The main feature of insulation, consisting of bonded mineral fibers - high air permeability. Straight through interfiber pores in the material is permeable to air, gaseous and liquid water, regardless of density Minplita . Some manufacturers believe most breathable mineral wool her dignity: fibrous insulation materials do not hinder the movement of steam out through the exterior walls. However, none SNIP does not permit the use of insulation and building envelope to dry indoor air exist for this ventilation system. In contact with cold external sites wet insulation inside the air condenses, wetting insulation. Limit moisture condensation in a heater can only design solutions, which reduce the diffusion and convective flow of incoming water.

Mineral wool insulation in roofing structures subject to strong operational impacts. Inside the fibrous structure, there are constant alternating processes: wetting-drying, freeze-thaw, mechanical vibration. Pulsation of air pressure in ventzazore (frequency of 0,2-1 Hz) due to a change of wind influence on the facade of a building causes vibration of the entire array of fibers. Filtration - air movement in the longitudinal and transverse directions within the mineral wool layer - also is associated with excessive pressure - discharge air ventzazore.

Durability - invariably insulating properties of mineral wool - depends primarily on the intensity of influencing factors. In the Russian climate the most destructive are the processes of freezing and thawing of wet rock wool. Rate of destruction of insulation depends on the volume of incoming and freezing of moisture.

Moisturize Minplita occurs from different sides, with hydrophobicity fiber insulation does not reduce the amount of moisture condenses.

Moisturize from the outside. Facade facing ventfasada consisting of separate elements, there is a gap through which rain and strong wind penetrate and moisturize the insulation system. From moisture is not fully protected even solid lining, because there is always the possibility of defects installation, mechanical damage, the number of which increases with the square facing, the number of window frames and various frames. In insulated sloping roofs over ventilated skate possible snow and rain. Condensate with a waterproofing underlay may be discharged to an open heater.

Moisturize from the inside. In cold weather insulation threatens wetting the warm side. If carriers have an increased water vapor permeability barriers (porous wall, brick wall with poor grouting, walling interpanel slots deficient vapor barrier attic), vaporous moisture from the living space is condensed in the cold regions insulation. Tall buildings have a high partial pressure of steam on the upper floors. In this case paroizoliruschey ability over fences, even made from cast concrete, may not be enough to have additional vapor barrier [1].

The combination of all factors in the long-term use leads to the fact that destroys organic binder, vibration fatigue failures exposed mineral fiber.

Recent domestic studies have shown that these factors can cause changes in linear dimensions, thermal conductivity, loosening, weakening and loss of mineral fibers.

The results obtained [2] indicate that: in a prolonged operation of the thermal conductivity of mineral wool slabs density of 74 kg / cu. m may be increased in 2,8 times, and the board density of 156 kg / cu. m - 1,9 times. The impact of blowing air flow rate of 0-0,7 m / s increases the thermal conductivity by 60%.

Issue - the loss of fiber mass - mineral wool density 74 kg / cu. m for 25 years, contingent reaches 18.78% of the initial mass and 3,32% for slabs density 156 kg / cu. m [3]. With respect to such ventfasadam weight loss rockwool slabs installed without wind-waterproof membrane, not only leads to a decrease in strength, insulating properties, but also a serious violation of ecology environment and living space. For example, if warming of a nine-building series of 90, with an area of ​​1,498 sq. warming. m required 135 cu. m modern mineral wool density 74 kg / cu. m. In the 25 years of conventional operation of a building ventilation air flows can endure because of skin venfasada 1,875 kg of fiber dust.

The above data suggest the feasibility of using the design of ventilated facades wind gidrozaschitnyh membranes on the outer surface of the mineral wool. More expensive solution - the use of panels of high density (above 150 kg / cu. M) does not provide similar protection to insulation from external humidification and filtration [4].

Guarantee the life of mineral wool 50 years can be subject to restrictions (rationing) of destructive factors. To this should be regulated by systemic protection insulation, working in an air gap of the facade or roof:

• protection of the inner surface of Minplita - rigid limitation of moisture from the premises provided a high level of vapor barrier fence;
• protection of the outer surface Minplita - strict limitation of atmospheric moisture, air filtration, the loss of mineral fibers is ensured by the wind gidrozaschitnoy diffusion membrane.

The traditional objection to the use of wind-gidrozaschitnyh membrane systems ventfasadov is that "the presence of water vapor permeability of the membrane reduces the thermal insulation system. However, calculations [5] show that the vapor permeable membrane slightly, by 0.5%, reduces the diffusion of water vapor through a multi-layer construction of the outer wall with ventilated air layer.

The fact that very often the fear vapor barrier installed in a residential area due to lack of ventilation systems. In this case, the fence in the insulation can act so much internal moisture from the living room, which can not cope membranes having water vapor permeability of more than 1000 g / sq. meters per day. As a result, this "economical" solution as a lack of ventilation in the room and the membrane ventzazore leads to internal moisture insulation and to eliminate its external security.

Air - a staple of human consumption, while at the same time, people - the main source of its pollution. The ventilation system should provide exactly the same way as other life-support systems: heating, sewerage, water, electricity.

When restricting entry of moisture from the premises membrane will display only the gaseous moisture that passes itself under adverse weather conditions - high humidity, fog and rain. Vapor permeability of 1000 g / sq. meters per day ensures that the heater in the equilibrium dry in any weather conditions.

Application of wind-gidrozaschinyh membranes and vapor barriers in the insulation systems with a ventilated gap will be excluded from the selection criteria insulation characteristics such as water absorption, air permeability, density, leaving only the thermal conductivity, dimensional stability, mechanical strength.

Source: Alexander Nelidov / company Tectothen GmbH metal magazine "The Evolution of the roof» / evoroof.ru

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