What DIN 18040 requires
Lower door stops and thresholds are in principle not permitted. Where they are technically indispensable, they may be at most 2 cm high. The actual goal is the zero threshold – even 2 cm is a noticeable barrier, for example with a walking frame.
The conflict of goals with waterproofing
The waterproofing standards require a protected base above ground level – which seemingly contradicts the zero threshold. The conflict is resolved by controlled drainage directly in front of the door.
How the zero threshold is achieved
A channel with a walkable grating in front of the door – across the full width, connected to the drainage – carries the water away and makes the level transition possible. Sobekon® does exactly that, without backfilling and with clear rear ventilation.
