Standard door sizes allow for the mass production of doors ready-made for installation. This helps drive down the cost of a door, as having custom doors made is generally more expensive. In Australia the most common standard door width is 820mm, but there are other sizes that are popularly used. These are as follows:
- 2040x820x35mm (This is the most common size)
Doors that fall outside of the range listed above are considered to be non-standard, and will either require custom framing and hanging, or will need to be modified to fit the space.
There may be many reasons why custom doors need to be fitted; it could be for aesthetic purposes, for special needs and disability access, or simply because the space doesn’t allow for a standard door size - as is often the case when converting a window casement into a door frame.
Standard door handle height
Regardless of the size of the door, the Australian Standard AS 1428.1 (Design for access and mobility, Part 1: General requirements for access) recommends that the height of the handle should fall within 900mm and 1100mm above the floor. This is around waist height for the average adult. Generally speaking, only much older doors or those installed for a special purpose will deviate from this recommendation.
Standard door handle backset
The 'backset' of a handle is the measure of the distance between the door handle and the outside edge of the door (i.e. how far it's set back from the edge of the door). This is measured from the very edge of the door to the centre of the door lever or door knob - easily measured at the top part of the door handle assembly.
The most common backset measures for house doors in Australia are 60mm and 70mm.
Having said that though, you should never just assume that a door will fit a particular lock without checking the manufacturer's specifications for that particular hardware. There's no set-in-stone 'standard', and different door and lock manufacturers produce all kinds of different sizes, as well as different product ranges.
If you're looking at replacing a door handle or installing a new door, make sure the length of the latch matches the backset for the door.
Other things to consider
When measuring up a door frame, don’t forget to allow for clearance for the door to swing on all sides, not just the base. Also take into account whether or not you are installing a door with a sill (a horizontal member at the bottom of the door frame) - this will affect how much clearance you’ll need to allow for on the bottom.