Quality.
    Minimum
    England

    Cistern access requirements

    520 mm

    Adequate access must be provided to cold water storage cisterns located in roof spaces and voids, through an opening of at least 520mm in each direction

    Adequate access must be provided to cold water storage cisterns located in roof spaces and voids, through an opening of at least 520mm in each direction. Access points should not be in hazardous locations and a minimum 1m² platform is required for safe maintenance.

    Basis in regulation

    How to check it on site

    Ensure access hatches meet size requirements and that a safe, stable platform is present for maintenance of the cistern.

    Common failure

    Insufficient access opening size or lack of a safe working platform, hindering future maintenance.

    Last updated 23 August 2026. This is our editorial summary of publicly available regulation, not building control approval or a warranty determination.

    Related dimensions at this stage

    Minimum

    Hearth Provision and Floor Finishes

    225 mm

    A hearth may not be necessary if an appliance's flame or incandescent material is positioned at least 225mm above the floor

    Minimum

    Soundproofing Measures for Soil Pipes

    25 mm

    Sound insulation for soil pipes involves either encasing them in boxing made from a material with a minimum mass of 15kg/m², or wrapping them with at least 25mm of unfaced mineral wool, typically 10kg/m³ density

    Minimum

    Electrical Accessory Clearance from Water Diagrams

    300 mm

    Diagrams illustrating the required 300mm minimum horizontal clearance for electrical accessories from water sources, such as sinks and wash basins, are commonly used in guidance documents

    exact

    Conditions for Pipe Freezing Calculations

    6 °C

    Calculations for pipe insulation to prevent freezing are based on specific assumed conditions, typically including an external air temperature of -6°C and an internal water temperature of +7°C

    Minimum

    Water seal depth at appliance traps

    75 mm for baths, basins, sinks and showers on a branch; 50 mm for a WC trap

    Appliance trap on a branch discharge pipe

    Minimum

    Stair Handrail Height and Clearance

    600 mm

    A handrail is mandatory for flights of stairs where the rise exceeds 600mm