A window is defined as an opening made in wall for the purpose of providing day light, vision and ventilation. The construction of window is identical so that of door. Window consists of a window frame and shutter. The frame consists of two vertical members called jambs, one flat member connecting the jambs at top, known as head and another flat member connecting the jambs at their feet, known as sill. The shutter can be fully glazed and paneled type.
Types of Windows Used in Building Construction
Depending upon type of material used, nature of operational movement of the shutters, location and the manner in which they are fixed. Windows can be broadly classified as under:-
1. Fixed Windows
In this type of window the glass pane or the glazed shutter is permanently fixed in the opening of the wall. This type of window is used in situation where light or vision alone is needed as on ventilation is possible through fixed windows.
2. Pivoted Windows
In this type of window the shutter is capable of rotating about a pivot fixed to window frame. The window frame has no rebate. The shutter can rotate horizontally or vertically depending upon the position of pivot.
3. Double Hung Window
This type of window consists of a pair of shutters arranged one above the other which can slide vertically within the grooves provided in the frame. A pair of metal weights connected by cord or chain passing over pulleys in provided for each shutter. By this arrangement the window can be opened at top or bottom to desired extent by pulling the metal weights suitably. Thus in this type of window it is possible to have controlled ventilation. In addition the shutter can also be cleaned easily.
4. Sliding Window
In this type of window the shutter move an roller bearing and can slide either horizontally or vertically.
5. Casement Window
Windows where shutters open like doors are called casement windows. Similar to doors, this type of window has frame and shutter composed of stiles, top rails, bottom rails, vertical and horizontal sash bars with glass panes. Depending upon the design, the frame of a casement window can also have additional vertical and horizontal members known as mullion and transome respectively.
6. Sash or Glazed Window
In this case the window shutter consists of two vertical stiles, top rail and a bottom rail. The panel space between the stiles and the rails is suitably divided by small timber members or bars placed both horizontally and vertically or only horizontally to suit the design requirements. These bars are known as sash bars or glazing bars. Thus the sash bars divide the total panel space of window shutter into panels or small size. The sash bars have rebates or fixing glass panels. The glass panels are cut 1.5 to 3 mm., smaller in size than the size of the panel to permit slight movement of the sash bars due to temperature variation without damaging the glass panes. The glass panes are secured in position either by putty or by small fillets known as glazing beads.
7. Louvered or Venetianed window
In this type of window the stiles of shutter are grooved to receive a series of louvers which may be of glass or wood. The louvers are set within the grooves in inclined position so that they slope downward to the outside in order to run off the rain water and obstruct the horizontal vision at the same time. For economical construction the angles of inclination of the louvers or blades to the vertical stiles should be 45°. This type of window provides ventilation and light even when the opening is closed. Such windows are commonly recommended for bathroom, Wc,s (Water closet), workshops and other areas where privacy is the main consideration. It is however, difficult to maintain them clean as the dust gets easily deposited on the louvers. Sometimes the louvers or the blades are provided to the frame at both ends and in addition every blade is connected by a small hinge to a vertical batten. When the batten is pulled up, the gaps between the blades are opened and when the batten is pulled down, the gaps between the blades get closed.
8. Metal Window
Use of metal window is getting increasingly popular these days. Windows made of metals, like mild steel, galvanised mild steel, aluminium, bronze, stainless steel etc., are recommended especially for public buildings like offices, hospitals, schools etc. Bronze, aluminium and stainless steel are considered to be the best as they posses high degree of elegance, finishing, durability and are rust proof as well. However Bronze and stainless steel being very costly, use of windows made out these metals, is restricted to posh buildings where cost is not the prime consideration. As compared with bronze or stainless steel, aluminium windows are less expensive and hence they are commonly recommended for buildings where high degree of elegance is required at lesser cost. Aluminium windows are also rest proof, durable and require no maintenance and painting.
9. Bay Window
A window projecting outward from the walls of a room is termed as a bay window. Bay window may be square, rectangular or polygon in plan and it is introduced with a view to provide an increased area of opening for admittance of light and ventilation.
10. Clerestory Window
This type of window is used to achieve better ventilation and cooling effect in the living or main rooms of a building which have ceiling height greater than the surrounding rooms. Clerestory windows are provided near the top of the roof of the main rooms and they open out above a lean-to-roof or the roof slab of the adjoining verandah. Besides improving the elevation of the building, such windows also provide adequate natural light in the room. The window shutter is horizontally pivoted and the window can be opened or closed by use of two cords, one attached to the top rail and the other to the bottom rail of the shutter.
It is however, important to see that the upper part of the shutter opens towards inside of the room and the lower part opens outside. This is necessary to prevent rain water entering the room.
11. Corner Window
This type of window is essentially located in the corner of a room. By use of this window it is possible to ensure light and ventilation from two directions at right angles. In addition it serves as an architectural features for improving the elevation of the building.
12. Dormer Window
It is vertical window built in the sloping side of a pitched roof. The window is provided to achieve proper ventilation and lighting of the enclosed space below the roof. Dormer window also serves as an architectural features of the building.
13. Gable Window
The window provided in the gable end of a pitched roof is known as gable window.
14. Sky Light
This type of fixed window provided on the sloping surface of a pitched roof, the window being parallel to the sloping surface. The sky light is provided with a view to permit the room below to be fully lighted with natural light. The opening for the sky light is made by cutting the common rafter suitably. The frame work of sky light supporting the glass panels consists of an arrangement of trimming pieces, curb frame, bottom rail and top rail. The opening made for accommodating the sky light is properly treated by lead flashing so as to ensure complete water proofing of the roof surrounding the opening.
15. Fan Light
The function of fan light is to ensure cross ventilation in the room even when the door is closed. It also assists in providing natural light in the corridors or passages. Fan light is fitted between the head of the door frame and the transome. The shutter of the fan light may be pivoted at the center or it may be top hung.
A ventilator may be defined as a narrow window of small height provided near the roof of a room for providing ventilation in the room. The construction of ventilator is similar to that of fan light. The shutter of the ventilator is horizontally pivoted and can be opened or closed by use of two chords, one attached to its top and the other to the bottom.