What makes a home truly comfortable? It's not just the aesthetic décor or modern amenities, but above all the comfort associated with daily use, such as proper soundproofing of the walls, optimal temperature and also - diffusely open walls. The latter may sound complicated, but don't worry, in today's post we will explain what it is and why it is so important.
Moisture in the walls can occur as a result of using wood that is too damp during the construction of the house or as a result of a naturally occurring physical phenomenon called the dew point, the direct cause of which is a temperature difference on both sides of the partition that promotes the accumulation of water molecules. Let's take a closer look at this process.
In cold air, the maximum possible vapour pressure is lower than in warm air. More water molecules can therefore be absorbed in the case of warm air. Water evaporates as the heat increases - the higher the air temperature, the more water molecules evaporate.
For any given temperature, air has a degree of saturation when it contains the maximum amount of water vapour it can hold at that temperature (i.e. the relative humidity is then 100%.). Above this temperature the water vapour becomes a liquid, i.e. condensation occurs. For a given temperature and volume of air, there is a maximum amount of water vapour at which the air becomes saturated and therefore water vapour will start to condense. This temperature is called the dew point temperature.
An example illustrating this element of physics is the so-called 'sweaty' windows in the house, which each of us has seen more than once. Exactly the same phenomenon occurs in walls, except that the accumulated water, with an ill-considered wall section, will not have a chance to evaporate.
However, you do not need to know or understand the physical phenomena. You do, however, need to be aware that the diffusion of water vapour can lead to the appearance of typical damp problems, i.e. rotting of the structure from the inside, resulting in the formation of mould and fungus, threatening the health of the occupants.
This is particularly the case with old-style constructions, where stone wool is used between the layers of OSB as thermal insulation. While stone wool offers little resistance to water molecules trying to escape, OSB has a high diffusion resistance, making this process more difficult.
The answer is modern construction, which is moving towards the use of materials with much better performance. Vapour-permeability is important in this respect, as is the proper arrangement of the boards and insulation layers, which will exclude the materials' resistance to water molecules moving through the structure. Proper ventilation and tightness of the thermal insulation is also important to prevent condensation from forming inside the walls.
In this way, diffusely open walls are created. The basic idea is to arrange the layers in such a way that the diffusion resistance decreases towards the external environment. The dew point, i.e. the condensation of water vapour, should occur as close as possible to the external part of the building wall. All this is done in order to, on the one hand, protect the structure from the effects of moisture and, on the other hand, to allow it to escape to the outside in a rapid manner that does not endanger the materials.
In WestaTre timber-framed modular houses, we apply this principle. On the inside, the first layer is a particularly important fireproof GKF board, followed by a 15 mm thick OSB layer. It has two functions: it stiffens the structure and acts as a vapour barrier, i.e. it stops water vapour from penetrating into the insulating layers of the wall. Thanks to the use of OSB inside instead of outside the partition structure, moisture does not penetrate inside the building, but is conducted outside.
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Enhanced strength and stability is provided by the Steico Joist I-beam construction, which in turn eliminates the occurrence of thermal bridges. An element that insulates rooms thermally and acoustically is also Steico Zell blown wood wool. This innovative material fills the spaces between the structural beams, ensuring the optimum temperature inside, regardless of the weather conditions outside.
In turn, Steico Universal insulation board is installed on the outside of the wall structure to protect the building from wind and water. It is waterproof and vapour-permeable, allowing water vapour to flow freely from within the envelope.
The result? A warm, isolated from external noises, safe interior that promotes the comfort of the whole family and also cares for their health.
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