Doorways, Corridors And Circulation Space
Door widths and corridor dimensions are the first thing a wheelchair user tests and the last thing that can be changed. Getting the circulation right is a planning exercise done before any finish is selected.
What door and corridor widths does an accessible dwelling need?
Clear opening widths at doorways rather than nominal door sizes, corridors wide enough for the turn into each room rather than just for straight travel, and a clear circulation space at every door approach sized for the turning circle of the equipment in use. The governing dimension is usually the turn, not the straight run, and it is checked room by room against the standard that applies to the dwelling.
Circulation is the least visible part of an accessible dwelling and the part that decides whether it works.
A resident does not experience a door width as a number. They experience whether they can get through the door without a three point turn, and whether they can do it alone.
Clear opening, not nominal width
The number that matters is the clear opening: the actual gap between the open door leaf and the frame on the other side.
A nominal door size does not give you that. The leaf thickness, the frame rebate, the hinge type and the door stop all take width out, and the difference between the nominal size and the clear opening is routinely enough to matter.
Which means the specification is written as a clear opening and verified on the shop drawing, not as a door size. In a factory build that verification happens before fabrication, which is where it belongs.
Where the clear opening is tight, an offset hinge recovers a useful amount by swinging the leaf clear of the frame. It is a small item that solves a dimension problem which would otherwise mean moving a wall.
The turn is the governing dimension
A corridor wide enough to travel along is frequently not wide enough to turn out of.
Getting into a room from a corridor is a ninety degree manoeuvre, and the space required depends on both dimensions at once: a wider door needs less corridor, a narrower door needs more. That relationship is set out in the standards and it is the calculation most often skipped.
Which is why the test is applied at every door in the dwelling rather than once. The entry, the bathroom, the bedroom, the laundry and any external door all have their own approach condition.
Circulation space at the approach
Beyond the turn, there has to be somewhere to be while operating the door.
Space on the latch side to reach the handle and pull the door open while clear of its swing. Space to close it behind you. On an outward opening door, space to back up as it comes toward you.
A door with adequate clear opening and no approach space is a door a wheelchair user cannot use without help, and it is the most common failure in dwellings that satisfy every width requirement on paper.
Turning space in rooms
Each room needs a space where a chair can turn to face back out.
In a bedroom that usually means a clear area at the foot of the bed, which has to survive the furniture. In a bathroom it is the governing constraint on the whole layout, which is the subject of [accessible bathroom design](/blog/accessible-bathroom-design-in-sda).
The practical risk is that the turning space exists on the drawing and disappears once the dwelling is furnished. Which means the furniture layout is part of the design rather than something the occupant resolves later.
Hardware, reach and operation
A lever handle rather than a knob, at a height within the reach range, on a door that can be operated with a closed fist.
Door closers are the quiet problem. A closer strong enough to latch the door reliably can be too strong for a resident to open, particularly on a fire door where the closing force is not optional. Resolving that is a selection and adjustment exercise rather than a choice between compliance and usability.
The switch and outlet positions around doors sit in the same family of dimensions, covered in [switches, outlets and reach ranges](/blog/switches-outlets-and-reach-ranges).
Thresholds and external doors
Every external door is a level transition and a weather junction at the same time.
A flush threshold that is also weathertight needs a drained sill detail and a graded external surface, designed together. That is straightforward in a factory build where the floor and the wall are made as one assembly, and it is one of the details that is routinely compromised when it is formed on site.
Why it cannot be fixed later
Walls carry services and sometimes structure, and a corridor cannot be widened without moving both.
Which makes circulation a design-stage decision with no later remedy, and the reason it is resolved during the early stages rather than at documentation. The sequence that forces it to happen is the one described in [the eight design stages](/blog/the-eight-design-stages-explained).
MADEmodular / MADEbetter.
MADEmodular / MADEbetter.