What Are Trickle Vents?
Trickle vents are small openings, usually integrated into window frames, that allow a controlled amount of fresh air to enter a building. They help to ventilate spaces even when windows are closed, reducing the buildup of moisture and indoor pollutants.
Why Are Vents Important?
- Improved Ventilation – Vents facilitate continuous air circulation, reducing stale air and preventing indoor pollutants from accumulating.
- Condensation Prevention – By allowing airflow, this helps to minimise condensation, which can lead to mould growth and damp issues.
- Compliance with Building Regulations – In many cases, building regulations require adequate ventilation in homes. New building codes often mandate the inclusion of trickle vents in replacement windows.
- Security and Energy Efficiency – Trickle vents provide ventilation without the need to open windows, maintaining security and reducing heat loss compared to leaving a window ajar.
Are Vents Mandatory?
Building regulations in the UK and many other regions require trickle vents in certain situations. If you are replacing windows in a property with existing trickle vents, you must retain them or provide an alternative ventilation solution. New-build homes also often require adequate background ventilation, which trickle vents provide.
Do Trickle Vents Cause Heat Loss?
A common concern about trickle vents is that they may contribute to heat loss. While they do allow a small amount of air exchange, modern designs are engineered to minimize drafts and retain as much heat as possible. Proper insulation and controlled ventilation balance comfort with air quality.
Approved Document F: Trickle Vents
How would an installer know how many trickle vents to install per window?
It’s the room type that sets out the size of background ventilation required. A habitable room such as a lounge, for example, requires in most instances 8000mm² (Equivalent Area). This could be made up of 4 x 2000mm² or 2 x 4000mm² or any other combination.
Would the installer be responsible for designing the window to suit the amount of trickle vents required?
The installer is the competent person and should be designing the window to achieve building regulation compliance where feasible.
If air bricks are in the property, would trickle vents be required?
Alternative ventilation types can be utilised if they can satisfy a BCB (building Control Body) that they are suitable. With “Air Bricks” these would need to provide the correct amount of ventilation and be controllable. Cavity or under floor vents are not background ventilation.
If ventilation fans are installed, would trickle vents be required?
If continuous mechanical ventilation is installed, then those rooms do not require vents but all habitable rooms will require 4000mm² vents to be installed.
If night locking vents are on the windows, would trickle vents still be required?
Yes. Two stage locking handles or night vents are not acceptable, as they are less secure and the equivalent area cannot be accurately measured.
What would the installer do if a customer refuses completely to have trickle vents installed on their windows?
It is up to the competent installer to adhere to the Building Regulations.
Do commercial buildings require trickle vents?
Approved Document F1 is only applicable to dwellings. Approved Document F2 covers all buildings other than dwellings. This does require background ventilation to be installed when replacing windows, but with different size and location requirements.
Are trickle vents required on all doors being installed?
Background ventilation is assessed per room, not per window or door. There may be instances where background vents should be installed in doors. For example, a room that is only opening to the outside, is a door such as a set of French doors in a lounge. Hallways on the other hand, are not habitable rooms and therefore a door in hall would not require background ventilation.
If a window is too narrow for a trickle vent, is it exempt?
If you cannot install the required amount of ventilation in a window, then you should install whatever is feasible.
If a window is fixed and the plaster line is too low to clear a trickle vent, would knock on have to be used to make a trickle vent fit?
This would be a possible solution. A larger frame section may be another possibility or an over glass ventilator.
If a customer has allergies/medical reasons such as chronic hayfever etc, would this be grounds to not fit a trickle vent?
No, background ventilators must be controllable so could be closed at times of high pollen etc. to mitigate the issue.
Are there any exceptions to trickle vents being installed?
Listed buildings and sometimes conservation areas are exempt.
If decibel glass is required, are trickle vents going to be installed?
If sound is an issue, then a noise attenuating background ventilator should be fitted.
How as an installer are we supposed to explain that the new energy efficient windows that they’re having installed have to have holes in them?
Building Regulations require that the ventilation in your home is not made worse by installing energy efficiency measures. When work is done to homes, gaps and cracks are often sealed up.
These gaps and cracks were providing ventilation and in older homes may have been the only source of ventilation.
Professional Window Installation
FENSA’s mission is to improve window and door replacements across England and Wales, by professionalising installers and protecting homeowners. FENSA makes sure the work complies with building regulations, is energy efficient, and registered with the local council. And verify that every FENSA Approved Installer’s guarantee is insured. We are fully accredited by a range of third parties including FENSA and PWF. We are FENSA approved window and door installers. To
Contact us at DW Windows, a trusted provider of windows, doors, and home improvements in the West Midlands, to explore our range of modern doors and enhance the security of your home today and start your free quote.
Read this FREE FENSA guide for updated building regulations – including trickle vents!
Working closely with #TeamDW Jess is helping homeowners in Wolverhampton, Dudley and the majority of the West Midlands improve their properties with a range of windows, doors and extensions with friendly budgets in mind, ensuring the best customer experience.
- Do I Need Trickle Vents On My Windows? - March 18, 2025
- Popular Home Renovation Trends For 2025 - February 3, 2025
- Standard Window Sizes in the UK - January 14, 2025
Back to Top