Replacement windows can make a home more airtight, so ventilation needs to be considered before ordering. Trickle vents are small openings, usually near the top of a window, that let outside air into a room while the window is closed. They provide background ventilation: a regular supply of air.
What is Part F?
Part F is the ventilation part of England's Building Regulations. Approved Document F gives guidance on meeting it. Other UK nations have different guidance. This article explains the general approach for homes in England; it cannot decide what a particular home needs.
Which guidance applies to your home?
For most replacement work in England before 24 March 2027, the 2021 edition of Approved Document F remains the usual starting point. The 2026 edition takes effect on 24 March 2027 for most work and on 24 September 2027 for higher-risk building work, subject to the official transitional arrangements. Ask your installer or building control body which version applies before agreeing the windows and ventilation.
Do replacement windows need vents?
Where the old windows have background vents, the replacements generally need suitable vents at least equivalent to them. Where the old windows do not have vents, the existing ventilation still needs to be considered; leaving the new windows without vents is not automatically acceptable. A suitable alternative arrangement may be possible.
Can a wall vent be an alternative?
An appropriate wall ventilator can provide background ventilation. An existing one can sometimes mean no extra window vent is needed. An air vent serving a fire or appliance has a different purpose and should not simply be counted as room ventilation.
Discuss ventilation before ordering
Tell us about existing window or wall vents, extractor fans and any whole-home ventilation system. Mention noise concerns and visible moisture. We can discuss the appearance and position of vents, but the final arrangement must meet the requirements for the home.
Questions
Can I refuse vents and sign a disclaimer?
Signing a form does not remove the ventilation requirements. Discuss a suitable alternative before ordering.
Can I leave a window on its night latch instead?
No. The government guidance does not accept a window locked slightly open as suitable background ventilation.
Does this guide tell me what my house needs?
No. It explains general guidance. The building, ventilation system and applicable requirements must be considered for the actual work.
Send photos, approximate measurements and pictures of any existing vents. We can discuss the window and ventilation specification before the final survey.
