The German standard for barrier-free building design and compliance auditing.

DIN 18040 does not use a numerical condition score. Instead, every audited element receives a compliance status that compares its measured value against the standard's threshold. A door with a clear width of 92 cm is Compliant because DIN 18040-1 requires a minimum of 90 cm. A door at 88 cm may be classified as Conditionally Compliant if it still meets the protection goal (Schutzziel) despite the minor deviation. A door at 75 cm is Non-Compliant because it presents a definitive barrier to wheelchair users. This three-level system replaces the graduated scales found in condition assessment standards with a pass/conditional/fail framework that directly maps to regulatory enforcement.

The compliance status is determined individually for each inspected element, not for the building as a whole. A building may have compliant entrances but non-compliant sanitary facilities, or compliant ramps but missing tactile guidance systems. The audit report therefore produces a per-element compliance matrix that identifies exactly where barriers exist and what remediation is needed. In the digital form, the inspector selects the Compliance Status from three options: "Konform (Compliant)," "Bedingt Konform (Cond. Compliant)," and "Nicht Konform (Non-Compliant)." An additional usability scale from A (Very Good) to E (Defective) can capture the physical condition of compliant elements — a ramp may meet the 6% slope threshold but have a deteriorated surface that affects practical usability.

An accessibility audit begins before the building is reached. DIN 18040-3 defines the requirements for public traffic and open spaces (Öffentlich zugängliche Verkehrs- und Freiflächen), covering the routes that connect public transport stops, parking areas, and street crossings to building entrances. The standard requires a minimum clear width of 150 cm for pathways, allowing two wheelchair users to pass each other. At bottleneck points, the minimum reduces to 90 cm for short stretches only. The surface material is a critical compliance factor: asphalt and concrete pavers with joints under 5 mm are compliant, while loose gravel and rough natural cobblestone automatically fail because they create rolling resistance that prevents wheelchair propulsion. In the form, the inspector selects the Surface Material from six options, and selecting "Cobblestone (Rough/Natural)" or "Gravel (Loose)" triggers an automatic non-compliant flag.

Longitudinal slope is limited to a maximum of 6%, and cross slopes (Querneigung) must not exceed 2% to prevent lateral drift of wheelchairs. These values are measured with a digital inclinometer and recorded as percentages. The standard also mandates tactile guidance systems (Bodenindikatoren) conforming to DIN 32984. These include ribbed plates (Leitstreifen) for directional guidance and studded plates (Aufmerksamkeitsfelder) for warning at hazard points such as platform edges and street crossings. The form records whether a tactile guidance system is present as a boolean field, and if present, the inspector documents the specific profile type. Resting areas with seating must be provided at intervals no greater than 100 meters along extended pathways, accommodating users who cannot sustain continuous locomotion.

Tactile guidance systems referenced in DIN 18040-3 follow the specifications of DIN 32984 (Bodenindikatoren).

Vertical circulation is the single most common point of failure in accessibility audits. DIN 18040-1 requires that every level change be navigable without steps, meaning that ramps or lifts must be provided wherever stairs exist. The standard does not accept stairs as a compliant vertical circulation element on their own — they must always be accompanied by a step-free alternative. Ramps must have a maximum inclination of 6%, a clear width of at least 120 cm, and a maximum run length of 600 cm before a level landing is required. Wheel deflectors (Radabweiser) of at least 10 cm height must line both sides to prevent wheelchairs from rolling off the edge. Handrails are required on both sides at a height between 85 and 90 cm, and the profile must be grippable — round with a diameter of 3 to 4.5 cm or oval.

Staircases, while not independently compliant for vertical access, must still meet specific safety requirements. Open risers (offene Setzstufen) and undercut designs are classified as non-compliant because they create trip hazards and disorientation for visually impaired users. Step markings (Stufenmarkierungen) are mandatory: a continuous contrast strip on the step edge provides visual orientation, with the preferred implementation being full step contrast rather than a partial side-only marking. In the digital form, the inspector records each vertical circulation element separately — the Element Type dropdown offers "Ramp (Rampe)," "Staircase (Treppe)," and "Lift (Aufzug)." The clear width, inclination, handrail configuration, and step marking fields adapt based on the selected element type. Each element receives its own compliance status, producing a granular record that identifies exactly which circulation elements present barriers.

Lifts (Aufzüge) must provide a minimum cabin size of 110 cm by 140 cm, with door openings of at least 90 cm. Control panels must be reachable from wheelchair height (85 to 105 cm) and equipped with tactile and Braille markings. Voice announcement of floor levels satisfies the acoustic component of the Two-Senses Principle for lift operation.

The Zwei-Sinne-Prinzip (Two-Senses Principle) is what makes DIN 18040 fundamentally different from other building inspection standards. While most standards evaluate physical dimensions and structural conditions, DIN 18040 requires that every information channel — signage, wayfinding, warnings, and controls — be perceivable through at least two of three sensory modalities: sight (Sehen), hearing (Hören), and touch (Tasten). A visual sign must be accompanied by either a tactile equivalent (Braille, pyramid letters) or an acoustic equivalent (voice announcement). A fire alarm bell must be paired with a visual strobe. An elevator floor indicator display must include both a voice announcement and a tactile button layout. This principle ensures that no single sensory impairment can completely exclude a person from receiving critical information.

In the audit form, the Two-Senses Principle is evaluated through three interconnected field groups. Visual Contrast is measured using the Michelson contrast formula and classified as High (Michelson > 0.7), Fair (Michelson > 0.4), or Low/None. The Michelson contrast ratio compares the difference between maximum and minimum luminance values divided by their sum — it is the German standard's preferred measurement method over the simpler Weber contrast used in some other national standards. The Tactile Information field is a multi-select capturing which tactile media are present: Braille, Pyramid/Relief Letters, and Tactile Floor Indicators (Bodenindikatoren). The Acoustic Information field captures the presence of Induction Loops (for hearing aid users), PA Systems, and Visual Fire Alarms (strobes). An element that provides information through only one sense — for example, a sign with text but no Braille and no audio equivalent — violates the Two-Senses Principle regardless of how well it performs on that single channel.

The practical challenge of the Two-Senses Principle is that it applies not just to dedicated information displays but to every navigational element in the building. Floor-level changes must be communicated visually (contrast markings on step edges) and tactilely (tactile floor indicators at the top and bottom of staircases). Room identification must be visual (signage) and tactile (raised lettering or Braille). Emergency exits must be visual (illuminated signs) and acoustic (alarm announcements). The audit therefore checks the Two-Senses compliance at every transition point, not just at designated information stations. This cross-cutting nature is why the digital form includes sensory fields in multiple sections rather than confining them to a single orientation block.

For comparable accessibility requirements in the United States, see the ADA Accessibility Standards.

Accessible sanitary facilities are among the most dimensionally prescriptive elements in DIN 18040-1. The standard requires a turning circle (Bewegungsfläche) of at least 150 cm diameter within the WC room, enabling a wheelchair user to turn completely. The WC seat height must be between 46 and 48 cm — a narrow band that accommodates lateral transfer from a wheelchair. Transfer spaces of at least 90 cm must be provided on both sides of the WC, with foldable grab bars (Stützklappgriffe) on both sides mounted at the correct height. The grab bars must be foldable so they can be swung up out of the way during transfer and lowered for support during use. In the form, grab bar configuration is recorded as None, Left Only, Right Only, or Both Sides (Foldable), and only "Both Sides (Foldable)" is considered fully compliant.

The emergency call system (Notruf) is a critical and frequently failed element. DIN 18040-1 requires that the emergency call trigger be reachable from the floor — meaning a person who has fallen from the WC or wheelchair must be able to activate it while lying down. A wall-mounted switch at 85 cm height does not meet this requirement. The form captures the emergency call system with three options: "Compliant (Reachable from floor)," "Non-Compliant (Too high/Unreachable)," and "Missing." The washbasin must be wheelchair-accessible (unterfahrbar), meaning sufficient knee space underneath for a wheelchair user to roll up directly to the basin. The mirror must be viewable from a seated position, either through a tiltable mounting or a tall mirror with a low lower edge. Each sanitary room is documented individually in a repeatable form section because buildings typically contain multiple accessible WC facilities, and compliance may vary between them.

The requirements for accessible sanitary facilities are defined in DIN 18040-1 Section 5.7. Explore all available inspection standards in the standards library.