When buying new doors or windows, many homeowners are unsure whether they need trickle vents. With changes to building regulations and a range of product options on the market, understanding when trickle vents are required is essential. This guide explains what trickle vents do, when they’re legally needed, and how to choose the right specification for your home.

What is a trickle vent?

A trickle vent is a small, controllable ventilation slot built into the frame or sash of a window or door. It allows a consistent flow of background air into the property without needing to open the window.

Trickle vents help improve indoor air quality, reduce condensation and provide continuous ventilation as required under Building Regulations.

What do trickle vents do?

Trickle vents:

• Provide background ventilation

• Help prevent condensation and mould

• Reduce moisture build-up in kitchens, bathrooms and bedrooms

• Improve airflow without compromising security

• Allow ventilation even when windows are closed

They are designed to meet Part F (Ventilation) requirements.

When are trickle vents required?

1. If you are replacing existing windows that already have vents

You must include trickle vents in the new windows. This keeps the property compliant with current regulations.

2. If your home relies on background ventilation

Most modern homes require a minimum level of continuous airflow. Trickle vents provide this without relying on extraction systems.

3. If you have high-performance insulation or airtight construction

New builds and renovated homes often create airtight rooms. Trickle vents help prevent moisture build-up and stale air.

When trickle vents may not be required

You may not need trickle vents if:

• Your home has a fully functioning mechanical ventilation system

• You are replacing windows that never had vents, and no other part of the property relies on them

• A ventilation strategy is already in place (e.g. whole-house MVHR)

However, your installer or building control officer may still recommend them depending on the room type.

Do trickle vents affect heat loss?

Modern trickle vents are developed to meet strict standards.
They provide controlled airflow without causing draughts or significant heat loss.

Many systems now include:

• Acoustic vents for noise reduction

• Secure night-vent settings

• Insulated vent profiles

• Slimline designs that sit neatly within the frame

Should you choose trickle vents for new doors?

For large glazed doors — such as bifolds, sliding doors or French doors — trickle vents are sometimes required depending on the ventilation balance of the room.

If the room has:

• No other windows

• High moisture levels

• Limited airflow

Then trickle vents in the door frame or an alternative ventilation strategy may be needed.

What if I don’t want trickle vents for aesthetic reasons?

Many homeowners prefer cleaner sightlines without vents. If so:

• Check whether the existing windows had vents

• Review the ventilation strategy for the room

• Consider alternative solutions (MVHR, boosted extraction, window restrictors)

If trickle vents are legally required, they must be included.

How to choose the right trickle vents

Look for:

• Ventilation that meets Part F compliance

• Acoustic performance if you live in a noisy area

• Slimline or colour-matched vents for a cleaner finish

• Frame-integrated vents where possible

Our systems offer discreet, colour-matched options that blend with the frame for minimal visual impact.

Not sure if you need trickle vents?

If you’re unsure whether your installation needs trickle vents, our team can advise based on your property, existing windows and compliance requirements. We’ll help you choose the correct specification so your installation meets regulations and performs as it should.