Windows and doors can be installed once the wall, necessary openings and lintels have been completed. In this film, we will focus on windows.
The main features of windows are transparency, adequate light transmission, and the possibility of regular ventilation. All of this must be achieved while meeting the highest possible thermal insulation and air tightness requirements. Additionally, window structures can have other functions, such as providing shade or restricting visibility at certain times.
There are a wide variety of ways that windows can be designed to open. Traditionally, the most common designs are fixed or side hung windows. There are also double or multi-pane casement windows, and even sliding sash windows. In modern practice, windows have developed beyond these designs to include other special opening methods such as bottom hung, top hung, tilt-and-turn, and pivot windows. Windows can have any combination of elements, with different functions, opening methods, and shapes. Designs which are conceivable can be realised practically by sequencing or integrating the elements.
1. Traditional windows
For centuries, wood was typically and almost exclusively used to make windows. Traditional wooden windows were constructed with simple timber frames. Typically, single-sash, double-sash, or multi-sash casement windows with intermediate mullions were glazed using putty and glazing beads. Simple flat glass was used for the pane. Alternatively, metal windows were also used but these were not ideal in many respects.
The flat jamb design was typically installed within a a recessed wall opening, with planking surrounding the reveal surface. Sashes could be mounted on either side of the flat jamb: one opening outward and one opening inward. In both configurations, double stop occurred between the frame and sash. The outer wings opening outwards could also function as shutters, providing shade especially during the summer.
The block frame also known as the rabbated jamb design has the frame positioned behind the stepped bricks of the reveal. The frame is designed with two different profiles: on the sides and at the top, there is a cross-section that allows a double stop; at the bottom, there is a single stop with an outward slope. The inward-opening sash also has two different profiles: uniform on the sides and top; while the bottom part of the sash is joined by a deflector, covering the bottom frame. The bottom frame is also connected to the drip edged tinwork of the sill to protect the horizontal surface of the wall opening from water.
The single block frame (~ rabbated jamb design) was only used for lower performance requirements The most frequently used design is duplicated block frames (~ duplicated rabbated jamb design). As with the single block frame, this is typically installed in a recess by simply doubling the single solution. For a double casement formation, a middle mullion piece was used both on the outer and the inner sides.
The unified block frame profile (~ unified rabbated jamb design) can be considered the predecessor of modern timber windows. Frames were unified by glueing them together while the sashes were bolted. A double-glazed sash was formed with three stops between all frame and sash profiles.
2. Modern windows
Modern doors and windows have perfected air and vapour tightness, thermal insulation, and glazing safety. Materials for frames and sashes are quite varied: apart from modern wood cross-sections, metal profiles have undergone a major transformation, and plastic and composite doors and windows are now commonly used.
Modern wooden windows differ from the traditional casement windows of unified rabbeted jambs mainly in the width of their profiles. Profile widths can range from 78 to 106 mm. Wider cross-sections are necessary due to heavy double or triple-layer thermal insulation glazing. The space between the glass layers is filled with noble gas to achieve better thermal insulation. There are at least three stops between the frame and the sash, where the internal seal is improved by a rubber gasket. To improve thermal insulation in cases of high demand, the profiles, which are usually made of pine, are fitted with thermal insulation, such as cork inserts. There is a metal water deflector profile at the bottom of the case.
The profiles of plastic window frames and sashes consist of 5 to 8 closed air chambers with steel reinforcement in their core. There are at least 3 stops between the frame and the sash - usually fitted with a rubber seal. By using the 3-layer thermal insulation glazing system found in wooden windows, the width of the profiles can be 70-100 mm. The base colour of the profiles, typically made of PVC, is white. However, they can be made to look like wood on the inside and outside with a foil coating.
Among metal windows, steel profile windows are more prevalent in buildings with lower performance standards, where thermal insulation requirements are minimal or absent. In this case, corrosion protection is also a particularly important consideration.
Aluminum window frames are constructed from hollow profiles, similar to those used in plastic windows. However, aluminum has poor thermal insulation properties so thermal break inserts are installed around the profiles. There are at least 3 stops between the frame and sash, which are almost always fitted with rubber seals. Thermal insulation glazing is similar to that used in wooden and plastic windows (typically 2 or 3 layers of glass and special rubber seals). The great advantage of aluminium windows is that they are more durable and resistant than most others and require minimal maintenance.
3. Shading appliances
Shading structures can be important accessories for doors and windows. Very often, they are installed at the same time as windows or doors. Traditionally, external shading devices have a long history. These include shutters, which consist of solid boards or completely-closed frame inserts. Louvres are a more complex solution with rotating slats enclosed in a separate sash. These slats allow the amount of light entering the room (and the transparency) to be adjusted. Shutters and louvres can be opened using either a sliding system or a hinge. Both versions are available in a multi-sash solution which can be stacked like an accordion.
Roller blinds are modern types of external shading appliances. To install them, a roller blind box must be mounted on the upper part of the window. The slats covering the entire surface of the roller blind can be rolled down from inside the roller blind box and rolled back up again. The slats and the box are usually made of plastic or aluminium. The box can be external or concealed, depending on its location. Concealed boxes can be installed under, in front of, or integrated into the lintel.
Roller blinds, also known as Venetian blinds are plastic or aluminium shading devices which are integrated into windows and/or doors. These are often installed between two layers of glass and operated in a similar way to shutter slats. They can be rotated, and pulled up and down. Modern Venetian blindes are also often used in aluminium-wood or aluminium-plastic windows in the space between the outer glass and the inner thermal insulation glazing.
Also, there are fixed shading devices that are an integral part of the facade which are installed in the final phase of construction, well after the windows and doors have been installed. These are typically well-coordinated with the windows and doors, but their shading effect is extends to the area in front of the windows and doors.
