Can a bathroom be ventilated without installing a visible fan on the window or inside the ceiling?
Yes, the exhaust fan can be placed on the roof and connected to the bathroom through an air duct, so that an extraction grille that matches the finish remains inside the bathroom. In this way, the fan is moved to a remote location while continuing to extract air and discharge it outside.
In this article, we explain the concept of the system and the main considerations that help implement it correctly.
How does a rooftop bathroom exhaust fan work?
Air movement begins at the extraction grille inside the bathroom, then passes through the air duct to the external fan, which discharges it outside the building.
The solution shown in the episode consists of a rooftop exhaust fan, a mounting base, and an air duct connected to an internal grille integrated with the ceiling design.
It is important that the exhaust air reaches the outside of the building and that the path is implemented in full; concealing the extraction grille alone does not achieve the required ventilation.
What is the benefit of placing the fan away from the bathroom?
Remote fans move the noise source of the motor away from the user, while keeping the extraction grille within the space. Manufacturers explain that this arrangement helps reduce noise inside the bathroom.
It also gives greater flexibility in coordinating the grille with the ceiling and décor, and can make the fan easier to access for maintenance if its rooftop location is equipped and safe.
However, the final noise level also depends on the choice of fan, the air velocity, the mounting method, and the design of the air duct and grille.
Can the extraction grille be concealed with the lighting?
The episode shows an example of a built-in extraction grille inside a ceiling recess, close to the lighting, to reduce its visibility from inside the bathroom.
Similar solutions can be studied through coordination between the ventilation engineer and the interior designer, provided there is sufficient extraction area, a clear air path, and the ability to clean the grille.
It is also necessary to separate ventilation requirements from electrical fittings, and to select lighting units suitable for the location.
The success of the concept depends on air passing at the required rate, together with the grille’s shape matching the finish.
How do you select the fan and the air duct diameter?
Selecting the fan based on the connection diameter alone is not sufficient. The design requires determining the required airflow, then calculating the resistance of its path.
The pressure the fan must overcome is affected by the length of the air duct, the air velocity within it, and the number of bends and elements that obstruct the flow.
Therefore, the pipe size seen in one project is not a fixed size for all bathrooms. The fan, the duct and the grille must be selected together according to the requirements of each case.
Does each bathroom need its own fan?
In the project shown in the episode, a separate fan was dedicated to each bathroom, allowing each one to be operated independently.
There are also solutions that use one remote fan to serve more than one extraction point. The appropriate choice is determined by the distribution of bathrooms, the operating requirements and the network design.
When using a shared network, the airflow distribution must be studied, and the transfer of air and odors between spaces must be prevented.
Important details before closing the ceiling
To achieve adequate performance, review the following:
- The airflow extracted from each bathroom.
- Providing a suitable path for make-up air to enter.
- Sealing the duct joints and avoiding compression of flexible sections.
- Fixing the fan and addressing vibration transmission.
- Protecting roof penetration details from water leakage.
- Selecting a discharge location away from air intakes and windows, as per the design.
- Providing access for maintenance and cleaning.
After implementation, extraction is tested at the internal grille, since the fan spinning alone is not sufficient to prove that the system performs its function.
Frequently asked questions
Does this solution replace the exhaust fan?
The fan is still present, but it is installed in a remote location instead of inside the bathroom.
Does the system become silent?
It can help reduce noise, but the noise level depends on the design, the equipment and the quality of installation.
Can it be implemented after finishing works?
That depends on the availability of an air duct route, the space above the ceiling, and access to the discharge location. Early planning provides wider options.