An Opinion Piece by Howard Moutrie
What is it for?
I have often wondered the reasoning for the hinge side circulation space for a door opening towards you. The only reason for which I could think was so the door handle did not strike the wall preventing the door from fully opening. I sought the advice of other senior access consultants, some of whom are also long standing ME-64 committee members. That is, they are involved in writing the AS1428.1 and thus should have a good understanding of its requirements. They were of the same opinion. But to me, I cannot justify this dimension and, in this article, I will explore the validity of this circulation space.
So, let’s be clear: the space in AS 1428.1-2009 is indicated in Fig 31(h) and a similar situation in 31(f).
[Source: AS1428.1-2009, Figure 31 (h)]
The figure clearly shows 2 things: the door is only open 90 degrees and the measurement is taken to the inside of the door face. This is different to the diagram in the Livable Housing Guidelines (LHA), which shows the door open >90 degrees so that the door handle does not encroach into the clear opening. But the LHA diagram doesn’t specify a hinge side circulation space. It does indicate a hinge side dimension, but the terminology used – door thickness, handle and rebate – does not really relate to the distance indicated, which is the door thickness and door frame.
[Source: Livable Housing Design Guidelines]
So, if we assume that the reason for the hinge side circulation is to allow the door to open 90 degrees, what are the design parameters? As most of AS1428.1 is based around the requirements of a person in a wheelchair, it can be assumed that it was considered that the door handle, which must be located at a minimum height of 900mm, would not interfere with a wheelchair passing through the opening and thus there is no need to open more than 90 degrees. The minimum thickness of a door can be considered to be 35mm (often 40-50mm for external and glass doors), the minimum door frame thickness can be taken to be 38mm plus 2mm for the hinge, so the overall width of the door assembly would be a minimum of 75mm. See diagram. If the space required is 110mm, then the remaining section of wall from the door frame is 35mm. If the door frame was 50mm thick and the door 50mm thick (a typical glazed shopfront) then the remaining wall would only be 10mm.
If the reason for the hinge side space is to accommodate the door handle, AS1428.1 limits the projection off the door face of the handle to 45mm plus the thickness of the door lever/pull handle. If we say the door handle is 10mm, then the maximum space required is 55mm plus the door thickness (say 40mm), is total 95mm. Clearly, the determining factor is the thickness of the door frame and the projection of the door handle. If the door frame is wider than the projection of the handle, no further wall projection is required.
[Source: Howard Moutrie]
The reason for me raising this issue is twofold. Firstly, in NSW the certifiers have become increasingly pedantic and are checking this space is provided to the millimetre. I note that in some cases, they are requiring the 110mm from the wrong face of the door. The second reason is architects and designers are not sufficiently considering the wall construction. In a brick wall it can be possible to construct a nib of 30mm, but it is fiddly and requires the cutting of bricks. If the wall is constructed from concrete blocks, then the situation is basically impossible, and the block layer will either not have any space at all, or increase the space to a half block. The latter can have further implications by reducing the latch side circulation space – I have found this to be a common defect. I acknowledge that this could be overcome by the architect/designer better understanding how things are built, however, I really question if the space is required at all, or at least what is the actual space required.
To open the door, the activity will be at the latch side, and I can see no benefit in the hinge side space. The process of opening a door with a frontal approach, with the door opening towards you, would be:
- Position the wheelchair on the latch side so that you can reach the door handle to open the door.
- Reverse to allow the door to open.
- Travel to the door opening. This will be on a slight angle, towards the hinge side.
- Travel through the door opening, still on the angle but probably straightening as you proceed through the door, depending on your ultimate direction of travel.
This process would not require the door to fully open because at no stage would you be travelling perpendicular to the door plane. On this basis, the door hinge side circulation space has no impact on the usability of the door.
So where did this requirement originate? In NSW, many years ago there was Ordinance 70. It was an early forerunner of the BCA, and in “Specification No9 Access for Disabled People” there was a note which said that where a door opens against a wall or fixture sufficient space shall be provided to allow the door to open 90 degrees. This eventually translated to 110mm in AS1428.1. As discussed earlier in this article, the actual space required is dependent on the door thickness and the door handle, and 110mm would be considered the maximum required to allow a door to open the full 90 degrees, except for large pull handles used on main entry doors.
For comparison, I have researched other Standards. The ISO Standard basically replicates AS1428.1 (though with an increased latch side space). The US ADA Standard has no specific requirement, other than the door must be able to open 90 degrees. The UK Standard has no requirement, but the clear opening is measured clear of the door handle, so the door must open more than 90 degrees or the opening width is increased.
Also, reviewing older versions of AS1428.1, the dimension doesn’t change with respect to changing the clear door opening width, nor between the A80 and A90 wheelchairs. This would suggest that the space is not determined by the wheelchair.
I think the original assumption, that the dimension is to allow the door to open 90 degrees is correct, however, it would seem that 110mm may be excessive and that a lesser dimension could be easily justified. An interesting outcome of this requirement is that the greater the hinge side space, the further the door can open, if it is not fitted with a door closer. This means increased manoeuvring to then close the door.
This raises another issue, there has been insufficient consideration given to the use of a door closer. Depending on the type of closer used, a larger space may be required to stop the closer hitting the adjacent wall. If a backcheck is incorporated to minimise the impact of a door opening into an adjacent wall, this may in fact prevent the door from opening the full 90 degrees, particularly when being opened by a person using a wheelchair.
Based on the foregoing, I believe the required 110mm is a “one size fits all” solution and varying this dimension could be justified depending on the actual door set installation.