Ventilation commissioning certificate: when you need one and what it must include

In England, when mechanical ventilation is fitted in a home, the Building Regulations ask for a notice to building control that the system has been commissioned. In a new home they also ask for the measured air flow rates, within 5 days of the final test. Approved Document F sets out how to do both, and its Appendix C gives a commissioning sheet. That sheet is what this guide calls the ventilation commissioning certificate. The regulations do not use that name.

This guide follows the 2021 edition of Approved Document F, which applies in England until 24 March 2027. For what the 2026 edition changes, see Part F 2026: what changes for ventilation commissioning.

When you need one

Commissioning: new and existing homes

Regulation 44 covers building work that installs mechanical ventilation, in a new or an existing home. The person doing the work must give the building control authority a notice confirming the system has been commissioned in line with the approved procedure. It does not apply where testing and adjustment are not possible.

Approved Document F says this applies to intermittent extract fans as well as continuous systems (paragraphs 4.1 and 4.2).

The notice is due when the regulation 16(4) notice is due. Where that does not apply, it is due no more than 30 days after the work is finished. For higher-risk building work that needs a completion certificate, it goes to the regulator with the application. Approved Document F says one document can be the commissioning notice for both Part F and Part L.

Air flow rates: new homes

Regulation 42 applies when a new dwelling is created. The air flow rates must be tested in line with the approved procedure, and the results given to building control no later than 5 days after the final test. Approved Document F says every mechanical ventilation fan should be tested (paragraph 4.9):

• intermittent extract fans
• cooker hoods
• continuous extract fans and terminals
• continuous supply fans and terminals.

In England, regulation 42 does not apply to work in an existing home. The Welsh version of the regulation also covers fixed mechanical ventilation fitted or extended in an existing home.

How the air flow is measured

Paragraph 4.10 asks for:

• a calibrated air flow device with a proprietary hood, accurate to within 5%
• calibration in the last 12 months at a calibration centre accredited by UKAS
• every intended background ventilator open, and every internal and external door and window shut
• each fan or terminal's air flow recorded in litres per second.

Each measured rate is compared with its design rate. If every measured rate is equal to or above its design rate, the system meets the design standard. If any is lower, the system is adjusted and every air flow measured again (Appendix C, C2).

For intermittent extract fans, the installer also checks that the fans work, that they respond to their controls, and that any run-on timer is set to at least 15 minutes (paragraph 4.6).

What it must include

As a minimum, the commissioning sheet must hold everything in Part 3 of the example sheet in Appendix C (paragraph 4.3). Appendix C also says all three parts should be completed (C3).

Part 1: system details

• The installation address
• The system classification, manufacturer, model numbers, serial number where there is one, and where each fan unit is
• The installation engineer's name, company, address and phone number
• The commissioning engineer's details, if different, with an email address

Part 2a: installation checklist

• Whether the system was installed to the manufacturer's requirements and to paragraphs 1.12 to 1.83, with details of any departure
• The controls fitted, and where the manual or override controls are
• The installation engineer's signature, registration number if they have one, and the date

Part 2b: inspection before commissioning

• The total installed equivalent area of background ventilators, the floor area of the dwelling, and whether the ventilator area meets the standard
• Whether background ventilators are left open, and whether the right number of extract fans or terminals are in the right places
• Door undercuts, packaging removed, the system clean and reachable for maintenance
• For continuous systems: terminals that allow balancing, insulated and sealed ductwork, the condensate drain on heat recovery units, filters fitted
• Any unusual noise, vibration or smell at start-up or when running

Part 3: commissioning details

• The air flow measuring equipment: model, serial number and the date of its last UKAS calibration
• Intermittent extract fans: measured and design extract rate for each fan. For a cooker hood, only the highest setting is recorded
• Continuous extract: measured and design rates for each room, at high rate and continuous rate
• Heat recovery systems: the same for each supply terminal
• The commissioning engineer's signature, registration number if they have one, and the date of commissioning

One sheet is completed for each installation address, and a copy goes to building control (C4). A copy of the completed sheet also goes to the owner of the home (paragraph 4.14).

Information for the owner

The owner must also be given enough information to run and maintain the system, written for someone who is not technical. Approved Document F says this should include the design flow rates and the maintenance needs, how and when to use each fan setting, and how to clean the system and change filters (paragraphs 4.13 to 4.17). In a new home, the Home User Guide should have a section on ventilation (paragraph 4.18).

Who issues it

The person carrying out the work gives the commissioning notice (regulation 44). The relevant sections of Parts 2 and 3 of the sheet are signed by someone who is competent to install the system and responsible for installing and commissioning it (Appendix C, C3).

Installing a ventilation system in a dwelling is work that a member of a competent person scheme can self-certify. Schedule 3 of the Building Regulations names the scheme operators for it: Blue Flame Certification, Building Engineering Services Competence Assessment, Certsure and NAPIT. A registered installer must, within 30 days of finishing, give the occupier a certificate and give building control either the certificate or a notice of it (regulation 20).

If you are not registered with a scheme, the work goes through building control.

From 24 March 2027

The 2026 edition of Approved Document F comes into force in England on 24 March 2027. Work notified before then keeps the 2021 rules if it starts before 24 March 2028. What it changes is in the Part F 2026 guide.

In CertBox

CertBox's ventilation commissioning certificate follows the 2021 edition, the one in force in England today. Filling it in and checking it is free. Downloading, emailing, sharing or printing it needs Pro, the 14-day trial, or a one-off payment for that certificate. See pricing.

Frequently asked questions

Does one extract fan in an existing home need commissioning?

Under the 2021 edition of Approved Document F, mechanical ventilation must be commissioned and a commissioning notice given to building control, and that includes intermittent extract fans. The 5-day air flow notice under regulation 42 applies to new homes in England.

How long do I have to send the air flow results?

For a new home, no later than 5 days after the final test (regulation 42). The commissioning notice under regulation 44 is due when the regulation 16(4) notice is due, or within 30 days of finishing where that does not apply.

What equipment do I need to measure air flow?

A calibrated air flow device with a proprietary hood, accurate to within 5%, calibrated in the last 12 months at a UKAS-accredited calibration centre (paragraph 4.10 of the 2021 edition).

Does the homeowner get a copy?

Yes. Approved Document F says a copy of the completed commissioning sheet should be given to the owner, along with instructions for running and maintaining the system.

Is the 2026 commissioning sheet in use yet?

Not in England. The 2026 edition of Approved Document F comes into force on 24 March 2027. Until then, the 2021 edition and its sheet apply.

Sources

Checked against these on 2026-11-01.

• Approved Document F, Volume 1: Dwellings, 2021 edition (GOV.UK PDF)
• Building Regulations 2010, regulation 44 (commissioning)
• Building Regulations 2010, regulation 42 (mechanical ventilation air flow rate testing)
• Building Regulations 2010, regulation 20 (competent person schemes)
• Building Regulations 2010, Schedule 3
• The Future Homes and Buildings Standards: Building Circular 01/2026

Corrected and updated 2026-11-01. This article is for general guidance only and does not constitute legal or professional advice. Always refer to the relevant standards and consult qualified professionals for definitive requirements.