As modern homes become increasingly airtight and energy efficient, effective ventilation has never been more important. While improved insulation helps reduce energy consumption, it also means that moisture, pollutants and stale air can become trapped inside a property if ventilation systems are not performing correctly.

To ensure homes provide a healthy indoor environment, Approved Document F of the Building Regulations requires ventilation systems to be tested and commissioned before a building can be signed off.

What is Extractor Fan Testing?

Extractor fan testing measures the airflow performance of intermittent extract fans, such as those installed in kitchens, bathrooms and WCs, to ensure they meet the minimum ventilation rates specified in Approved Document F.

For new dwellings, the measured airflow rates must be submitted to Building Control before completion and handover.

At our company, we can carry out extractor fan testing alongside air tightness and sound insulation testing during the same site visit. This not only simplifies project coordination but also reduces costs and helps keep your build programme on schedule. As a UKAS-accredited company, you can be confident that all testing is carried out to the highest industry standards.

Why is Extractor Fan Testing Required?

Today’s homes are designed to minimise heat loss, making them significantly more airtight than older properties. Without adequate ventilation, moisture can build up, leading to condensation, mould growth and poor indoor air quality.

Approved Document F requires both:

• Mechanical Ventilation with Heat Recovery (MVHR) systems
• Intermittent extractor fans (such as kitchen and bathroom fans)

to be tested and commissioned to verify that they are operating efficiently and achieving the required airflow rates.

The results form part of the Building Regulations compliance process and are required before final approval can be issued.

Combining Part F and Part L Testing

Where possible, we carry out ventilation flow rate testing at the same time as your air pressure (air tightness) test.

This provides several benefits:

• Reduced site visits
• Lower overall testing costs
• Easier project coordination
• Faster Building Regulations compliance
• Minimal disruption to your construction programme

Understanding the Four Ventilation Systems

Approved Document F identifies four main types of domestic ventilation systems.

System 1 – Background Ventilation with Intermittent Extract Fans

This is the most common system used in UK homes.

Fresh air enters through trickle vents in windows or background ventilators, while intermittent extractor fans remove moisture and odours from kitchens, bathrooms and utility rooms.

System 2 – Passive Stack Ventilation (PSV)

Passive Stack Ventilation relies on natural air movement created by wind pressure and thermal buoyancy.

Air enters through background ventilators and exits via passive roof terminals without the need for powered extract fans.

System 3 – Continuous Mechanical Extract Ventilation (MEV)

Mechanical Extract Ventilation continuously removes stale air from wet rooms using a central mechanical extract system.

Fresh air enters the property through background ventilators.

System 4 – Mechanical Ventilation with Heat Recovery (MVHR)

MVHR systems continuously extract stale air while supplying filtered fresh air throughout the property.

A heat exchanger recovers warmth from the outgoing air and transfers it to the incoming fresh air, improving energy efficiency while maintaining excellent indoor air quality.

Minimum Extract Rates

Approved Document F specifies the minimum airflow rates that extractor fans must achieve.

If your ventilation system fails to achieve these airflow rates, remedial work may be required before Building Control approval can be granted.

Preparing for Extractor Fan Testing

To ensure testing can be completed successfully, the following should be in place before our engineer arrives:

• Electrical power connected to all extractor fans
• All fans fully operational
• Doors and windows installed
• Window trickle vents fitted where required
• Internal doors installed
• Walls, ceilings and floors completed
• Air barrier fully sealed around all ventilation terminals
• Safe access to every extract point
• Parking available within 50 metres of the property

We also require:

• SAP calculation worksheets
• Ventilation system specifications
• Floor plans and sections (at least three days before testing)
• Occupancy schedule for each dwelling

Installation Best Practice

Correct installation is just as important as selecting the right ventilation system. Before testing, it’s worth checking that:

• Ductwork matches the manufacturer’s specification.
• Duct runs are as short and straight as possible to minimise resistance.
• Flexible ducting is only used where recommended.
• All duct joints are correctly sealed.
• Ventilation penetrations maintain the building’s airtightness.
• Fans are securely fixed and correctly adjusted.
• Internal doors have approximately 10mm undercuts where required.
• Fan speeds have been commissioned using the manufacturer’s guidance.
• Air handling units are securely mounted.
• Adequate access has been provided for future maintenance.

Attention to these details can significantly improve airflow performance and reduce the likelihood of failing a compliance test.

Expert Advice and Testing Services

Whether you’re building a single dwelling or managing a larger residential development, we provide professional guidance to help you achieve compliance with Approved Document F.

Our experienced consultants can advise on ventilation systems, testing requirements and the most efficient way to combine extractor fan testing with air tightness and acoustic testing, helping you save both time and money.

If you have any questions about domestic ventilation testing or would like to arrange a site visit, get in touch with our team today by calling 01525 303 905 or contact us using our online form. We’re always happy to help you navigate the Building Regulations and ensure your project achieves compliance first time.

The post A Guide to Extractor Fan Testing appeared first on SoundTesting Services UK.

As part of the evolving UK Building Regulations, Part F (Ventilation) now mandates that all intermittent extractor fans — such as those installed in kitchens and bathrooms — must have their airflow rates tested on-site. These results must be submitted to the local Building Control Body (BCB) before the property can be signed off and handed over.

At APT Sound Testing, we specialise in helping developers, contractors, and homeowners ensure full compliance with these updated regulations. With our UKAS accreditation and expert team of consultants, we offer efficient, cost-effective extractor fan testing, often conducted at the same time as your air and acoustic testing, to save time and reduce project coordination challenges.

Why Extractor Fan Testing Is Now Essential

As energy efficiency standards tighten, new buildings are becoming increasingly airtight and insulated. While this is great for reducing heat loss, it also places more demand on mechanical ventilation systems to ensure good indoor air quality. Poor ventilation can lead to moisture buildup, damp, mould growth, and even health issues for occupants.

To address this, Approved Document F outlines strict requirements for Mechanical Ventilation and Heat Recovery (MVHR) systems, as well as intermittent extractor fans. These systems must be tested, commissioned, and certified before a building can be signed off.

This makes extractor fan testing not only a compliance requirement—but a crucial part of ensuring occupant comfort and well-being.

Types of Ventilation Systems Under Part F

Approved Document F defines four types of ventilation systems, known as Systems 1 to 4. Here’s a quick breakdown:

System 1: Background Ventilators + Intermittent Extract Fans

This is the most commonly used approach. Moisture and odours are extracted via fans in wet areas (e.g. kitchens, bathrooms), while fresh air is introduced through trickle vents or background ventilators in windows or walls.

System 2: Passive Stack Ventilation (PSV)

This uses natural airflow driven by wind and temperature differences. It includes roof-level outlets and background ventilators—ideal for energy-conscious homes but harder to control.

System 3: Continuous Mechanical Extract Ventilation (MEV)

MEV systems continuously remove air from wet rooms using mechanical fans, usually ducted to one central point. Fresh air enters via trickle vents.

System 4: Mechanical Ventilation with Heat Recovery (MVHR)

MVHR systems provide both supply and extract ventilation through ducts, while also recovering heat from the outgoing air. This is the most energy-efficient system but requires careful design and installation.

Not sure which system is right for your property? Contact our experienced team to talk through your project needs and compliance strategy.

Required Extract Rates for Domestic Fans

Approved Document F outlines the minimum airflow rates that each extractor fan must achieve, regardless of property size or type:

• Kitchens (cooker hood or similar): 30 litres per second (l/s)
• Bathrooms (intermittent fans): 15 l/s
• WCs (sanitary accommodation): 6 l/s

These rates must be verified on-site using calibrated equipment. Failure to meet the required airflow levels can delay handover and lead to additional remedial costs.

When and How We Test

In most cases, our team can carry out Ventilation Flow Rate Testing during the same visit as your Air Tightness Test. This means you can achieve Part L and Part F compliance simultaneously, saving valuable time and project costs.

Our engineers are trained to work efficiently and respectfully on active construction sites, ensuring minimal disruption and rapid turnaround of test results.

Pre-Test Checklist: Preparing for Extractor Fan Testing

To ensure a smooth testing process, the following elements should be complete before we arrive on site:

1. Electrical supply connected to all extractor fans.
2. Fans must be fully installed and operational.
3. Surrounding finishes (e.g., plasterboard/masonry) must be sealed properly to ensure airtightness.
4. All windows and external doors must be installed.
5. Trickle vents fitted to all applicable windows.
6. Safe access must be available to all test points (both internal and external).
7. SAP calculation worksheets must be provided for each unit.
8. All internal doors installed.
9. Ventilation specifications for each fan type must be supplied.
10. Floor plans and sections must be submitted at least 3 working days in advance.
11. Occupancy schedule indicating the number of residents per unit.
12. Parking space provided within 50m of the building.
13. The building envelope must be complete—doors, windows, cladding installed.
14. Interior finishes complete, including switches, sockets, flooring, and ceiling surfaces.

Need help reviewing your site readiness? We’re here to guide you through the process.

Why Choose APT Sound Testing?

APT Sound Testing are a UKAS-accredited laboratory, meaning our testing and reporting meet the highest standards of accuracy and reliability under ISO certification. With years of experience in acoustic design and building compliance, we’ve worked on thousands of projects, from single dwellings to large residential developments.

Our clients return to us time and again because we offer:

• Fast, efficient service
• Expert consultancy
• Combined testing packages (air, sound, vent)
• Reliable certification for building control
• Friendly, knowledgeable support

We understand that compliance isn’t just about ticking boxes, it’s about delivering healthier, more comfortable homes. That’s why we take the time to understand your project’s unique needs and offer tailored solutions every time.

Get in Touch Today

Our team is ready to help you meet your Extractor Fan Testing and ventilation compliance obligations with ease and confidence. Whether you’re planning a new build or preparing for completion, we’ll ensure your extractor fan systems are correctly tested, certified, and fully compliant with Approved Document F.

Call us today on 01525 303905 or use our contact form on our website to speak with one of our expert consultants about your project. We’re here to help you every step of the way.

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