Trickle Vents: Ventilation for Windows

Installed as part of the window unit, trickle ventilators can provide constant, unobtrusive and secure background ventilation for a home.

trickle ventilator window frame

The importance of background ventilation

In recent years, a drive to provide thermal comfort and increase energy efficiency has seen residential dwellings becoming better sealed than ever before.

However as homes are made more airtight, internal pollutants can have a greater impact on indoor air quality. If these pollutants cannot escape, the health of those living in a home may be at risk.

Effective background ventilation is necessary to provide a healthy and comfortable internal environment for the occupants of a home.

Trickle ventilators

Trickle ventilators (or trickle vents) provide this effective background ventilation for a home, contributing to a healthy living environment by enabling unobtrusive and controllable whole-room ventilation.

They are situated at the top of windows and can be easily adjusted through the use of cords, rods or simply by hand.

The benefits of installing trickle ventilators:

Cleaner air for your home

Providing for effective background ventilation in your home may help to reduce the severity of health problems such as those brought on by respiratory ailments like asthma. It can also help to manage background air levels of pollutants such as carbon monoxide and carbon dioxide in your home.


Trickle ventilators allow constant ventilation while a windows is closed and/or locked, and their installation footprint does not enable intrusion into a property.

24-hour operation

Even at night and while you are away on holiday, trickle ventilators can still operate to provide background ventilation to your home.

Noise reduction

Trickle ventilators provide ventilation without the need to open windows, reducing noise levels as a consequence. In noisier locations, such as near a busy road or an airport, acoustic options are also available.

Condensation reduction

Some homes may have an existing problem with condensation, especially in colder weather. Fitting windows with suitable trickle ventilation may improve the condensation problem, and could potentially reduce consequent mould growth and internal surface damage.

Cost effective

Trickle ventilators represent the lowest cost route for provision of background ventilation without the need for air bricks and incur no ongoing electricity costs.

Are trickle ventilators mandatory?

When replacing a window, installing a trickle ventilator is not mandatory unless the existing window has one. If it does, the new trickle ventilator must offer at least the same performance as the existing vent.

However even if the existing window doesn’t have a trickle ventilator, it is recommended to consider installing one when replacing it.

Trickle vent designs

Trickle ventilators can be fitted with all window framing materials including PVC-u, timber, steel and aluminium.

Through frame design


A through frame trickle vent design is often positioned through the top of the frame. The trickle vent is integrated into the frame itself.

Over frame design
window trickle vent over frame design

An over the frame design is used when it is not possible to fit the trickle vent through the frame. The trickle vent makes provision for the ventilation to be routed over the frame or head of the window.

Glazed in
window trickle vent glazed in

The trickle vent is fitted into the glazed area along the top of the sealed glass.

For more advice and information about ventilation in your home, get in touch with a local GGF Member company.

Related topics

– A guide to home ventilation
What is condensation and why does it occur on windows?
Window condensation – where the water vapour comes from
Where condensation can form on a window and how to reduce it
Top tips on reducing condensation room by room