Minimum dimensions at home: doors, stairs, ceilings

Last updated: 26 October 2026

In Germany, a stair in a house with one or two flats needs at least 80 cm of usable width, a rise of 14 to 20 cm and a going of 23 to 37 cm under DIN 18065, and the step rule 2r + g should come to 59 to 65 cm. Habitable rooms must be at least 2.40 m high under most state building codes, 2.30 m in Baden-Württemberg, with exceptions for attic storeys and small residential buildings. For barrier-free design to DIN 18040-2 you need clear manoeuvring areas of 120 × 120 cm, or 150 × 150 cm for wheelchair users.

Where minimum dimensions come from

In Germany, minimum dimensions come from two sources:

State building codes (Landesbauordnungen): building law is a matter for the 16 states. Each has its own code, based on the Model Building Code (Musterbauordnung, MBO) of the state building ministers but differing in detail. These requirements are law.
DIN standards such as DIN 18065 for stairs or DIN 18040-2 for barrier-free flats. On their own they are recognised rules of good practice. They become binding when a state introduces them as technical building regulations, when a subsidy requires them, or when they are agreed in the building contract.

Existing buildings are often judged differently from new ones. For conversions, the building authority can allow deviations. When in doubt, ask your local building authority.

Doors

Inside a flat, the Model Building Code sets no door width. In practice, sizes follow DIN 18101. It defines structural opening sizes based on a 12.5 cm grid:

Structural opening (nominal)	typical use
63.5 × 200.5 cm	storage room, small WC
76 × 200.5 cm	bathroom, secondary room
88.5 × 200.5 cm	standard room door
101 × 200.5 cm	wide door, barrier-free
113.5 × 200.5 cm	very wide door

The door leaf is slightly narrower than the opening, and the clear passage through the frame narrower still. For barrier-free design, plan with the clear dimension, not the structural one.

There are fixed requirements in a few places:

Entrance doors to flats that must be reachable by lift need a clear width of at least 0.90 m under the MBO.
Windows that serve as the second escape route must have a clear opening of at least 0.90 × 1.20 m.
For barrier-free design to DIN 18040-2, doors inside the flat need at least 80 cm clear width, 90 cm in wheelchair-accessible flats. The clear height should be at least 205 cm.

Hallways

The Model Building Code does not require "necessary corridors", which come with width rules, inside flats or in residential buildings of building classes 1 and 2. So there is usually no legal minimum width for the hallway in your flat.

The only fixed figure comes from DIN 18040-2: hallways in barrier-free flats are at least 120 cm wide. In wheelchair-accessible flats the hallway also needs at least one spot of 150 × 150 cm for turning. Allow for what stands in the hallway: with a 40 cm deep coat rack on the wall, 120 cm leaves 80 cm to walk.

Stairs to DIN 18065

DIN 18065 "Gebäudetreppen" (building stairs, current edition 2020) distinguishes whether a stair is required by building law, meaning it gives access to a storey, or is an additional stair. The limits apply to the finished stair:

Stair	usable width	rise r	going g
residential buildings with up to two flats and inside flats, required	min. 80 cm	14–20 cm	23–37 cm
other buildings, required	min. 100 cm	14–19 cm	26–37 cm
additional (not required) stair	min. 50 cm	14–21 cm	21–37 cm

In addition:

Step rule: 2r + g = 59 to 65 cm. It makes the stair match a normal stride.
Clear headroom: at least 200 cm above the stair. In houses with one or two flats it may be slightly lower at the edge.
Handrail: under the MBO, stairs must have a fixed handrail that is easy to grip.
Guarding: under the MBO, areas next to a drop of more than 1 m must be guarded. For a fall height up to 12 m the guard is at least 0.90 m high, above that 1.10 m.

Worked example

The height from floor to floor is 2.75 m. With 16 risers, each step is 275 ÷ 16 ≈ 17.2 cm high. The step rule with a comfortable 63 cm gives the going: 63 − 2 × 17.2 = 28.6 cm. A straight stair has one going fewer than risers, so 15 × 28.6 cm ≈ 4.29 m of run in plan. Both values are within the limits for residential buildings.

The stair calculator does this for you. In RoomPlanning, the stair tool also works out risers and goings from the storey height (Storeys, stairs and roofs).

Room heights under German state building codes

The Model Building Code requires a clear room height of at least 2.40 m for habitable rooms, meaning living rooms, bedrooms, children's rooms, studies and kitchens. In the roof space, 2.20 m over at least half of the net floor area is enough, and parts of the room under 1.50 m high are left out. Under the MBO this requirement does not apply to residential buildings of building classes 1 and 2. Simplified, these are buildings up to 7 m high with at most two flats totalling no more than 400 m².

The states implement this differently:

State	Habitable rooms	In the roof space
Model Building Code	2.40 m, not for residential buildings of building classes 1 and 2	2.20 m over at least half the area
Baden-Württemberg (§ 34 LBO)	2.30 m	2.20 m over at least half the floor area
Bavaria (Art. 45 BayBO)	2.40 m, not for residential buildings of building classes 1 and 2	2.20 m over half the usable area

In all three cases, parts of the room under 1.50 m are disregarded. Other states have similar but not identical rules. Check your state's building code or ask the building authority.

Don't confuse these values with the living area calculation: the WoFlV counts areas from 2 m height in full, but whether a room is permitted as a habitable room is a matter for the building code. More in the guide Calculating living area.

Barrier-free to DIN 18040-2

DIN 18040-2 (2011 edition) distinguishes barrier-free usable flats from flats that are fully usable by wheelchair (marked R). Manoeuvring areas may overlap.

Area	barrier-free usable	wheelchair-accessible (R)
manoeuvring area in living rooms, bedrooms and kitchen	120 × 120 cm	150 × 150 cm
in front of WC, washbasin, shower, bath	120 × 120 cm	150 × 150 cm
in front of the kitchen units	120 cm deep	150 cm deep
along the bed	120 cm on one long side, 90 cm on the other	150 cm on one long side, 120 cm on the other
in front of other furniture	90 cm deep	150 cm deep
hallway	120 cm wide	120 cm, at least once 150 × 150 cm
doors inside the flat, clear width	80 cm	90 cm

Which furniture clearances work well in everyday life, even without barrier-free requirements, is covered in the guide Furniture clearances.

Checking minimum dimensions in RoomPlanning

With the measure tool (M key) you quickly check in RoomPlanning whether a hallway is wide enough. You place doors at the right width, and on the eye-level walkthrough you notice straight away if a spot gets tight (Walkthrough together).

Frequently asked questions

How high must a living room be at minimum?

Under the Model Building Code and many German state codes 2.40 m, in Baden-Württemberg 2.30 m. Lower values apply over part of the area for rooms in the attic. For small residential buildings of building classes 1 and 2, the MBO and Bavaria set no fixed minimum height.

How wide must a stair in a single-family house be?

A required stair needs at least 80 cm of usable width under DIN 18065. That is the width between wall and handrail or between handrails, not the length of the step.

What door do I need for a wheelchair?

For wheelchair-accessible flats, DIN 18040-2 requires at least 90 cm clear width. You only get that with a wider opening than the standard 88.5 cm room door, for example 101 cm in the shell.

What does the step rule mean?

It links rise and going to stride length: twice the rise plus the going should come to 59 to 65 cm. With an 18 cm rise, a going of 23 to 29 cm fits.

Sources

This guide is general information and is not legal or planning advice.