Approved Document F Ventilation, Volume 1: Dwellings – Building Regulations 2010 Guidance
Approved Document F, Volume 1: Dwellings provides statutory guidance on meeting the requirements of Part F of Schedule 1 to the Building Regulations 2010. This 2021 edition, issued by HM Government, is for use in England and took effect on 15 June 2022. It sits under the legal framework established by the Building Act 1984 and replaces previous versions of Approved Document F for domestic buildings.
The scope of this document is limited to dwellings, defined as self-contained units designed to accommodate a single household. It details the technical performance requirements for Requirement F1: Means of ventilation, as well as compliance with Regulations 39, 42, and 44. The document outlines a comprehensive ventilation strategy involving extract ventilation, whole dwelling ventilation, and purge ventilation. It addresses the installation, commissioning, and maintenance of various systems, including natural ventilation, continuous mechanical extract ventilation (MEV), and mechanical ventilation with heat recovery (MVHR).
The following sections detail specific technical standards for ventilation rates, pollutant control, and requirements for work carried out on existing buildings.
Ventilation Strategy and Performance Rates
The ventilation strategy relies on three elements to protect occupant health and prevent mould or internal air pollution.
- Extract Ventilation: Used to remove water vapour and pollutants at source in rooms such as kitchens, bathrooms, utility rooms, and sanitary accommodation.
- Whole Dwelling Ventilation: Provides continuous outdoor air supply to dilute and remove pollutants not addressed by extract ventilation.
- Purge Ventilation: Facilitates the rapid dilution of high concentrations of pollutants or water vapour, typically through large openings like windows or doors.
Minimum extract rates are specified based on the type of room and whether the system is intermittent or continuous. For intermittent extract systems, the following rates apply:
- Kitchen: 30 litres per second (l/s) if a cooker hood extracts to the outside, or 60 l/s otherwise.
- Utility Room: 30 l/s.
- Bathroom: 15 l/s.
- Sanitary Accommodation: 6 l/s.
Minimising Ingress of External Pollutants
Section 2 requires ventilation systems to be designed to limit the intake of outdoor air pollutants if the building is located near significant pollution sources or if local air quality exceeds specific limits.
- Pollutant Limits: Exposure limits are defined for Carbon monoxide, Sulphur dioxide, Nitrogen dioxide, Benzene, and particulate matter (PM2.5 and PM10).
- Intake Location: Ventilation intakes should be located away from direct local pollution sources, such as busy urban roads or industrial discharges.
- Exhaust Outlets: Outlets must be positioned to prevent the re-entry of exhaust air into the building or nearby structures.
Work on Existing Dwellings
When building work is performed on an existing dwelling, the ventilation must either meet the standards of the approved document or not be less satisfactory than before the work was carried out.
- Energy Efficiency Measures: Adding insulation or draught-proofing can reduce infiltration. A simplified method (Diagram 3.1) categorises the impact of such work into Category A, B, or C to determine if additional ventilation is necessary.
- Replacing Windows: If the original windows had background ventilators, the replacements must include ventilators of at least the same size. If the originals lacked them, replacements should generally include ventilators (e.g., 8000mm2 equivalent area for habitable rooms).
- Additions: New habitable rooms, wet rooms, or conservatories (exceeding 30m2) must meet specific ventilation standards for both extract and whole-dwelling supply.
Commissioning and Information Provision
Regulations 39, 42, and 44 mandate that ventilation systems are correctly tested, commissioned, and documented for the building owner.
- Air Flow Rate Testing: Mechanical ventilation systems in new dwellings must have their air flow rates measured using a calibrated device and results must be notified to the building control body within five days of testing.
- Commissioning: Fixed systems must be commissioned by testing and adjustment to ensure they meet the design criteria.
- Information Provision: Owners must receive sufficient information to operate and maintain the system, often provided via a Home User Guide and a completed commissioning sheet.
Frequently Asked Questions
When did the 2021 edition of Approved Document F Volume 1 come into effect?
The document took effect on 15 June 2022 for use in England, subject to transitional arrangements for work started before 15 June 2023.
What is the minimum door undercut required for air transfer between rooms?
Internal doors should provide a minimum free area equivalent to a 10mm undercut in a 760mm wide door, measured above the floor finish.
Are conservatories exempt from the ventilation requirements of Part F?
Conservatories with a floor area that does not exceed 30m2 are exempt from the Part F requirements.
What is the required height for background ventilators to avoid draughts?
Background ventilators should generally be at least 1700mm above floor level to reduce cold draughts while remaining accessible.
How is the 'equivalent area' of a background ventilator measured?
It is the area of a sharp-edged circular orifice through which air would pass at the same volume flow rate under an identical pressure difference, determined at 1Pa.
What are the ventilation requirements for a new habitable room added to an existing dwelling?
The room requires purge ventilation and background ventilation (typically at least 10,000mm2 equivalent area) if it is connected to an existing room that now lacks windows.
Does the document provide guidance on tobacco smoke or vaping products?
No, the guidance in Approved Document F is not designed to deal with the products of tobacco smoking or vaping.
