Airbrick Ventilation Guide: Suspended Floors, Positioning & Airflow
Airbrick ventilation helps move outside air through underfloor voids and other spaces that are designed to remain ventilated. Correct airflow can help reduce stagnant moisture, but simply adding an airbrick at random is not enough. Vent size, distribution, free area and the route through the wall all need to match the building design. This guide explains the role of airbrick vents and what to check before installation.
What Is an Airbrick?
An airbrick is a ventilated unit sized to integrate with masonry. The TRADE Airbrick Vent 9 x 3 sold by JJ Building Materials provides a brick-format ventilation opening.
Why Ventilate Suspended Floors?
Suspended timber floors typically rely on airflow through the void below to help manage moisture. Ventilation openings should be distributed so air can move across the space rather than only entering one isolated corner.
Airbrick Position
Position is controlled by ground level, floor level, wall construction and the required route into the void. Keep external openings clear of soil, paving, vegetation and later landscaping.
Opposing Ventilation
Where the design requires cross-ventilation, openings on different sides of the building help create a through-flow route. Internal sleeper walls may also need provision so air is not blocked between subfloor areas.
Extensions and Raised Ground Levels
Extensions, patios and new paving can accidentally obstruct existing underfloor vents. If a new wall crosses an existing ventilation route, the design may need ducting or telescopic components to maintain airflow. Plan this before construction rather than sealing vents and dealing with damp later.
Free Area Matters
The visible size of an airbrick is not the same as its effective free ventilation area. Use the product data and project ventilation calculation when determining how many vents are needed.
Keep Vents Clear
Paint, render, insulation, insect debris, soil and stored items can reduce airflow. Inspect completed vents and keep them unobstructed during the life of the building.
Airbrick Checklist
- Confirm required ventilation area.
- Distribute vents around the building as designed.
- Maintain airflow through internal subfloor walls.
- Keep vents above and clear of external obstructions.
- Do not block existing vents when extending or landscaping.
Shop Airbrick Vents
Browse brick ventilation accessories at JJ Building Materials, including the TRADE 9 x 3 airbrick vent.
FAQs
How many airbricks do I need?
It depends on the required free ventilation area and layout. Use the building design rather than a fixed number per room.
Can an airbrick be below paving?
The opening should remain clear and effective. If levels conflict, the detail may need a suitable duct or telescopic arrangement.
Can I block an old airbrick?
Not without checking what it ventilates. Blocking underfloor ventilation can create moisture problems.
Do airbricks stop damp?
They support ventilation but are not a complete damp-proofing solution. Drainage, DPCs and other details also matter.
Should airbricks be on both sides of a house?
Cross-ventilation often benefits from distributed openings, but the exact layout should follow the design.