The door is not the opening

Two measurement errors that both point the same way, so they compound instead of cancelling.

The measurement that catches people

A door described as 760mm is the width of the leaf. The clear opening — the gap something actually passes through — is narrower, because the door stop projects into it and the open leaf itself sits in the way. On standard hinges that costs typically 50 to 75mm, so a 760mm door is often a 695mm opening.

Meanwhile a wheelchair measured at 700mm across the wheels needs more than 700mm to pass through anything, because the user's hands sit outside the wheels on the handrims. Allow 50mm and the real requirement is 750mm.

So the door is 60mm wider than the chair and the chair does not fit, by 55mm. Both errors point the same way, which is why they compound rather than cancelling out, and it is discovered after the equipment has arrived.

The cheap fix nobody mentions

Before anyone quotes for widening a doorway: swing-clear hinges.

An ordinary hinge leaves the open door sitting inside the opening. A swing-clear hinge moves the leaf entirely out of the way when the door is fully open, recovering almost all of the hardware loss — often 50 to 65mm.

They fit an existing frame, take a few minutes to change, and cost very little. In the example above they turn a 695mm opening into something close to 760mm, which fits the chair with room to spare. It is frequently the difference between a building job and an afternoon with a screwdriver.

Measure the clear opening with the door fully open before assuming anything structural is needed.

A single step is a lot of ramp

At 1 in 12, every 100mm of height needs 1.2 metres of run.

One ordinary step is about 200mm, which needs 2.4 metres — longer than most front paths are deep. Three steps up to a front door is around 600mm, which needs 7.2 metres, plus a flat landing part way, plus flat space top and bottom to get on and off.

This is why so many ramp conversations end before they start, and why finding out early is worth the five minutes. The alternative — a platform lift, a different entrance, a threshold ramp for a single small step — is a much better conversation to be having in week one than in week six.

The gradient itself is a judgement rather than a rule. 1 in 12 is commonly cited for short ramps where someone is assisting; unassisted use generally wants shallower, and a powered chair has different needs again.

Turning is decided by the smallest dimension

Turning through 180 degrees needs the circle to fit in both directions, so a long narrow room does not help at all. The limiting figure is always the shorter of the two, and a 1000mm by 3000mm bathroom is a 1000mm bathroom as far as turning is concerned.

Where a full circle will not fit, a three-point turn often will, and it needs considerably less space. That is frequently the difference between a room that works and one that has to be reversed out of — which is manageable in a hallway and much less so in a bathroom at night.

Measure the whole route

The commonest survey mistake is measuring the destination and not the journey. A bathroom that works perfectly is no use if the hallway leading to it has a 90-degree turn that cannot be made.

Walk the route in order and measure every constriction on it: the entrance, each doorway, the narrowest point of every corridor, every threshold, every turn, and the approach to each thing that has to be transferred onto. A route is only as wide as its narrowest point, and the narrowest point is rarely the one anyone expected.

What a measurement is not

Comparing a number against a figure is not a compliance check. Building codes and accessibility standards vary by country and by the age of a building, contain exceptions, and are enforced by people with authority to interpret them. “Meets the number” and “complies” are different claims, and only one of them can be made by arithmetic.

Nor does any dimension establish that something is safe. Fitting through a doorway and managing that doorway are different questions, and the second one is clinical.

Frequently asked questions

Why does a wheelchair not fit through a wider door?

Two errors that point the same way. The leaf is not the opening — the stop and the open door take 50 to 75mm out of it. And a chair measured across the wheels needs about 50mm more for the hands on the rims. A 760mm door is a 695mm opening, and a 700mm chair needs 750mm.

What is the cheapest way to gain width?

Swing-clear hinges. They move the leaf out of the opening when the door is fully open, recovering most of the hardware loss for very little money, with no work to the frame. Always check these before quoting for structural widening.

How long does a ramp need to be?

At 1 in 12, 1.2 metres of run for every 100mm of height. One ordinary step of 200mm needs 2.4 metres; three steps need over seven, plus landings and flat space at each end.

Which gradient should I use?

It is a judgement, not a rule, so it is an input. 1 in 12 is commonly cited for short assisted ramps; unassisted use generally wants shallower and a powered chair differs again.

Why is the smallest dimension the one that matters for turning?

Because a 180-degree turn needs the circle to fit both ways, so a long narrow room does not help. Where a full circle will not fit, a three-point turn often will and needs much less.

What is the most commonly missed measurement?

The route rather than the destination. A bathroom that works is no use if the hallway to it has a turn that cannot be made. Measure every constriction along the whole journey in order.

Does meeting the figures mean the home is compliant or safe?

No. Codes vary by country and building age, contain exceptions, and are interpreted by people with authority to do so. Meeting a number and complying with a regulation are different claims, and no dimension establishes that anything is safe.