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Windows assembly guidance

This assembly guidance provides a qualitative result only if there are normal temperature and humidity conditions inside the building, i.e. temperature is not lower than + 16 °С and humidity is not higher than 60%.


Building physics covers heat and soundproofing. These are too sections that help to find specific solutions during building and repair works and in particular during installation of the windows.


Causes of heat loss and condensation should be sought in the construction of the wall and in the area of contiguity of window box and wall.

Sash pulley must meet certain requirements. Its construction should be:
  1. Airtight
  2. Heat-insulating
  3. Waterproof
  4. Resistant to temperature and UV effects from the outside
  5. Impermeable for water steam from the premises side
  6. Resistant to deformation, should have long service life.

The above mentioned basic requirements are provided at three levels:Levels.

Level I. The border between external environment and room

Level I correspond to a certain conditional surface which delimits outside climate and microclimate inside the room. The temperature of this surface should be above the due point temperature of the room otherwise there is a risk of condensation and damage of adjoining building construction (mold, fungus, corrosion), as well an increase of heat loss and the formation of cold bridges.


To avoid the temperature lowering to the due point temperature on the border between outside environment and the room is possible through the application of wall, floor and ceiling constructions with appropriate thermal conductivity. Heat transfer coefficient U (sometimes K) in System of Units expresses the amount of heat that will pass through 1 m2 of flat wall with thickness of 1m from a given material per hour at a temperature difference of 1° С. The unit of heat transfer coefficient U measurement – Watt/m2K and its value must always be stated in all project documentation.

Level II. Protection from weather

This level prevents the penetration of moisture into the window construction from outside. There has to be foreseen controlled derivation of rain water in the sash pulley. However moisture that gets into the functional area should also be able to go out.

Level III. Functional area

In this area first the heat and sound insulation has to be provided. For providing of these functions this area should „stay dry” and isolated from room’s microclimate. Taking into account that moisture contained in the warm air of the room at a temperature of about 10 °С falls down in the form of condensate it is necessary to ensure its safe derivation. And here we have the basic rule: „More hermetic outside than inside”. At the same time it has to be borne in mind that deformation of building constructions happens in the functional area, the temperature changes of the window construction size, the effects of gravity and load arising during use of the window. However sealing materials must be flexible and compatible with the materials of the building construction elements and also applied in accordance with manufacturer’s recommendations.


This guidance is primarily for installers whose task is the implementation of the correct installation of high-quality windows and filling of the side welds in accordance with rules, following all effective building rules and taking into account construction types of the walls.

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