What is an air brick?

Author: Dr. Alicia Rempel  |  Last update: Thursday, July 9, 2026

An air brick is a type of brick, most commonly made from clay or plastic and designed with holes, that provides a form of ventilation. They will usually be found on the ground floor or sit beneath suspended floors to circulate and improve airflow. You may also see them described as 'hollowed' or 'perforated' bricks.

Do houses still need air bricks?

Well, though it's rare, there may be circumstances where an air brick was installed but is no longer needed. For instance, if the previous property owner had a gas stove, but you've moved onto a new form of heating, you might not need the air brick for extra ventilation any more.

Why do people block up air bricks?

Air bricks are there so air can circulate under the house where wooden floors are present, By blocking the air brick you are preventing the air circulation which will lead to a build up of damp rotting the timbers.

What is the difference between air vent and air brick?

Air bricks, sometimes called air bricks or air vents, are special bricks containing holes that allow air to enter under the floor of buildings that have suspended floors. Cavity walls also need ventilation to allow airflow that will prevent moisture build up.

Can water get through air bricks?

According to Know Your Flood Risk, up to 500 litres of water a minute can enter into a property through a single airbrick alone.

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Can I fill in an air brick?

Answer. It would be a bad idea to fill it at all.

What are the disadvantages of air bricks?

A few potential downsides to air bricks to watch out for:
  • Pest Control – sometimes air brick holes can be big enough to let mice in or even things like bees and wasps so watch out for this. ...
  • Water Ingress – if you are not careful, air bricks can let water in.

Why do older houses have air bricks?

Airbricks are essential to permitting air to flow beneath the floors. This reduces the condensationin the sub floor void. It removes excess moisture and helps the timbers to remain drier – hopefully dry enough to prevent that rot, decay and timber beetle infestation.

How much does it cost to fit an air brick?

Higher Costs: Professional installation can be expensive, with costs ranging from £200 to £500 per project. Labour alone can cost between £150 and £300.

Do air bricks make a room cold?

They act like barriers, trapping heat inside your home and blocking chilly breezes. This means you don't have to block the air bricks completely, keeping good ventilation while still staying warm.

Do air bricks let mice in?

The majority of air bricks manufactured for UK properties allow mice and insects to access cavities and the building's internal cavities, so a physical barrier must be placed to prevent ingress and stop a common point of entry.

Where is the best place to put an air brick?

Ideally, air bricks should be positioned below the floor joists. This ensures that the air can flow through the cavity below the floor. However, the air brick should also be at least 75mm above ground level. This is to stop dirt, leaves or other debris from outside building up and blocking the vents in the air bricks.

What is an alternative to air bricks?

Airbricks have traditionally been manufactured using clay or cast iron. Some modern airbricks are made from plastic which can be more durable and enable a greater rate of airflow. An alternative to airbricks is the use of cast iron grilles, known as air vents.

How do you know if your house has poor ventilation?

Persistent Odors: Homes should refresh and clear out odors naturally through proper ventilation. If cooking smells, smoke, or other odors last longer than they should, it's likely your home isn't circulating air properly.

Will an air brick stop mold?

Air bricks aid in ensuring proper ventilation of the indoor space, thereby reducing the risk of damp-related problems such as condensation, cold spots, and mould growth.

What happens if you block up air bricks?

All properties with suspended timber floors at ground level require an adequate flow of air beneath the timbers at sub-floor level. If the air bricks are blocked or closed this will reduce the ventilation and the risk of serious rot and damp will be increased.

What is behind an air brick?

The spaces inside air bricks allow air to circulate within a building, which helps to regulate the temperature and prevent the buildup of moisture. This can lead to various problems, including mould, mildew, and rot, which can cause structural damage and create health problems.

Why do old houses have so much dust?

Common Sources of Dust in Homes

Outdoor sources may include pollen, soil particles, and pollutants that enter through open windows, doors, or on shoes and clothing. The age of your house and its HVAC system can also contribute to dust accumulation, as older homes may have more cracks and crevices where dust can settle.

Do air bricks let rain in?

Air bricks set at, or close to, ground level may flood and allow rainwater to enter the under floor void. ∎ Air bricks located below general ground level with small recesses in front, often formed with raised kerbing/edgings etc., are at risk of blockage from debris accumulating in the recesses.

How high should air bricks be off the ground?

Air bricks between ground level and 75mm above ground level is acceptable if ground slopes away from building and is suitably drained and the ground is hard landscaped. Preferred approach where air brick is at least 75mm above ground level.

Do air bricks go through walls?

Air bricks are small, specially designed bricks with holes that allow air to flow through them. They are essential for providing ventilation in cavity walls to prevent moisture buildup and maintain the integrity of the structure.

How do you rodent proof air bricks?

Easy to Install: Stainless Steel Mouse Mesh Air Brick Vent Cover. Remove and loose particles and dust from air brick vent, then simply attach MouseMesh Air Brick Vent Cover using a strong, weather-proof adhesive or screws. Can be installed over damaged air bricks too!

How do you protect air bricks from flooding?

There are two ways of protecting air bricks from allowing flood water into a property. Temporary covers can be fitted over the air bricks in time of flood, or new air bricks can be installed which are flood proof.

How many air bricks should a house have?

Q: How many airbricks will I need? A: Every build is different but as standard, one airbrick per 1.5 m – 2m (dependent on the length of the wall) should be sufficient.

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