Accessible clearances for homes

What applies to a house, and what does not#

The 2010 ADA Standards for Accessible Design are a civil rights instrument for public life: shops, restaurants, offices, government buildings. They do not reach into a private house. Neither does ICC A117.1, except where a jurisdiction adopts it for particular building types.

What does reach housing in the US is the Fair Housing Act, whose design and construction requirements apply to covered multifamily dwellings first occupied after 13 March 1991. In broad terms that means all ground floor units in buildings of four or more units, and all units in buildings served by a lift. The FHA requirements are lighter than the ADA: an accessible route into and through the dwelling, doors usable by a person in a wheelchair, an accessible route to switches and outlets, reinforced bathroom walls for later grab bars, and kitchens and bathrooms with enough space to manoeuvre.

In the UK the equivalent split is Approved Document M Volume 1, where M4(1) is the baseline for new dwellings, M4(2) covers accessible and adaptable dwellings, and M4(3) covers wheelchair user dwellings. The higher two apply only when a planning condition requires them.

So for a private house, the correct framing is: these numbers are not law, they are the best-evidenced dimensions available, and most of them cost nothing at design stage and a great deal to retrofit.

The core numbers#

Item	Dimension	Metric	Reference
Clear door width	32 in	81 cm	ADA 404.2.3
Route width, sustained	36 in	91 cm	ADA 403.5.1
Route width, up to 24 in long	32 in	81 cm	ADA 403.5.1
Turning circle	60 in diameter	152 cm	ADA 304.3.1
T-shaped turning space	60 x 60 in, arms 36 in	152 x 152 cm	ADA 304.3.2
Clear floor space	30 x 48 in	76 x 122 cm	ADA 305.3
Forward reach, high and low	48 in and 15 in	122 cm and 38 cm	ADA 308.2
Work surface height	28 to 34 in	71 to 86 cm	ADA 902.3
Knee clearance	27 in high, 30 in wide, 11 to 25 in deep	69, 76, 28 to 64 cm	ADA 306.3
Toe clearance	9 in high, up to 6 in deep	23 cm, 15 cm	ADA 306.2
Grab bar height to top of bar	33 to 36 in	84 to 91 cm	ADA 609.4
Toilet centreline from side wall	16 to 18 in	41 to 46 cm	ADA 604.2
Roll-in shower	30 x 60 in minimum	76 x 152 cm	ADA 608.2.2

Doors, routes and turning#

32 in clear, not 32 in nominal. Clear width is measured between the face of the door open at 90 degrees and the stop on the opposite jamb, which is about 2 in (5 cm) less than the leaf you buy. Specify 36 in (91 cm) leaves throughout and the problem disappears. The full breakdown, including the 18 in (46 cm) of latch-side wall needed to pull a door open from a seated position, is in door sizes, swings and the space they need.

36 in routes are the same number as the IRC hallway minimum, which is convenient: a code-compliant hallway is already a compliant route. Where the route makes a 180 degree turn around an obstruction narrower than 48 in (122 cm), the approach legs widen to 42 in (107 cm) and the turn to 48 in (122 cm). See hallway widths that work.

60 in turning. The turning circle is the number that decides room sizes. It does not have to be 60 in of bare floor: part of it may pass under a basin, a worktop or a table where knee and toe clearance exists. That single allowance is what makes accessible bathrooms possible in ordinary footprints.

Clear floor space: the habit worth forming#

30 x 48 in (76 x 122 cm) is a stationary wheelchair. Draw that rectangle at every point of use: in front of the basin, beside the bed, at the hob, at the fridge, in front of the wardrobe, under the window you want to open. Up to 19 in (48 cm) of the rectangle may extend under a fixture where knee and toe clearance exists.

This is a more revealing exercise than checking route widths, because routes are usually fine and points of use usually are not. A kitchen with 42 in (107 cm) aisles can still be unusable if the only clear floor space at the oven is blocked by an open dishwasher door.

Reach, heights and controls#

The reach range is 15 to 48 in (38 to 122 cm) above the floor. Below 15 in and above 48 in, a seated user cannot reach reliably. This one range determines more than it appears to:

• Light switches at 42 to 48 in (107 to 122 cm), not the customary 52 in (132 cm)
• Sockets at 15 to 18 in (38 to 46 cm), not the customary 12 in (30 cm)
• Thermostats and intercoms no higher than 48 in (122 cm)
• The top usable shelf of a wall cabinet at 48 in, which is below the standard 54 in (137 cm) underside of a kitchen wall unit, so wall cabinets serve mainly as storage for others
• Wardrobe hanging rails at 48 in (122 cm) maximum, which suits a single-hang arrangement rather than the double-hang used in closet dimensions

Where the reach is over an obstruction such as a counter, the maximum drops: reaching over a 24 in (61 cm) deep counter, the high reach falls to about 44 in (112 cm).

Counters, knees and kitchens#

A standard kitchen counter is 36 in (91 cm) high. A seated user needs 34 in (86 cm) maximum with knee clearance under it: 27 in (69 cm) high at the front edge, 30 in (76 cm) wide, and 11 to 25 in (28 to 64 cm) deep, with a 9 in (23 cm) toe space below.

The practical move in a private house is not to lower the whole kitchen. It is to build one 36 in (91 cm) wide section of run at 34 in with an open front, next to the hob and next to the sink, and to keep the rest at standard height. That gives a seated user a proper work surface and a standing user an unchanged kitchen, at the cost of one cabinet. Standard heights to design the exception against are in counter and cabinet heights.

Two more kitchen details that cost nothing at design stage: put the oven in a wall housing with its floor no higher than 34 in (86 cm) rather than under the counter, and specify a side-opening oven door, because a drop-down door pushes the user 20 in (51 cm) back from the shelf.

Bathrooms#

The bathroom is where the numbers bind hardest, because fixtures are fixed and the room is small.

• Toilet centreline 16 to 18 in (41 to 46 cm) from the side wall. Use 18 in.
• Grab bars with their top edge 33 to 36 in (84 to 91 cm) above the floor. A side wall bar at least 42 in (107 cm) long, a rear wall bar at least 24 in (61 cm) long.
• Clear floor space beside the toilet for a lateral transfer, ideally the full 60 in (152 cm) width so the approach side is not fixed at design stage.
• A roll-in shower at least 30 x 60 in (76 x 152 cm) with a clear space along its open face 30 in (76 cm) deep and 60 in (152 cm) long, so the chair can be squared up and reversed in. A transfer shower is 36 x 36 in (91 x 91 cm) with a 36 x 48 in (91 x 122 cm) clearance.
• A basin at 34 in (86 cm) maximum rim height with knee clearance under, which rules out a pedestal and most vanity units. Wall-hung is the answer.

The order to build accessibility in#

1. Route. One level entry, 36 in (91 cm) minimum route from the entrance to a bathroom, a bedroom and the kitchen. If the house is on two floors, the route is on one of them.
2. Doors. 36 in leaves on that route, with 18 in (46 cm) of latch-side wall on the pull side.
3. Approach depths. 48 in (122 cm) in front of every fixture on the route, in place of the standard 36 in.
4. One turning space per room on the route, using knee clearance under fixtures to make the 60 in circle fit.
5. Reach. Switches down, sockets up, one 34 in (86 cm) work surface, one hanging rail at 48 in (122 cm).
6. Blocking and future-proofing. Plywood behind bathroom walls, a stair with a straight flight where a lift could later be fitted, and a hall cupboard positioned so it could take a through-floor lift.

Steps 1 to 3 make a house usable. Steps 4 to 6 make it usable without renovation when circumstances change, which is the whole point: the majority of people who need these dimensions do not need them on the day they move in.