Building Regulations Approved Document 'M' routes from the exterior across the threshold
should provide weather protection without presenting a barrier for
wheelchair access or a trip hazard to other users. A level threshold is preferred, especially for doors in frequent
Doorsets that have been designated as fire and smoke resisting must continue to provide full protection but not require excessive opening effort - one way to meet this requirement is to use automatic doors and / or use low opening force seals.
We supply low profile threshold plates, manufactured by Raven, that make wheelchair access smoother and easier and matching door seals offering a low opening resistance but with fully certified fire, smoke and weather sealing properties.
More information here: http://www.draftproofing.com/raven_threshold_plates.html