How to Vent A Bathroom Fan Through the Roof?

How to Vent A Bathroom Fan Through the Roof?

Everyday activities that you complete in your bathroom, from washing your hands to showering or taking a nice long soak in the bath result in a large amount of moisture entering the air in the form of condensation. Over time, this excess moisture can cause common issues like mould growth, peeling of paintwork, and even structural damage in your home.

The most effective way to remove condensation from your bathroom is to install a bathroom extractor fan. These work through an electric motor that rotates, forcing air to circulate through the bathroom. This pulls fresh cold air into the room to replace and expel the warm moisture-carrying air.

Bathroom extractor fans can be connected to either a roof tile vent or installed directly into walls, to provide ventilation of this warm air to the outside of a property.

Commonly favoured due to; decreasing the possibility of backdrafts, improving airflow efficiency as hot air rises and requiring less structural alterations to your property, roof tile vents offer an effective and simple-to-fit ventilation solution.

To help you out, in this Beddoes Products guide, we walk you through how you can install a bathroom extractor fan through the roof.


Understanding Your Bathroom Ventilation Needs

Before you install your bathroom extractor fan, you first need to choose the right bathroom extractor fan, roof tile vent and location for installation. If you have already done this, you can Skip to Our Step-By-Step Guide to Venting a Bathroom Fan Through a Roof Tile Vent.


How to Choose a Bathroom Extractor Fan?

There are two types of bathroom extractor fans available in the UK: Vented Extractor Fans and Recirculating Extractor Fans. The Vented Extractor fan is what you will need to vent the air in your bathroom through a roof tile vent. These are much more effective than recirculation extractor fans as they remove the steam and condensation from the bathroom space, rather than recycling it back throughout the bathroom as recirculating extractor fans do.

Now that you know you need a vented extractor fan, you can begin comparing product models. In the UK, there are hundreds, if not thousands, of vented extractor fans available online or in hardware, plumbing and building supply stores.

These vary in cost, power (CFM - see below), IP Rating (see below), style and energy efficiency. We recommend doing your own research and speaking with in-store experts or reading customer reviews to assist you in buying the right extractor fan for your bathroom.


What is a CFM Rating?

All bathroom extractor fans come with a rating of how much air they can circulate called Cubic Feet Per Minute (CFM). The standard rule of thumb is that you will require an extractor fan with at least 1 CFM per square foot of space in your bathroom.

To calculate the square footage of your bathroom simply multiply the length by the width. For example, if the size of your bathroom is eight feet long and seven feet wide, the square footage will be 56 (8 x 7). This means that when looking for the best extractor fan to buy, you will need a fan with a rating of at least 56 CFM.


Where is it best to install a bathroom extractor fan?

The best location for your extractor fan is dependent on the layout of your bathroom and, more importantly, electrical safety and legal regulations.

Ideally, you want your extractor fan to be positioned as close as possible to the main source of steam in your bathroom. This way it can immediately extract the steam from the bathroom, minimising its opportunity to condense on any surface.

However, to adhere to building regulations and electrical safety requirements, you must identify which ‘zone’ you are trying to install your bathroom extractor fan.


What are the Bathroom Zones in the UK?

All bathrooms and wet rooms in the United Kingdom are divided into zones when it comes to installing an extractor fan and any electronic devices. These zones are known by different names but have the same specifications. For simplicity, at Beddoes Products, we will name these Zone 0, Zone 1 and Zone 2. All of the zones are measured in cuboids, with no zone areas overlapping.

Each zone has different levels of risk when it comes to electronics being exposed to water, with the lower the number, the higher the likelihood of exposure. Due to this increased probability, the electrical device (in our case the extractor fan) requires a higher IP (Ingress Potential) rating.

Bathroom Zone 0 is the area within a bath or shower cubicle up to 2.25 meters high.

Bathroom Zone 1 is a 60cm encasement of Zone 0 in all directions.

Bathroom Zone 2 is the entirety of the bathroom that is not included in Zone 0 or Zone 1.


Which bathroom zone is best for installing an extractor fan?

The ideal location to install an extractor fan is in zone 1 as it is directly above where the steam is being produced allowing it to be efficiently extracted without a chance to come into contact with, and condense on, any surfaces.

To install a bathroom extractor fan in zone 1, the fan must either be low voltage or IP-Rated to IP45. This is in line with the IEE Wiring Regulations BS7671, Requirements for Electrical Installations Section 601.

Our recommendation is to find an extractor fan with an IP45 rating as it makes the installation process much simpler and requires less electrical work.

To install a low-voltage fan, you will also need to install a step-down transformer to feed the 12-volt fan. This transformer will ensure that the fan works at a safe voltage in cases where there is any water ingress.

To adhere to the previously stated regulations, the step-down transformer is required to be installed in Zone 2 or externally. They can be installed in the wall, or more commonly when installing an extractor vent through the roof within the ceiling.


Guide to Venting a Bathroom Extractor Fan Through The Roof

Now that you have picked an extractor fan and decided on its location for installation in your bathroom, it is time to get started on venting your bathroom through the roof.

Below is a list of tools that you will require to follow our installation guide:

Ladder (if working at height)
Safety Goggles
Dust Mask
Tape Measure
Marker Pen
Utility Knife
1 Roof Tile Vent
1 Vented Extractor Fan
Electric Saw (Circular or Jigsaw)
Electric Drill
Foil Duct Tape


Installing Your Extractor Fan

An extractor fan is divided into two parts. The housing section and the grill. The housing section will be what is installed above your bathroom ceiling, with the grill being installed into the housing section on the internal side of your bathroom’s ceiling.

As previously mentioned, you want your extractor fan to be close to the main sources of steam in your bathroom and have an open loft space between two joists to install the housing section.

After carefully selecting where you are going to position your extractor fan, you then need to ensure that you can fit the housing section in your loft space (to do this you may have to use a utility knife and dust mask to remove insulation).

Next, use the power drill to make a single hole in the bathroom ceiling. This hole will be the guide for the corner of the square or circle you are going to remove. Depending on the size of your extractor fan, and the manufacturer's guidance, carefully mark out the hole you will need to create.

Wearing your dust mask, safety goggles, and gloves, use your electric saw to carefully remove the circle or square required. It is important to do this with great care to make sure there is no damage caused to the surrounding ceiling and any joists.

Once you have created the hole, connect the housing section and grill together on either side of the bathroom ceiling using the screws provided. Next, double-check that you have a close enough power source and enough flexi pipe to reach the roof tile vent.


Installing the Roof Tile Vent

If your property does not already have roof tile vents, you can read our full guide on How To Install A Roof Tile Vent (Coming Soon).

Connecting Your Extractor Fan To Your Roof Tile Vent

The final stage includes connecting all of the parts. Simply attach the pipe that was provided with your extractor fan to the top of the housing on the extractor fan (using an adaptor if necessary).

Then extend the pipe until it meets the roof tile vent connection point. The piping should be as straight as possible, but with a little slackness, to directly expel the steam produced from your bathroom to the exterior of your property.

Finally, check that the extractor fan is working by connecting it to the power supply and switching it on.


Do you need a contractor to vent a bathroom?

Venting a bathroom extractor fan through the roof can require both electrical expertise and DIY skills.

We recommend that any work that includes wiring work, especially in your bathroom, is carried out by a professional electrician. For the installation of a roof tile vent, or any major roofing work, we also recommend using a professional roofing contractor.

This guide by Beddoes Products has been created to provide educational advice and we take no legal liability for any works you undertake.

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