The Australian Dream Series


Window sizes & locations

The size, or more relevantly, the shape of the windows you choose will be influenced by the style of home you are looking to build. A period style home will employ windows suited to the era. A beachside home may incorporate large glass areas to capture the ocean views. Although the primary function of windows is to admit daylight and ventilation, the size, colour and design of your windows will have a lasting influence on the presentation of the house.

To give some background information on window sizes. - The minimum amount of light and ventilation permitted for each room is regulated under the building code. The area of light provided must be at minimum equal to 10% of the floor area of the room. Ventilation must be provided by permanent openings or windows or doors which can be opened equal to at least the equivalent of 5% of the floor area. From this it can be seen that for a 3 meter by 3 meter room, the minimum glass size required would be 1000mm by 900mm, well below what would normally be allowed for in a window selection.
Added to this light can be 'borrowed' from another room. That is, a room with glass panels abutting another room which has a light area greater than 10% of the combined floor areas, will meet the requirements of the regulations.

In most homes the top of the window (window head) is set at 2100mm above the floor level. This then lines up with the top of external door openings creating a uniform look from both inside and outside. Period style homes with higher ceilings and possibly feature glass infills above doorways will more than likely be suited to windows being set at 2400mm. (or in line with infill panels)
For example, in a 'normal' home a 1500mm high window would be 600mm above the floor; a 1200mm window 900mm above.
Unless you are sure of the visual outcome I would recommend not moving away from this industry norm. There are exceptions and some designs may be enhanced by staggered window heights - but it does have to be done exactly right and it does have to suit the style of home.

The overall comfort and control of heating and cooling costs of the home will largely be affected by the size and location of the windows. In broad terms northern facing windows should be maximised to take advantage of winter sun; southern windows should be minimised to reduce heat loss and cooling by cold winds; eastern windows will be better being taller and narrow and westerly facing glass if required, shallow and up towards the eaves to provide shading protection.
Obviously this is not always practical and adding items such as external shading, heavy drapes or even double glazed windows may need to be incorporated.
Glass selection for various situations and applications is now made easier with the introduction of a window energy rating system (WERS) taken on by most window manufacturers.

Due to the many variables dictating the sizes of windows - the style of home, orientation etc - it isn't possible to nominate the best sized window to be used for a particular area but the following may assist in your decisions.

Try to keep window panel sizes uniform - an 1800mm wide window (made up of 2 equal panels) will tie in with a 900 wide (single panel) or a 2700 wide (3 panel) window. A 1200mm wide (single panel) window will look uniform with a 2400 (2 panel) window. A 900 and a 1200 window side by side will look unbalanced.

A kitchen window height of 1 meter will leave around 200mm of splashback above the bench top. A 1200mm high window will place the window sill directly on the bench top. (kitchen bench heights are 900mm)

A bathroom or ensuite window 100mm taller than the sizes above will result in the same splashback heights as vanity tops are set at 800mm.

In a standard 900mm wide toilet, windows are normally 600mm wide to allow room for full width architraves to the side of the window. The next size up - 850mm - can be used but the architraves will need to be trimmed to fit between the window reveal and the side walls. With ornate mouldings this can take away from the effect.
Window heights of up to 1200mm are often used with the most common possibly being 1000mm.

Windows in master bedrooms, being in many cases at the front of the home, are generally 2100mm high . Windows to second and third bedrooms often 1200mm high allowing 900mm below for the bed or a desk to be positioned.

Window sizes are generally the same with all manufacturers in that they are manufactured to fit in with brick size openings. Moving away from these standard sizes will require the supply of a 'special' sized window, costing more. Window size brochures are available from all manufacturers.

Wndows are coded as to their size and type (the format often seen on house plans or window schedules) The code is comprised of a series of letters and numbers.
For example AS1812 denotes an Aluminium Sliding window 1800mm high by 1200mm wide. TDH1218 denotes a Timber Double Hung window 1200mm high by 1800mm wide. Other prefixes are AW - awning, TAW - timber awning, CW - casement, ADH or ADW - aluminium double hung.
In the number section of the codes, the first two numbers refer to height and the second two to width.



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