EU Guidance Paper F concerning the Construction Products Regulation (CPR) defines durability as follows: “The durability of a product is the ability of the product to maintain its required performance over a given or long time, under the influence of foreseeable actions. Subject to normal maintenance, a product shall enable a properly designed and executed works to fulfil the Basic Works Requirements for an economically reasonable period of time.”

Durability is thus dependent on the intended use of the product and its service conditions. The assessment of durability can relate to the product as a whole or to its performance characteristics, insofar as these play a significant part with respect to the fulfilment of the Basic Works Requirements. In either case, the underlying assumption is that the performance of the product will be maintained at an acceptable level, in relation to its initial performance, throughout its working life.


Ageing refers to long-term slow change of properties over time. High moisture content and high temperature acting at the same time can affect the mechanical properties of mineral wool. A degradation effect can thus been seen and measured in the strength properties during such extreme conditions.

Dimensional stability under load, temperature and humidity exposure

Dimensional stability means that material keeps its original size and thickness over time. This property is tested according to EN 1604 (testing: 48 h in 23°C, 90 % humidity; allowed change max. 1 %).

Dimensional stability is important for the insulated structure to function properly over time. Requirements are set either on dimensional stability at a constant temperature (EN 1604) or stability under temperature and humidity cycle (EN 1603). For a loaded structure, it is also important to choose an insulation product with good long-term thickness stability (EN 1606).

Dimensional changes in materials are caused by their thermal expansion coefficients. This is the rate at which materials shrink or expand when they are cooled down or heated. Practically all materials have an expansion coefficient that is dependent on the chemical composition of the material.

Stone wool is inorganic material and it keeps it shape and dimensions in all conditions.

Resistance against alkalinity and chemicals

Insulation products should be specified to be compatible with other products in the structure. They should be resistant to alkalinity if they are in contact with concrete and to all chemicals which are used for water proofing, gluing, etc.

Alkaline resistance is an extremely important property for the insulation materials used in thin rendering applications where rendering has been applied directly to the surface of the insulation.

  • Stone wool is highly alkaline resistant 

UV radiation during installation

During the construction process insulation products are exposed to ultraviolet radiation. A typical case is the ETICS in which the facade of a building is first insulated leaving the insulation surface exposed. The rendering is then applied within a specified time frame. It is necessary for the insulation to withstand UV exposure without degradation.

In the table below, the standard test methods of durability are presented.

Property  Standard test method  Mineral wool insulation In-situ blown insulation 
Dimensional stability at constant temperature
Dimensional stability under temperature and humidity
Long-term thickness stability
Chemical resistance
   x  x
UV radiation
Durability for sandwich panels
EN 14509