My husband and I live in a purpose built flat,there are five flats 1 on ground floor 2 on first floor,one is mine,2 on top floor ,I have asked our managing agent if it’s possible to have a stair lift as my husband has bad Arthritis,they said health and safety said it would be a fire hazard? The stairs are 42” wide can you advise please. Also what is the  safe height of a door step please? Is there legal size.

GENERAL ADVICE AND GUIDELINES

A stair-lift should not be installed in a single stairway building if it causes an unacceptable restriction in width to the only available route of escape.

The stairway width required for means of escape should be maintained beyond the incursion into the stairway width of any fixed part of the stair-lift such as the carriage rail.

The effect of other parts of the installation on the width of the escape routes should also be considered e.g. the power unit and the stair-lift itself when in the closed position.

I am assuming there is only one communal staircase therefore it is not acceptable and the minimum  escape width would be 30 inches leaving 12 inches for the stair lift which in my experience would be not sufficient.