AI concept illustration of a ventilation check in a home. This is not a photograph of an actual Marwells project.
When planning a new kitchen, loft bedroom or whole-home refurbishment, ventilation can appear to be a small detail on the electrical plan. It deserves a place in the main design discussion. The position of fans, the route of ducts, the way air reaches each room and the controls you use every day all affect whether the finished arrangement works.
What Part F covers
Part F of the Building Regulations deals with ventilation. In England, Approved Document F gives guidance on meeting the requirements; Volume 1 addresses dwellings. The applicable guidance must be considered alongside the actual building and work being carried out. It is not enough to select a product simply because its brochure mentions Part F. [1]
Ventilation replaces indoor air in a controlled way. Everyday activities introduce moisture and pollutants, and a lack of noticeable odour does not establish that ventilation is adequate. Better airtightness can reduce unwanted draughts, but the planned ventilation system must still suit the home. Energy efficiency and appropriate air movement should therefore be designed together. [2]
Which edition applies 2010 2021 or 2026
As checked on 21 October 2026, the 2026 edition has been published and takes effect from 2027, subject to the commencement dates and transitional arrangements below. [3] Ask your designer or building control body to identify the correct edition and the transitional provisions for your project. The date of a website article or the year in the name 'Building Regulations 2010' does not decide this question. [1]
- Earlier guidance, including the 2010 edition: May remain relevant to work with valid protection under earlier transitional arrangements. It is not an optional route for a new project. [1]
- 2021 edition, Volume 1: Took effect on 15 June 2022. The preceding standards could continue where the relevant notice or full plans were submitted before that date and work started before 15 June 2023. [1]
- 2026 edition, Volume 1: Takes effect on 24 March 2027 for ordinary work, and 24 September 2027 for specified higher-risk building work, subject to transitional arrangements. [3, 4]
For ordinary work, the published 2026 transition generally protects a qualifying notice or full-plans application made before 24 March 2027 if work commences, as defined, before 24 March 2028. Separate provisions apply to higher-risk work. Ask the team to record the relevant route and dates rather than assume that all projects finishing after March 2027 follow the same rules. [4]
Think about three ventilation functions
The designer coordinates whole-dwelling ventilation for everyday air quality, extraction from wet rooms, and purge ventilation for occasional rapid clearance. Purge provision often uses opening windows, while the day-to-day arrangement depends on the selected system. [5]
For a homeowner, a useful way to review a plan is to trace where air enters, how it travels between rooms and where it leaves. Ask what happens with internal doors closed and how the system responds when the shower or kitchen is in use. The answer should describe the complete air path rather than identify a fan in isolation.
Common ventilation options compared
- Background ventilation with intermittent extract: Purpose-provided background air and fans used for extraction in wet rooms; separate purge provision. [5] Questions to resolve: Does the design suit the home, its airtightness and the new room layout?
- Continuous mechanical extract: MEV or dMEV: A central unit extracts through ducts, or individual continuous fans serve wet rooms. [6] Questions to resolve: How will replacement air enter, and what happens at normal and boost settings?
- Mechanical ventilation with heat recovery: MVHR: A coordinated system supplies and extracts air, transferring heat from the outgoing stream to incoming air. [7] Questions to resolve: Where will ducts, terminals, the unit and maintenance access fit? How will it be balanced?
Continuous extract systems need to be planned as an arrangement for the dwelling, whether the fans are centralised or distributed. Several separately purchased fans do not automatically form a coordinated design. Ask the designer to identify the intended normal operation and what changes when additional extraction is needed. [6]
MVHR supplies air to habitable rooms and extracts from wet rooms through a heat-exchange unit. Supply and extract terminals are balanced as part of commissioning. It can be useful where the building and design suit it, but it brings ductwork, controls and maintenance considerations. Do not assume that fitting MVHR means retaining the same background-vent arrangement used for a different system. [7]
Existing homes need a whole property review
An extension can turn an external kitchen into an internal room; a loft conversion adds occupied rooms; replacement windows can change infiltration. The existing dwelling therefore needs attention as well as the new space. The 2026 guidance explicitly addresses work such as adding habitable or wet rooms and reviewing ventilation when energy-efficiency measures reduce infiltration. The project must follow the edition actually applicable to it. [3]
For an illustrative kitchen extension, ask the designer to show how the retained rooms will be ventilated after the rear wall is opened up and the layout changes. If the original extract route is obstructed or moved, identify the replacement before construction starts. For a loft bedroom and en-suite, ask how both rooms fit into the house's ventilation strategy, including the route through the new floor and roof.
Replacement windows and common misunderstandings
Government's Part F FAQs explain that ventilation should not be made less satisfactory by the work. Suitable existing or new wall ventilators may provide the relevant background provision in some circumstances. A window left on a night latch is not an appropriate substitute for a proper background ventilator. A homeowner's disclaimer does not remove the need to meet the requirements. [8]
The same guidance distinguishes ventilation for indoor air quality from combustion-air requirements under Part J. Do not treat an air supply for an open-flued appliance as automatically meeting Part F. In a noisy or polluted location, the design should also consider where outside air is drawn in and how acoustic or pollution issues are addressed. [8]
Plan ducts and access before the ceilings are closed
Ask for the ventilation layout to be coordinated with the structure, lighting, plumbing and joinery. Where are the external terminals? Can the intended duct route be installed without an unplanned change? Can the equipment be reached for maintenance? Who approves alterations when a beam or another service occupies the expected space?
The 2026 guidance places particular emphasis on installation, inspection, testing and information. Its arrangements for work to existing dwellings also address testing of specified new or significantly altered mechanical systems. Those provisions should be applied where that edition governs the work, while earlier projects follow their relevant requirements. [3]
As a practical contract point, request a named person to review the coordinated layout and confirm what will be inspected before covering up. The project programme should leave time to resolve clashes while ducts and connections are accessible. A neat finished grille cannot reveal whether the route behind it matches the design.
Commissioning means proving the installed system works
The 2021 guidance requires mechanical ventilation commissioning and the relevant notice to building control. Mechanical flow rates in new dwellings must be measured and notified. Results are compared with the design, adjusted and rechecked where necessary. Owners also need clear operating and maintenance information. [5]
Ask what testing and records apply to your particular work, including an existing-home installation. Simply switching on a fan proves that it runs; it does not establish that the installed system achieves its design performance. Agree who will carry out commissioning, when it happens and what information you receive before handover.
What should you receive at handover
- An explanation of the ventilation strategy and which rooms each system serves.
- The relevant commissioning and measured-flow records for your installation.
- A demonstration of normal operation, boost controls and any indicators.
- Manufacturer instructions covering cleaning, filters, servicing and safe access.
- Contact details and a clear route for raising performance or noise concerns.
Request a demonstration with the actual controls installed in your home. Ask the contractor to show what you should operate routinely and what should be left at its commissioned setting. If noise makes the system difficult to live with, raise it as an issue to investigate rather than quietly disabling the system and losing the ventilation strategy.
Coordinate ventilation with Marwells
Marwells takes an engineering-led approach to residential construction and refurbishment, bringing structural and building-services coordination into the discussion. Share your extension, loft or refurbishment drawings so we can review the construction scope and the ventilation input required. Contact info@marwells.co.uk or call 07340 094028 to discuss a free quote.
Related: Residential construction · Loft conversions · Retrofit and refurbishment · Get a quote
Sources and further reading
- GOV.UK: Ventilation: Approved Document F
- Energy Saving Trust: Ventilation
- GOV.UK: Approved Document F, Volume 1, 2026 edition, September 2026 revision
- GOV.UK: Future Homes and Buildings Standards: Building Circular 01/2026
- GOV.UK: Approved Document F, Volume 1, 2021 edition
- Vent-Axia: Decentralised mechanical extract ventilation
- Vent-Axia: Mechanical ventilation with heat recovery
- GOV.UK: Approved Document F, Volume 1: frequently asked questions
