• For dwelling with multiple floors:
  Habitable rooms and kitchens: 8,000mm2EA
  Bathrooms: 4,000mm2EA
  Sanitary Accommodation: No minimum

• For single storey dwellings (e.g flats):
  Habitable rooms and kitchens: 10,000mm2EA
  Bathrooms: 4,000mm2EA
  Sanitary Accommodation: No minimum

• Seek expert advice should the dwelling have a single exposed façade, or at least 70% of its openings on same façade, or the kitchen has no windows or façade for vents.
• Add the 4,000EA to the total if the bathroom has no window or external façade.
• If kitchen and living room not separate, at least 3 vents of same EA as for habitable rooms should be provided in that space.
• Total number of vents in habitable rooms and kitchen should be at least 5, or 4 if one bedroom property.

• Replacement windows should be fitted with trickle vents regardless of whether the windows being replaced had vents in them or not, if no background ventilation alternative is being installed.
• Habitable rooms and kitchens: 8,000mm2EA, Bathrooms: 4,000mm2EA.
• Addition of a wet room to an existing building: 5,000mm2EA.
• Addition of a habitable room to an existing dwelling (if existing room has less than 5,000mm2EA): 12000mm2EA.
• If the existing dwelling has continuous mechanical extract ventilation fitted then 4,000mm2EA is required in habitable rooms.

• A Home User Guide should be provided for a new dwelling as described in Section 9 of Approved Document L, Volume 1: Dwellings. It should contain a section on ‘Ventilation’ that provides non-technical advice on the ventilation systems provided within the new dwelling.
• The Home User Guide is in addition to the operating and maintenance instructions. It is intended to be a non-technical overview for the occupiers, and should include some basic details on the operation and maintenance of the system. The operating and maintenance instructions provide further details as required.

Additional information for work in existing dwellings (4.20)

• When new ventilation is installed in an existing dwelling, information about it should be provided to the building owner in accordance with paragraphs 4.13 to 4.17.

Go to – https://www.gov.uk/government/publications/home-user-guide-template for the Home Energy Guide Template and the Existing Home Ventilation Guide.

• Sufficient information about the ventilation system and its maintenance requirements must be given to the building owner to allow the system to be operated effectively. This should include both design flow rates and maintenance requirements. The information should be provided in a clear manner, for a non-technical audience.
• A copy of the completed commissioning sheet in Appendix C should be given to the owner of the new dwellings. For existing dwellings Appendix D checklist may be used.
• The operation and maintenance information should contain specific instructions for the end user on how and when to use the ventilation system, including information on the intended uses for the available fan settings. Information should also be provided to suggest when, and how, the system components should be cleaned and maintained.

• Boost Rate – Unchanged
• Floor area rate remains the same = 70m² x 0.3 = 21l/s
• Dwelling bedroom rate now = 31l/s

• Sizing and jointing ducts correctly
• Ensuring that equipment is appropriately and securely fixed
• Selecting appropriate equipment, including following paragraph 1.6