Types of windows & their uses

 

A window may be defined as an opening made in a wall for the purpose of providing day light, vision and ventilation. The construction of window is identical to 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, panelled and glazed or panelled type. Windows are normally provided two leaves. The selection of size, shape, location and the number of windows to be provided in a room depends upon the following considerations.

·      Size of room to be lighted.

·      Location of the room and its utility.

·      Architectural treatment is to be given to the building.

·      Direction of wind and its speed.

·      Climatic considerations of the site such as humidity, temperature variation etc.

Based on the above, following thumb rules have been framed to determine the area requirements for windows in a room. The size and hence the number of windows can thus be worked out, once total area required for window opening is known.

1.Total area of window opening should normally vary from 10 to 20% of the floor area of the room. In hot and arid regions, it could be 10 to 15% of the floor area. When the building is to be located in hot and humid regions, the area of window openings should vary between 15 to 20% of the floor area.

2. In case of public buildings like schools, offices, factories, hospitals etc. the minimum area of windows should be 20% of the floor area.

3. For adequate natural light, the total area of glass panes in windows should be at least 8% of the floor area.

DESIGN OF WINDOWS

The points to be kept in view while making provision for windows in a room are:

·      The size and number of windows should be sufficient to provide adequate light and ventilation in the room.

·      Windows should be located opposite to each other where ever possible.

·      The window sill should be placed at 75 to 100 cm. above the floor level. This is considered reasonable height for the inmates to have a convenient look outside. In case of bath and W.C., and the other situations where privacy is desired, window sill should be kept at 1.75 m above the floor level. The top of windows and doors should however be at the same height.

·      Buildings in humid region need special attention for adequate ventilation of the room. The area of window opening in humid region should be maximum and the window should be so located as to permit maximum ventilation of the apartment.

·      The shutter of windows in external walls should open outside. This checks entry of rain water inside the room.

·      All external windows, especially the ones on ground floor, should be provided with mild steel round or square bars or steel grills to safe guard against theft.

·      Windows in external wall should be provided with chajja projections to prevent the entry of the rainwater in the room. Similarly, it is desirable to slope the window sill towards the external face of wall. The sill should preferably be weathered and throated to throw the rain water off the face of wall.

CLASSIFICATION OF WINDOWS

1.Fixed Window:

In this type of window, the glass pane or glazed shutter is permanently fixed in the opening in the wall. This type of window is used in situations where light or vision alone is needed as no ventilation is possible through fixed windows.

2.Pivoted Window:

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 weighs connected by cord or chain passing over pulleys is provided for each shutter. By this arrangement the window can be opened at top or bottom to desired extent by pulling the metal weighs suitably.

4. Sliding Window:

In this type of window, the shutters move on 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 transom 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 divided the total panel space of window shutter into panels of small size. The sash bars have rebates in fixing glass panels. The glass panels are cut 15 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 Ventilated 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 is 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 angle of inclination of the louvers or blades to the vertical stiles should be angle 45. This type of window provides ventilation and light even when the opening is closed. Such windows are commonly recommended for bathroom, workshops, and other areas where privacy is the main consideration. It is however, difficult to maintain them clean as the dusts 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 pf metal windows is getting increasingly popular these days. Windows made of metals, like mild steel, galvanised mild steel, aluminium, bronze, 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 possess 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 of 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.

Mild steel being cheapest of the above metals, steel windows work out to be most economical. Hence, steel windows are extensively used in all types of buildings. The window of required design can be fabricated out of standard light rolled steel sections.

Steel windows can be fixed direct in the masonry opening in the wall or it may be fitted in a wooden frame fixed in the window opening in the wall. In fixing metal windows, it has to be ensured that no structural loads, stresses or movements in the structure and transmitted to the window. This is necessary to prevent damage of the window as the thin rolled steel section forming the window unit cannot bear such loads or strains. This can be achieved by respecting the following requirements.

·      The size of window opening is kept slightly more than the size of the window unit so as to allow some clearance between frame and the sides of opening.

·      The window is fixed into prepared opening i.e. only after the items of masonry work for the opening as well as the lintel etc. are complete and fully set.

Method of fixing steel windows:

1.The prepared opening is cleared of all obstructions and the exact position of the window from the external face of wall is marked on the jambs with the help of chalk lines. The marking of chalk line is also made along the head and the sill of the opening.

2. The frame of the steel window has holes at locations where hold fasts or lugs are to be provided. The holes are known as fixing holes. The position of the fixing holes is measured from the window unit and marked on the chalk line at corresponding points.

3. In case of brick masonry, the steel window is invariably fixed to the opening with the help of small sized hold fasts also known as lugs. For installing the lugs, holes are cut in the brick work, normal size of the hold being 5 cm. square and 5 to 10 cm. deep.

4. In case of reinforced concrete work or stone masonry it is difficult to cut holes for fixing the lugs in a prepared opening. In such situation, wooden blocks are embedded in appropriate places in the concrete or masonry during casting or construction of the wall. It is however, important that the plugs or set very accurately so as to match the alignment of the fixing holes in the window frame. The window unit is subsequently fixed to the plugs with the help of galvanised iron wood screws.

5. When the steel window is to be fitted into wooden frame already fixed in the window opening, the wooden frame is invariably rebated to receive the steel window unit. After the window unit is set is position accurately, it is secured to the wooden frame by means of G.I. wood screws.

Advantages of Steel Windows:

1.Steel windows are stronger and more durable as compared with wooden windows.

2. Weather does not have adverse effect on steel windows and unlike wooden windows they are not subjected to expansion or contraction of joints.

3. They are rot proof and remain free from hazards of termites, fungus and white ants.

4. They are highly fire resistant.

5. They are fabricated with greater precision and quality control. Hence steel windows present elegant appearance and steam lined fishing which make them superior to wooden windows.

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 of light and ventilation.

10. Corner Window:

As the name suggests 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 feature for improving the elevation of the building.

11. Dormer Window:

It is a vertical window built in the sloping side of a pitched roof. This window is provided to achieve proper ventilation and lighting of the enclosed space below the roof. Dormer window also serves as an architectural feature of the building.

12. Gable Window:

The window provided in the gable end of a pitched roof is known as gable window.

13.  Sky light:

This is a 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 after 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 up for accommodating the sky light is properly treated by lead flashing so as to ensure complete water proofing of the roof surrounding the opening.

14. 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 transom. The shutter of the fan light may be provided at the centre or it may be top hung.

15. Ventilator:

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 rail and the other to the bottom rail.

FIXTURES AND FASTENINGS FOR DOORS AND WINDOWS

The fixtures and fasting for doors and windows can be of iron, brass or aluminum. It is however important to ensure that the item should be reasonably smooth and free from sharp edges and corners. The screw holes in the item should be of counter sunk type. Iron fixtures and fastening are normally black enamelled or copper oxidised. Brass fittings on the other hand are oxidised or finished bright chromium plated. Aluminium fittings are normally anodised. The fittings and fastenings can be broadly grouped under:

Hinges:

Different types of hinges commonly used for doors and windows are described below.

1.Butt Hinges:

This type of hinge is most commonly used for fixing door or window shutter to the frame. The sizes of hinges vary from 50mm. long x 37 mm. wide to 125 mm. long x 75 mm. wide. One flange of hinge is screwed on to the edge of the shutter and the other flange is screwed to the rebate in the frame. For normal size of door or window three hinges are used for each shutter.

2. Back flap hinges:

This type of hinges are used with thin shutters where butt hinges cannot be used. These hinges are fixed to the back side of the shutters and frame and hence they are called back flap hinges.

3. Counter flap hinges:

This type of hinge has three parts and two centres. Provision of this type of hinge enable the shutters to be folded back to back.

4. Strap hinges:

This type of hinge is normally used with ledged and braced doors, garage doors, boundary wall gets etc. The hinges have long arms which are fixed to the shutter and the rebate in the frame.

5. Garnet hinges:

This type of hinge is also known as T-hinge, and is commonly used for battened or ledged and braced doors. The long arm of the hinge is screwed to the shutter whereas the short arm or plate of the hinge is screwed to the door frame.

Bolts:

1.Tower Bolts:

In this type, the bolt passes through two or three stapples attached to the base plate. The plate is screwed to inside face of the door shutter and the bolt engages in a metal socket screwed to the frame.

2.Barrel Bolts:

This type of bolt is similar to tower bolt except that the stapples are replaced by a barrel.

3. Hasp and Stapple bolt:

In this case the hasp is secured to the shutter whereas the stapple is screwed to the door frame.

Eye and Hook:

This type of fitting is used for keeping window shutter in position when the window is open. The hook is fixed to the sill of the window frame and the eye is fixed to the bottom rail of window shutter.

Handles:

Handles are manufactured in a variety of designs.