PVC lift-and-slide door Kömmerling HST 76

A significant increase in the window's stability is achieved by installing steel reinforcements all the way around the outer frame and the sash (right into the mitred corners). Only this detail allows the corner bearing and the restrictor stay to be screwed into the steel core with all four screws. This continuous screw fixing is required to provide a load-bearing capacity of over 100 kg. The dimensional stability of the profile construction makes it possible to produce large elements.

The term Zarge (outer frame) denotes the fixed part of the frame that is built into a window opening and within which the movable part of a window pivots on hinges. In everyday speech it is also called the Fensterstock, or window frame (Fensterrahmen) as opposed to the window sash. In window construction, by contrast, both the outer frame and the window sash belong to the window frame. The same nomenclature applies to doors, where one speaks of a door or window casing (Zarge).

The term spacer refers to the window components that form the transition between the glass surface and the frame profile. They are also responsible for the distance between the individual glass panes of a multiple glazing unit, hence the name. In order to achieve a good U-value and to significantly minimise heat losses at the edge seal, modern spacers are no longer made of aluminium, but of flexible structural foam, composite plastic or plastic-coated stainless steel. These are used when a window is to be produced with what is known as a "warm edge". Passive house standard windows are only possible with such modern spacers.

The term chamber system refers to the type of construction used in uPVC windows, in which several air chambers sealed off from one another within the frame profile are intended to provide optimal thermal insulation. The insulation values of uPVC windows with more air chambers are usually better. Only the Uf-value, which indicates the thermal transmittance coefficient of the frame, allows a precise statement to be made about this. The first uPVC windows were fitted with only a single chamber and therefore did not offer good insulation. Modern windows have multi-chamber profiles and extend up to the 7-chamber system, often referred to as insulating chambers.

Windows with an add-on shell

The add-on shell, made from a high-quality aluminium alloy, is clipped onto the outside of the windows and wraps around the sash and outer frame. It gives the window element a durable, weather-resistant surface, a wide choice of colours and easy maintenance. Beneath the shell lies a different core in each case: uPVC or timber.

Wall design with an add-on shell

An add-on shell is a wall cladding that is placed in front of a load-bearing masonry structure and connected to it. This may be done for aesthetic or insulation-related reasons. Common examples of add-on shells are brick facings or timber, sheet-metal or plastic cladding on external walls. Insulation materials applied to the outside, which are then rendered or otherwise clad, also count as an add-on shell.

On internal walls, plasterboard or timber-panel cladding, composite panels or coarse chipboard are used, for example.

Modern windows and doors are constructed to keep the greater part of street noise outside. The sound insulation values (the sound reduction index) indicate how effectively the sound damping of a building component works.

The standard DIN 4109 "Sound insulation in building construction" sets out the requirements for sound insulation and defines the sound insulation classes. The sound insulation value is given in decibels (dB).

Example: the sound insulation value, or sound reduction index, of a window with insulating glazing is 32 dB Rw,P (or Rw p). The designation Rw denotes the reference value and P stands for the test value (tested in the laboratory). The sound reduction index of 32 dB Rw,P indicates that, in the laboratory measurements, the tested building component reduced the noise level by 32 dB.

In construction, the rule applies that the test value of a building component (Rw,P) should be 5 dB higher than the actual value (Rw). On average, a modern window with standard insulating glazing lets through only about 10% of the noise.

Sound insulation classes and the associated sound reduction index:

• Class 1 25-29 dB
• Class 2 30-34 dB
• Class 3 35-39 dB
• Class 4 40-44 dB
• Class 5 45-49 dB
• Class 6 over 50 dB

For living and working spaces, sound insulation class 1 is the standard; for schools, classes 2 and 3; for hospitals, 3 and 4.

Watertightness against driving rain describes the resistance of a building element (e.g. a window, glass wall or door) to driving rain, i.e. rainfall whose vertical direction of fall is altered by the wind. It is evident that the dynamic pressure exerted by driving rain is determined not only by the intensity of the rain itself, but also by the strength of the wind.

When windows and doors are tested for their watertightness against driving rain, the building elements are sprayed under a pressure of 0 to 600 Pa for between 15 and 55 minutes. The classification is made using numbers and letters, whereby the number from 1 to 9 corresponds to the test pressure and the letter (A or B) to the respective test method. A - unprotected windows and doors (e.g. not protected by a canopy), B - a partially protected type of construction.

Windows, glass walls and doors should also be able to withstand strong wind. The higher up in a building the corresponding component is installed, the greater the wind load. The wind load to which a building or its components are exposed also depends on the location of the building itself.

Wind load resistance is classified in accordance with the DIN EN 12210 standard: from Class 0 (not tested) to Class 5 (high resistance). In addition, three classes (A, B, C) are distinguished according to the relative frontal deflection under wind load. The final classification of components with regard to their wind load resistance is expressed using a letter-number combination, where the letter indicates the class of relative frontal deflection and the number indicates the wind load class.

Air permeability refers to the air exchange between the room and the outside. Windows and doors are never absolutely airtight. For optimal air quality in the rooms this is also not desirable. Excessive air exchange likewise reduces quality of life and, moreover, causes high heating costs.

Air permeability (formerly referred to as the a-value) is currently expressed by the Q-value and classified according to the standard DIN EN 12207. In the case of complete components (e.g. windows or doors), an area-related value can be given - the ratio of the air volume in m3 to the area per hour (m3/m2 times h). For the joints, a length-related value can be given - the ratio of the air volume to the length of the joint per hour (m3/m times h). The reference point is an air pressure of 100 Pa.

Patterned glass is used wherever light should be allowed in but a clear view through is not wanted, for example in bathrooms, doors, cellar windows or as a privacy screen within offices. Shower cubicles are also suitable for the installation of textured glass panes, as the light transmittance of the glass makes them appear visually larger without allowing details to be seen. A popular way of separating a space without any loss of light is a partition made from a patterned glass wall – for example between the living and dining areas. Glass of this kind can certainly be regarded as an original decorative feature – for example as shelving, table tops and so on.

By choosing patterned glass you need not forgo any of the other outstanding qualities of our windows, as patterned glass can be combined with insulating glass and even safety glass. When combined with thermal insulation glass (insulating glass), the rough side faces the cavity between the panes, so that the surface of the finished product is smooth on both sides and easy to clean.

At FENSTERNORM you can choose from a wide range of patterned glass .

A RAL colour refers to standardised colours from a colour collection that has been authoritative for colour selection for over 85 years and is distributed by RAL GmbH under the name RAL Classic.

Each colour in the colour catalogue is assigned a four-digit colour number. The first digit is systematic: 1 - yellow, 2 - orange, 3 - red, 4 - violet, 5 - blue, 6 - green, 7 - grey, 8 - brown, 9 - white/black shades, and the remaining three digits are chosen sequentially.

For a surcharge, almost all products, such as timber windows, timber-aluminium windows, aluminium windows, roller shutters and external window sills, can be produced in a RAL colour of your choice.

Originally, only small panes of glass could be manufactured, and glazing bars served as dividers. Nowadays, glazing bars are used predominantly for aesthetic reasons.

A distinction is made between three different types:

Genuine or glass-dividing bars

This refers to a type of bar that divides the glass, so that each bar field is fitted with an individual pane. Windows made up of several small panes are rarely found these days. This method of construction closely resembles the original way of manufacturing and is therefore also very labour-intensive. In addition, heat loss is greatest with the glass-dividing bar variant. Every interruption of the pane is in direct contact with the outside of the window, and this creates a cold bridge.

Imitation or bonded-on bars

The so-called “Viennese bar” (Wiener Sprosse) is counted among the imitation glazing bars and represents the affordable alternative to genuine glazing-bar windows. This type of bar is visually indistinguishable from glass-dividing bars and is ideal for recreating slim bars. The surface-mounted bars are simply bonded onto the glass and merely sealed with silicone. For this reason, they have no effect on the insulating properties of the glazing.

This type of bar looks particularly attractive on country-style houses or restored buildings that are listed as protected monuments. They give the entire building an exceptional and historic appearance.

Internal bars

Internal bars are inserted as a bar grid inside the glazing. This eliminates the labour-intensive upkeep of the bar construction. A particular feature of bars located within the cavity between the panes is that, with triple glazing, the bar is placed in only one of the two cavities between the panes.

Today, glazing-bar windows are used predominantly in the renovation of listed buildings and, in new builds, serve more as a design feature. In doing so, they lend the window and the entire building a distinctive character.

At Fensternorm, you can choose as standard between internal bars in a width of 18 mm or 8 mm and surface-mounted bars in a width of 26 mm. Of course, we will endeavour to fulfil (almost) any other size requirement you may have.

The continuously growing demand for coloured windows and the increasing range of decorative variants opens up diverse possibilities for architects and property owners. The surfaces of uPVC windows are coated with so-called decorative foils and can be foiled on one or both sides. The frames can also be finished differently on the inside and outside. This allows you to create appealing decorative accents with windows and doors, both in the interior and on the façade.

Depending on personal taste, the window frames can be clad with a foil that reflects, for example, the natural look of wood. With their deceptively realistic appearance and their similarity to genuine timber windows, they offer the advantage of not requiring the high maintenance effort of being sanded down or repainted.

The window frame foil is extremely hard-wearing, robust, UV-resistant and weatherproof. It does not fade over time, and the frame does not change its appearance throughout the entire lifespan of the window.

The choice of window colours naturally depends partly on the appearance of the house and partly on the building regulations in force in some localities. Statutory requirements also apply to buildings that are already listed as heritage-protected. When modernising older buildings, the façades often may not be altered visually, but our window frame foils offer plenty of colour variants to choose from.