BREATHABILITY AND INSULATION
The cement and lime products used in the manufacture of mineral plasters are derived from limestone. The process by which these ingredients are produced involves the removal of water from the raw material so that when water is again added (to the plaster) these products, simply speaking, revert to their original rock-like nature. The other main ingredient of mineral plasters is sand. The very nature of pre-mixing mineral plasters in the factory allows for the selection and grouping of sands and aggregates of various grades and types in order to attain the ideal matrix required to suit the specific purpose of the plaster. All natural additives are incorporated into this basic plaster recipe according to the requirements of the plaster, which improve flexibility, water repellency, adhesion, strength, workability, the promotion of the hydration process etc. Putz-technik products ltd does not use any ingredient that will compromise the breathability (Water Vapour Diffusion Equivalent) of its products.
Breathability through the profile of any façade is essential for:
1. Durability
2. Insulation
Just as in the case of human skin, the breathability of plasters (or paint) is a function of pore structure. Likewise,
Putz-technik products ltd mineral plasters will repel liquid (water) while maintaining breathability.
Durability In some form or other, water is everywhere. All common wall construction materials, including kiln dried timber, contain and can absorb moisture. Air within wall cavities contains moisture. Water vapour will invariably migrate to where the temperature (air pressure) is lowest. In a wall, given that internal room temperatures are often higher than external temperatures, moisture will tend to migrate toward the external surface of the wall and, if possible, escape to the external environment. The action of such moisture, if trapped by a non-breathable membrane (e.g. acrylic paint or plaster) will, over time and changing internal/external temperature gradients, have a damaging effect on the façade and wall construction materials. Such damage is likely to include: paint blistering, cracking, delamination, dry rot etc. By allowing free movement of water vapour the durability, therefore, of both the cladding and construction material is significantly increased. Acrylic plasters and paints were intended to solve problems of adhesion and flexibility. They are, however, as time has proved, subject to a natural process of weathering which affects their flexibility, and hence, the life-span of such products. The adhesion of acrylic paints and plasters is in turn compromised due to their increasing brittleness and because of the moisture related problems described above. Mineral plasters do not lose flexibility over time. For this reason, and because they are gas permeable, adhesion is not compromised in this way. Mineral plasters can generally be expected to last as long and as well as the materials used in the wall construction. Silicone water soluble paints (Silco) can be expected to endure significantly longer than non-breathable paints. Silco will also significantly increase the life-span of the cladding and wall construction, as will SMK 1311 Masonry Water Repellent on pre-coloured plaster. Insulation If a building were to be renovated by plastering with mineral plasters on non-breathable painted walls inside and out, the average room temperature could be expected to rise by 2-4?C given standardized conditions (heating etc). Without the influence of non-breathable paints/plasters the average temperature rise would be further increased. It can be seen, then that plastering has an inherent insulation value, with an obvious saving of energy costs. Heat will naturally dissipate (i.e. move towards the cold). Heat will be more quickly dissipated in conditions of greater humidity (for example, if one’s clothes are damp). Locked-in dampness occurring in the construction of a wall will therefore reduce the average temperature of a room. Likewise, high room humidity will accelerate heat loss from the body. Mineral plaster technology is able to achieve a general lowering of both room and wall humidity by allowing a natural avenue of escape for moisture from the room and wall environments. |
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