worth starting from this data and then looking at the windows, the plinth and the junction with the roof. A good insulation thickness must suit the whole house, including places that are not visible on a simple elevation. The name of the material alone is not enough for calculations. The wall thickness and the thermal conductivity value specific to the given arrangement are needed. In an existing house, it is worth checking the documentation, the wall at an opening or a safely made inspection opening. One should not choose the best parameter from among all available hollow blocks.

The PIR thickness calculator is useful when it compares a known wall build-up with a specific board. It will not detect a hidden cavity, damp plaster or a thermal bridge at the ceiling. Treat it as a tool for organising options. Before you start calculating, note the wall build-up and the effect you want to achieve in the room, studio or small premises. You need the thicknesses of the layers and their thermal properties. If the calculator lets you choose a material from a list, check that the selected item matches the actual masonry. A hollow block with a similar name may have a different construction. In an older premises, it is worth filling in the missing information before buying insulation.

Aerated concrete can form a warm wall, but its properties depend on the grade and thickness. When planning a PIR façade under render, you need to check both the thermal result and the compatibility of the whole system. Moisture in new masonry, substrate adhesion and fixings suited to the lightweight wall material are separately important. A general phrase 'aerated concrete' is not entered into the calculations. You need the correct thermal conductivity value for the grade used and the design conditions. Masonry of the same thickness can have different insulation performance. Joints and local reinforced concrete elements also matter.

A short white PIR wall board 100 mm can be convenient when partitioning a back room or a small workshop. However, colour and dimension alone do not determine suitability. The 2480 mm length must be compared with the actual installation height, and second grade with the description of the specific defect. An offer labelled in this way requires several separate checks. Start with a section through the floor, wall and ceiling. The usable height depends on finish levels, construction and how the panel is closed at the top and bottom. A 2480 mm length does not promise a room of exactly that height. Do not order quantities based solely on a measurement from the raw floor to the ceiling.