Accessibility: Why Gradient Is Limited
A wheelchair ramp must be designed so that wheelchair users can use it independently and safely. DIN 18040-1 (publicly accessible buildings) and DIN 18040-2 (residential buildings) set the requirements.
The key requirement: the gradient must not exceed 6%. This means: over 1 m of length, the ramp may rise a maximum of 6 cm. For a height difference of 30 cm (e.g., three steps), the minimum ramp length is 5 m.
Key DIN Requirements at a Glance
Maximum gradient: 6% (indoors). Outdoors, many planners recommend a maximum of 4%, as wet or icy surfaces reduce traction.
Maximum run length: 6 m without an intermediate landing. For greater height differences, intermediate landings must be included.
Intermediate landing: minimum 1.50 m long, so that a wheelchair can stand completely on it and turn.
Width: minimum 1.20 m clear width. In public buildings, 1.50 m is frequently recommended to allow passing traffic.
Handrails: on both sides, at 85 cm height, extending 30 cm beyond ramp start and end. Handrails must not protrude into the ramp clearance profile.
Wheel guards: minimum 10 cm high edge on both sides to prevent wheels from slipping off.
Calculating Ramp Length
The formula: Ramp Length (m) = Height Difference (cm) / Gradient (%). Example: 60 cm height difference at 6% gradient: 60 / 6 = 10 m. Since the maximum run length is 6 m, you need at least one intermediate landing.
Division: First ramp 6 m (overcomes 36 cm), intermediate landing 1.50 m, second ramp 4 m (overcomes 24 cm). Total length: 11.50 m. Total height difference: 60 cm.
At 4% gradient (outdoor recommendation): 60 / 4 = 15 m. Division: three ramps of 5 m with two intermediate landings. Total length: 18 m.
Mobile vs. Permanently Installed Ramps
Mobile ramps (wedge bridges, folding ramps) are intended for temporary solutions or small height differences. They may be steeper than 6% if used only with assistance. They are not permitted for permanent use in public buildings.
Permanently installed ramps must meet full DIN requirements. They are typically constructed from concrete, steel, or aluminum. The surface must be non-slip (R10 or better per DIN 51130).
Material Selection and Surface
Concrete ramps are durable and cost-effective but must receive a non-slip surface (broom finish, exposed aggregate, or bonded rubber mats).
Steel ramps with grating are lightweight and offer good traction but can be uncomfortable for wheelchair users due to wheel vibration on the mesh.
Aluminum ramps with ribbed surfaces are the best compromise: lightweight, durable, non-slip, and comfortable to roll on.
Costs of a Wheelchair Ramp
Costs depend heavily on material, length, and complexity. Guide values: mobile wedge bridge (30 cm height): 200-500 euros. Permanently installed aluminum ramp (6 m): 2,000-5,000 euros. Concrete ramp with handrails (10 m): 5,000-15,000 euros including earthworks.
Funding: the nursing care insurance fund covers up to 4,000 euros for home modification measures (which includes ramps) for those with a care level. Additional state-level funding programs from KfW and municipalities may be available.