Dryness – our trump card

There is an increasing demand for natural protection against algae and fungi on the facade without biocidal film preservative. The new StoSilco blue finishing render for the StoTherm Classic S1 non-combustible facade insulation system inhibits microorganisms from attacking by using natural principles that include optimising the water balance and reducing bioavailability. The system was honoured with the Blue Angel in recognition of its exceptional level of environmental compatibility.

Current scientific studies prove that the amount of biocidal film preservative washed off facades is nowhere near as high as was estimated in the past, and that these noticeably lower levels have been lowered further by the industrial encapsulation of the substances. However, there is a great demand for facade surfaces without film conservation. Sto has long been a leading manufacturer of coatings and has offered biocide-free facade products for many years. Nevertheless, if we always want to be able to offer our market partners the very best in technology, we cannot stop there – we must constantly develop our company and our product range. Therefore, in 2015, alongside the proven silicate products (StoSil OF and StoColor Sil), there will also be a high-quality silicone resin render without a biocide film: StoSilco blue. The new finishing render for the Blue Angel-certified StoTherm Classic S1 external wall insulation system (EWIS) is available in scratch render or modelling render versions. Just like the entire facade insulation system, it is non-combustible (A2, s1-d0) and free from solvents, mineral oils, and plasticisers. The genuine silicone resin render in accordance with DIN EN 15824 protects against algae and fungi using natural operating principles. The preventive and delaying inhibition of microorganisms is based on physical processes (water balance) as well as on aspects of bioavailability, and cannot be depleted.

Water is the crucial basis for life – including on the building envelope. As a result, we must ensure that the smallest possible amount of water reaches the facade and, if it does, it must be diverted away as quickly as possible. The risk of an algae or fungal attack drops considerably if there is no water on the system and, most importantly, if water does not accumulate in the system. In contrast to the hydrophilic absorbent renders, which can absorb up to 1.5 litres of water into the system in just two hours, StoSilco blue focuses on an optimised moisture balance which enables water to run off or dry as quickly as possible. Hardly any moisture is absorbed and no water is retained. It eliminates the need for long drying times for the facade, particularly on the side of a building exposed to weathering and in splash water zones. It also prevents harmful substances and dirt particles from being transported into the system and ensures that the durability of the finishing render is unimpaired. The binding agents and pigments in the render do not have to deal with wet and dry spells or periods of freeze and thaw.

The second basic requirement for microorganisms to live on facades is “bioavailability” or, in other words, the availability of nutrients. The natural protection provided by StoSilco blue also comes into effect here: firstly, the raw materials selected for the render are rarely available as nutrients for algae or fungi, and secondly, its maximum resistance to soiling also makes it difficult for nutrients from an external source to adhere to the facade.

StoSilco blue is highly water-repellent but still features excellent permeability for water vapour and CO2. The highly weather-resistant finishing render is applied with a square trowel or sprayed on wet. It has limited tintability in accordance with the StoColor System. Comprehensive sustainability data sheets, which summarise the ecological facts clearly and concisely, are available for all Sto systems and products that are offered without biocidal film preservative. This applies for both StoSilco blue and the proven silicate products that have made the technology leader from the Black Forest one of the largest suppliers of facade coatings without film preservative. It also applies for the StoTherm Classic S1 non-combustible EWIS, which has been recognised as a particularly environmentally-friendly system with its Blue Angel certification (RAL-UZ 140).

Source: Sto SE & Co. KGaA/sto.de