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Written by Rob Lancaster

Trickle Vents – What are they and why do you need them? A Buyer’s Guide

Window trickle vents

On many modern properties, trickle vents for UPVC doors and windows are commonplace – but what are they? If you live in the UK, you’ll probably be familiar with the small, hooded vent often found above UPVC doors and windows. This is a trickle vent or window trickle vent, and is important to your property in more ways than one. In this article, we’ll discuss why you need them, how to change a trickle vent, and the best trickle vent products.

Background ventilation

Even in winter, it’s not uncommon for a house to get too warm. The heating is on, everyone is intent on staying indoors, and plenty of hot showers and hot meals are had. But if it’s too hot, you don’t want top to be opening a window to let too much cold air in. This is where the trickle vent comes in. A trickle vent is a slim, unobtrusive vent that allows the free movement of fresh air from outside to inside, and vice versa.

UPVC doors and windows

These vents are often found on UPVC doors and windows but can also be found on other manufacture materials. By allowing the movement of fresh air in and out of the property, a trickle vent negates the need to open the window most of the time. The plastic hood that covers the vent can be flipped open or shut depending on your preference or the temperature of your home, so if it gets too cold you can keep hold of your warm air and maintain that cosy temperature.

Building regulation

Trickle vents and window trickle vents have become mandatory in building regulation, and so expect to see them on most modern properties. They are necessary because of the ventilation they provide to houses. As building practices have become more advanced, properties have become increasingly airtight. The trickle vent was made mandatory to maintain the flow of fresh air in our increasingly energy efficient houses. Without them, all sorts of issues can occur.

Trickle vents vs air bricks

Before trickle vents were introduced, air bricks were used. You may have seen an air brick without even realising what it was! Have you ever seen a brick on the side of a house with several holes in it, often located above doors or windows? This is an air brick, and used to serve the same purpose as a trickle vent does today – to allow the movement of fresh air into a property. The added bonus of a trickle vent, however, is that you can close them if you want to, which never used to be the case with an air brick.

Fresh air

Trickle vents are used to prevent condensation on your windows and in your property by allowing a cool flow of fresh air from the outside. They can help to prevent odour build up, and can also help to regulate moisture, which can prevent mould from forming. They are especially important in kitchens and bathrooms, which are often the wettest part of a property. Trickle vents won’t provide a noticeable draft, just a pleasant, fresh flow of air, and won’t allow too much noise into your property either, unlike the old-fashioned air brick.

Installing or replacing a trickle vent

If you already have window trickle vents, then replacing them should not be too much of an issue: most will only require a few screws to be removed before replacing, and some are even clip fit – just like our popular Clip Fit F Vent from Greenwood. You can simply remove the old vent and add your new one in. Most modern vents are incredibly slim and look very tidy when installed. If your property does not already have windows and doors fitted with trickle vents, then installation can be slightly more difficult. Installing a trickle vent from scratch will involve measuring and drilling through your door or window frame, which may not be appealing to some people. Many trained labourers will be able to do the job quickly and professionally, however, so getting trickle vents fitted to your home should be a breeze.

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About the author

Rob Lancaster is part of the marketing department at He researches and writes content for the site, producing guides, blogs, and articles.

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