What is a trickle vent?

Designed to be a functional part of a window that lets air circulate through your home, according to Building Regulations, trickle vents come highly recommended. Unfortunately, there’s no hiding the fact that they can look unsightly. We explain what trickle vents are, why you need them, and how to choose products with a discreet design.

Modern day windows are exceptionally high performing when it comes to retaining heat, which is great for reducing energy consumption and makes your home feel warm and cosy.

Nevertheless, modern windows don’t do a great job when it comes to ventilation. It’s a requirement that every room in a house should have adequate ventilation, otherwise internal pollutants like smoke, cooking smells, irritants, and allergens can hang about and have an impact on the quality of air in your home.

Completely airtight, sealed windows can also cause problems with moisture, condensation, and mould. Ironically, the rattling, leaking, poorly fitted windows of days gone by would let plenty of air in!  

When it comes to buildings, there are three different types of ventilation:

‘Purge’ ventilation is achieved by simply opening a window and letting in lots of fresh air into your home.

‘Extraction’ ventilation is ideal for rooms like kitchens or bathrooms regularly exposed to cooking smells or moisture.

‘Background’ ventilation is described as “small ventilation openings designed to provide controllable whole-building ventilation”. The most common way to create background ventilation is with trickle vents.

What are trickle vents?

Trickle vents are small openings in a window that allow a tiny amount of air to pass through, securely and constantly drawing out stale air and bringing in fresh air from outside.

As they are so small, they don’t ruin the thermal efficiency of glazed windows and do not compromise on the security of your home as an open window might do. Trickle vents are positioned through the head of the frame, but on some occasions, this is not possible so they can sometimes be routed over the top of the frame or into the glazed area along the top of the glass unit. Whether a window is made from PVC-u, timber, steel or aluminium, they can be fitted with a trickle vent.

Background ventilation should ideally be positioned 1.7m above floor level so that any draughts that do come through won’t be felt, and trickle vents are ideal for meeting this requirement. Trickle vents can be opened by hand, or by cords and rods if the window is positioned up high.

Do you need trickle vents?

Building Regulations in England and Wales state that a home requires adequate ventilation. The general rule was always to replace windows with like for like. Therefore, if you’re replacing a window with a trickle vent then you would need to make sure the new windows have a similar sized vent in order to maintain the same level of ventilation.

Guidelines are provided for both habitable rooms and wet rooms/kitchens if it is not possible to identify the existing vent’s capacity performance.

In 2006, the Building Regulations changed to stipulate that all new windows should include trickle vents, but many window manufacturers were unhappy with this decision. After further discussions, the regulations were changed and now trickle vents are advisable, rather than a requirement. For all new-build projects, including extensions, background ventilation is mandatory. Although installing trickle vents in your windows is the most popular solution, you can also consider air bricks as an alternative.

Overall, there are many different factors that will determine the levels of ventilation levels required in a property, but a reputable and certified window installer will be able to advise you on the correct products, and will also display the EA (Equivalent Area; the industry accepted method for determining the performance of a ventilator) of their products.

Discreet design for a beautiful finish

So why did so many window manufacturers express their dismay when the building regulations changed and declared that all windows needed to have trickle vents as a requirement? Quite simply, they can ruin the aesthetics of a beautifully designed window and they just don’t look as nice.

Even though the regulations were changed back to their original recommendations, there are still many benefits to trickle vents and we still see a demand for them. New and cleverly designed trickle vents have been developed so that they don’t compromise on the style of the window, but unfortunately there are still some rather unsightly products on the market. Some manufacturers will make windows with ugly vents fitted in the sliding sash, or have a very visible plastic canopy stuck out of the opening casement or head of the frame.

For an elegant window, opt for premium products that have been developed to incorporate discreet trickle vents that are hard to see. These timber sash windows have concealed trickle vents in the head frame, making them invisible from the outside and as discreet as possible from the inside. If you’re looking for a casement window with trickle vents, these have an external grille covered by a head drip made from Accoya, which is a highly durable and environmentally friendly timber.