A suitable panel with mineral wool must match the wall's function, the structure and the interior conditions. Thickness is only one of the criteria. Thermal insulation, fire requirements and load-bearing capacity are checked separately. It is worth confirming these data before installing the framework. Changing the panel later may entail further changes. Start with how the building will be used. Determine the temperature, humidity and type of activity. Then define the wall's role: external cladding, internal partition or part of a solution with a required fire resistance. Each of these functions leads to a different set of criteria.

Outlet stock can help reduce the cost of the building envelope if the available batch suits the project. First, cosmetic defects must be separated from damage that affects how the panel performs. Then lengths and joints should be compared. In staged extensions, it is particularly important to be able to assemble a complete wall from matching components. Outlet is a commercial term that does not describe one fixed list of defects. A price reduction may be due to a scratch, a different shade, an unusual length or a leftover from an order. It may also be due to more serious damage. It is therefore necessary to obtain a description of the specific pieces, not just an assurance that the panels are ‘almost new’.

A thickness of 100 mm is a good point of comparison across different mineral wool panel families. However, it does not mean a single set of properties. Uc, mass, fixing and classifications may differ. Before purchase, product data must be combined with the wall design. This is particularly important when substituting material in an already planned project. An example wall variant with a mineral core and 0.5/0.5 mm facings has a Uc of approximately 0.39 W/(m²K) and a mass of 18.1 kg/m². A lighter variant of the same thickness may have a Uc of 0.38 W/(m²K) and a mass of 16.6 kg/m². These are two specific solutions, not a range guaranteed for every 100 mm panel.