Can I ask the installer to leave trickle vents off?

You can ask, and a compliant installer will say no. They are self-certifying the work against the regulations, so omitting required ventilation puts their registration at risk as well as your certificate.

Do trickle vents make the house colder?

The heat loss through them is small, and they are closeable for the coldest days, though they are intended to stay open. The condensation they prevent costs far more to put right than the heat they let out.

Do I need them if I have extractor fans?

Extract ventilation in kitchens and bathrooms and background ventilation in habitable rooms do different jobs, and one does not replace the other. Your installer will confirm what your specific rooms need.

Regulations · 03 of 11

Do new windows have to have trickle vents?

In most cases yes. Since the 2021 edition of Approved Document F, replacement windows in England generally have to provide background ventilation no worse than what they replace, and in practice that means trickle vents. An installer offering to leave them off is offering to make the work non-compliant.

Trickle vents are the single most complained-about detail on a new window. The complaints are understandable and the regulation is still the regulation.

Why the rule exists

Older houses leaked air through gaps you could not see, and that unplanned leakage carried moisture away. Modern windows seal properly, which is the point of them, and sealing a house without replacing that ventilation causes condensation, damp and mould.

Trickle vents are the cheap, always-on answer: a controllable slot that provides background ventilation whether or not anyone remembers to open a window.

What the requirement actually says

The principle is that replacement work should not make ventilation worse. If the window being replaced had background ventilators, the new one needs them, generally sized at least as large. Where the old window had none, the guidance still points firmly towards providing them.

There is nuance here, and the right person to apply it is your installer or building control, not a website. What is not in doubt is that leaving them off because the customer dislikes the look is not one of the exceptions.

Living with them

The two real objections are appearance and draughts. Both are addressable.

Appearance. Vents can go in the frame head rather than through the glass unit, and colour-matched covers are far less obtrusive than the white default on a dark frame.
Draughts. A vent that whistles or blows is usually a cheap one, or one badly sited. Better vents have acoustic and baffle options.
Noise. If you are on a busy road, ask for acoustic trickle vents specifically. A standard vent undoes some of the noise benefit of the new glazing.

Questions

Can I ask the installer to leave trickle vents off?: You can ask, and a compliant installer will say no. They are self-certifying the work against the regulations, so omitting required ventilation puts their registration at risk as well as your certificate.
Do trickle vents make the house colder?: The heat loss through them is small, and they are closeable for the coldest days, though they are intended to stay open. The condensation they prevent costs far more to put right than the heat they let out.
Do I need them if I have extractor fans?: Extract ventilation in kitchens and bathrooms and background ventilation in habitable rooms do different jobs, and one does not replace the other. Your installer will confirm what your specific rooms need.

Note This guide is general information about England and Wales, not advice about your specific property. TrustedGlazing is an introducer and does not install, survey or quote. Rely on your installer's survey and your local authority for decisions about your own home.