Key Summary
UK Building Regulations require adequate bathroom ventilation, especially in new builds.
Bathrooms without a window must have an extractor fan by law.
Even in older homes with windows, a fan is highly recommended to prevent mould.
Poor ventilation can lead to condensation, damp, and structural damage.
Extractor fans should be installed by a qualified electrician to meet Part P compliance.
Choosing the right fan type ensures effective moisture control and quieter operation.
In the UK, bathrooms must have proper ventilation, and in most modern homes, that means an extractor fan. While a window might be enough in some older properties, newer builds are held to stricter standards. Without good ventilation, moisture builds up fast, leading to damp, mould, and costly damage. So, do you really need an extractor fan in your bathroom? Let’s break down what the rules say- and why it matters.
Do I Need an Extractor Fan in a Bathroom?
Bathrooms with a Window
Under UK Building Regulations (Approved Document F), bathrooms require “adequate means of ventilation.” If your bathroom has a window that opens directly to the outside, it may be considered sufficient in older homes, particularly those built before 2006. However, natural ventilation (like opening a window) is increasingly seen as inadequate for moisture-heavy environments, especially during colder months when people avoid opening windows.
Our recommendation: Even if your bathroom is in an older property with a window, we still strongly advise installing an extractor fan to reduce moisture, prevent mould, and protect your home long-term.
Bathrooms without a Window
If your bathroom does not have a window, then yes, you absolutely need an extractor fan. It’s a legal requirement. Mechanical ventilation must be installed, typically in the form of an extractor fan ducted to the outside.
Building regulations state that bathrooms without openable windows must have continuous or intermittent mechanical extraction that meets specific performance criteria (see below).
New Builds and Extensions
If you’re building a new home or adding an extension, Approved Document F applies fully. This means:
Intermittent extract fans must be capable of extracting 15 litres per second in bathrooms (or 30 l/s if installed over a bath or shower in certain layouts).
Or you can use continuous extraction systems at lower flow rates.
All extractor fans must vent outside, not into lofts or cavities.
Our recommendation: Simply installing a fan isn’t enough. You must also consider backdraught shutters, ducting quality, and fan position.
Shower Rooms or Ensuites
For smaller bathrooms, en-suites or shower rooms, the rules are the same. The key factor is the moisture and humidity created by use. Even short showers can generate significant levels of water vapour, leading to condensation without adequate extraction.
Why Bathroom Ventilation Is Important
Without proper ventilation, your bathroom becomes a breeding ground for moisture-related issues. Extractor fans are a vital part of bathroom moisture control, helping protect your property and improve comfort.
Preventing Mould and Mildew
Warm, damp air allows mould spores to flourish. Mould not only looks unsightly but can also cause respiratory issues and allergies. It often accumulates around tile grout, ceilings, and window frames- and once established, it’s difficult to remove completely.
Avoiding Condensation and Damp
Hot showers release litres of moisture into the air. Without extraction, this condenses on cold surfaces like mirrors, windows, and walls. Over time, this leads to peeling paint, swollen wood, and structural issues.
Protecting Walls, Paintwork, and Fixtures
Bathrooms are full of vulnerable finishes- think MDF vanity units, painted plasterboard, wooden trims, and metal fittings. Constant exposure to moisture without ventilation can degrade these materials quickly, reducing your bathroom’s lifespan.
Improving Indoor Air Quality and Reducing Odours
Extractor fans also remove odours, airborne chemicals from cleaning products, and volatile organic compounds (VOCs). This creates a healthier and more pleasant environment for everyone using the space.
Types of Bathroom Extractor Fans
Choosing the right extractor fan depends on your layout, bathroom zone, and usage habits. Here’s a breakdown of common types:
Axial Fans
Best for wall or window mounting.
Suitable for bathrooms with short duct runs (under 1.5m).
Typically quieter but less powerful.
Common in smaller bathrooms or where the fan is mounted directly through an external wall.
Centrifugal Fans
Designed for longer duct runs, often used in flats or internal bathrooms.
More powerful than axial fans, capable of pushing air through several metres of ducting.
Slightly noisier but necessary in many retrofit situations.
Inline Fans
Installed within the loft or ceiling void, not visible inside the bathroom.
Air is extracted via ducting to an external grille.
Ideal for bathrooms without windows or where a discreet fan is preferred.
Can be combined with silent motors for low-noise performance.
Humidity or PIR-Activated Fans
Humidity-controlled fans activate when humidity rises above a set level (usually 60–70% RH).
PIR (Passive Infrared) models turn on when someone enters the room.
Both are excellent for hands-free control and energy efficiency.
Popular in bathrooms used by children or guests.
Tip: Look for IP-rated fans (minimum IP44) when installing near a shower or bath. A silent extractor fan for bathrooms is also worth considering for improved comfort.
Do I Need Planning Permission or an Electrician?
Planning Permission
In most cases, you don’t need planning permission to install an extractor fan in your bathroom- especially if it’s part of a renovation or upgrade. However, if your property is listed or in a conservation area, special permission may be required.
Electrical Requirements and Part P Notification
Installing a bathroom extractor fan falls under notifiable work according to Part P of the Building Regulations. This means it must be carried out by a competent, qualified electrician registered with a scheme like NICEIC or NAPIT.
Unsure what to expect with electrical work in your bathroom?
Read our guide to electrical safety checks in the UK
After installation, the work must be certified, and you should receive a Part P Building Regulations Compliance Certificate.
Frequently Asked Questions
Can I have a bathroom without an extractor fan?
If the bathroom has a window and the property is old, it may be acceptable without one. However, newer properties and any bathrooms without windows must have an extractor fan by law.
What size extractor fan do I need for a bathroom?
Extractor fans are rated in litres per second (l/s) or cubic metres per hour (m³/h). For standard bathrooms:
15 l/s is the minimum intermittent extraction rate required under building regs for bathroom extractor fans.
Larger or heavily used bathrooms may benefit from higher flow rates or continuous extraction.
How long should a bathroom fan run after a shower?
Most modern extractor fans have a run-on timer set between 15 to 30 minutes. This helps remove residual humidity after you leave the room.
Do extractor fans remove all moisture?
Extractor fans dramatically reduce humidity, but they may not remove 100% of moisture, especially if undersized or poorly installed. Using them in combination with other ventilation methods, like opening a window, offers the best result.
Can I install an extractor fan myself?
Only if you are a qualified electrician. DIY installation is not recommended because it involves working with electrics in a wet environment, and must comply with IP ratings, zoning, and building regulations. Improper installation may void your home insurance or fail a survey.
How to ventilate a bathroom without a window?
Use a powerful extractor fan connected to ducting that vents externally. Options include inline fans with a ceiling vent, or centrifugal fans installed in the ceiling or wall. Pair with humidity control features for best performance.
Conclusion
Extractor fans aren’t just a luxury- they’re essential for safe, compliant bathroom ventilation in the UK. Whether you’re renovating or building from scratch, proper extraction helps prevent mould, protects your home, and keeps your air fresh.
If you’ve been asking, “do I need an extractor fan in my bathroom?”, the answer is almost always yes.
Don’t risk damp, damage or non-compliance- get professional advice and install the right fan for your space. Contact us today.