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Ventilation

Please note: Any installations must adhere to the relevant regulations in place at the time of install. These regulations are subject to change.

What is Ventilation?

Why is it Important? Ventilation is the exchange of fresh air from the outside and stale air and moisture from the inside of a property.

Current building regulations and legislation require adequate ventilation to be installed in specific circumstances, such as:

• When insulation is being installed – Insulation makes your home more ‘air-tight’, reducing natural airflow. What qualifies as adequate will depend on your property.

• When damp or mould issues have been identified – These issues can indicate that there is not enough airflow to remove moisture from the air.

Common Misconceptions / FAQs

Do I have to have ventilation?

Yes. Building regulations require correct ventilation. Without it, you risk:

• Poor internal air quality (IAQ)

• Increased moisture

• Condensation and mould

In case of a gas or carbon monoxide leak, vents could save your life.

Won’t it cause condensation in my house?

No. Adequate ventilation removes excess moisture before it can condense inside your home.

Won’t it make my house colder?

Ventilation is about balance. Keep:

• Wall temperatures (especially external) above 16–17°C

• Room temperature around 21°C

• Showering, bathing, and cooking produce moisture. Use extractor fans or open a window after these activities—even in winter—to let moisture escape.

Types of Ventilation

There are two types of ventilation:

1. Uncontrolled (Natural) Ventilation

Cannot be turned on or off.

Includes drafts around ill-fitting windows, doors, gaps in floors, etc.

2. Controlled Ventilation

Can be used to regulate the amount of airflow through the property.

Your property’s current ventilation/airflow can be impacted by features such as:

• Chimneys (blocked/unblocked)

• Flues

• Wall or floor type

• Existing ventilation (e.g., extraction fans)

Too much ventilation causes high heat loss and uncomfortable temperatures, while too little can lead to damp and mould.

Adequate Ventilation is Necessary to:

• Maintain ‘fresh’ air to breathe

• Provide oxygen for combustion

• Remove excess water vapour

• Avoid overheating

Common Examples of Ventilation

Trickle Vents

Small, adjustable vents installed in window or door frames to provide continuous, controlled ventilation. These are always left open, except in extreme weather.

Door Undercuts

A small gap intentionally created between the bottom of a door and the floor to allow air to circulate between rooms.

Soffit Vents

Openings found in the underside of a roof's overhang (the soffit), allowing air to circulate in and out of the attic space.

Extraction Fans – dMEV

Decentralised Mechanical Extract Ventilation (dMEV) fans operate continuously in each wet room. They run at a low (trickle) speed unless boosted by a switch or humidity.

Extraction Fans – IEV

Intermittent Extraction Ventilation (IEV) fans are activated by a light switch, timers, or humidity sensors.

Positive Input Ventilation (PIV)

A whole-house system that encourages air movement from inside to outside, typically from a loft-installed unit.

Mechanical Ventilation Heat Recovery (MVHR)

A whole-house system that:

• Extracts warm, damp air

• Draws in fresh air

• Uses a heat exchanger to recover warmth before expelling stale air and warming incoming air

The Installation

An air pressure test may be conducted before and after installation to check air leakage.

A retrofit design is created after the technical survey. This outlines what ventilation is required and where.

If you have specific access needs, let YES know.

Installers will need access inside and outside your property. Locations will be confirmed in your installation plan. Minor electrical works may be needed for mechanical ventilation.

Typical installation takes 1–2 days, but this may vary. Please confirm with YES or your installer.