MANUAL

Roof membranes

Highly vapour-permeable membranes are used as an initial covering of sloping, ventilated roofing. They are of low diffusive resistance and ensure carrying of vapour to the outside. In order to function well as an initial covering they have to ensure durability and protection against the column of water.

Vapour-insulating membranes

Vapour-insulating membranes, also called vapour-insulations, vapour retarders, vapour barriers etc. Based on vapour-permeable fibres they are a modern method for forming the protection of thermo-insulation against moisture coming from attic interior. They are distinguished by around tenfold higher vapour-permeability in comparison to common vapour-insulations PE and around tenfold lower vapour-permeability in comparison to low vapour-permeable roof foils. Such material specificity enables harmonious cooperation with highly vapour-permeable membrane. Thanks to low diffusive resistance of membrane the diffusion of material used as a vapour-insulation also may be enlarged.

Excessive air humidity

Owing to this fact one can avoid excessive air humidity inside the building that was found in attics in the eighties and nineties of the last century. House hermeticism which is the effect of new technologies development in window frames has resulted in problems with increase of dampness in interior and consequently the problem of moulds. Low quality of gravity ventilation (ineffective in new conditions) has become visible. The increase of moisture in interiors and use of highly vapour-permeable materials as an initial roofing have enabled unsealing of attic and using of so-called active vapour-insulations that allow larger quantities of vapour to evaporate through roof barrier. It wasn’t the only element of battle against the excessive air humidity. People started to become interested in effectiveness of ventilation systems, the window producers have started to launch elements that would improve ventilation such as window ventilators, window micro-openers etc. Houses and attics have become more diffusive active and consequently they have started to ensure healthy atmosphere.

Nowadays active vapour-insulations are commonly used, their price difference in comparison to traditional vapour-insulations is compensated by the benefits of their use.

Wind-insulating membranes

Wind insulations are mainly used in external building walls in the skeletal building structure (timber and steel), beam houses (internal walls), elevations of building insulated with wool (outside), in the ventilated elevations systems (e.g. stone), under siding (timbered, PVC, made of wool fibres etc.) including use of abovementioned technologies in attics. They enable vapour diffusion from thermal insulation and building walls and protect the walls from moisture. Thanks to this function they prevent buildings from cooling maintaining their high thermal parameters. They effectively prevent from gathering of moisture in walls and thermo-insulation, permanent dampness of walls and the lowering of thermal parameters of building. They also effectively protect from uncontrolled air flow from outside (that significantly increases heat losses).

The use of wind-insulating membrane on roof is justified only when it is used as a wind insulation of wall surface, insulation of roof and sloping attic thermal-insulation – ensuring of final roofing is needed in advance. Wind-insulating membranes are made of vapour-permeable materials – usually these are the single-layered fibres. They have extreme vapour-permeability factors and should be stabilised on UV. On roofs and attics they shouldn’t be used due to their very low resistance to the column of water. Their use on roof should be limited to wind-insulation protection.

In practice this indicates use of these fibres as covering of timber walls of roof structure e.g. spire light (French - lucarne) and walls protecting them from excessive air flow from the outside that influences the thermal efficiency of attic. Sometimes wind-insulation is applied as mineral wool protection from wind (wool constituting roof thermal insulation). However in such cases the roof is usually boarded with initial covering. It should be mentioned that the majority of highly vapour-permeable roof membranes are at the same time perfect wind-insulation. For the complex structure of roof membranes and the demand of resistance to water column, typical wind-insulations (single-layer fibres) shouldn’t be used as an initial roofing.