Common Air Leakage Locations and Typical Remedial Works
Some air leakage is intentional and forms part of the building’s design.
However, unintended gaps in the building envelope allow uncontrolled air leakage, which can reduce comfort, increase energy use and allow dust, outdoor pollutants and noise to enter the home.
If you’re planning maintenance or renovations, understanding where homes typically leak can help you identify opportunities for improvement. Every building is different, but many air leakage pathways are common across Australian homes.
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Air can leak through any gap or opening in the building envelope. Some of the most common locations include:
Around external doors and windows
Around plumbing, electrical and other service penetrations (for example at air conditioning pipe penetrations)
Exhaust fans in bathrooms, laundries and kitchens particularly where dampers are missing or not operating properly
Power points and recessed downlights
Ceiling access hatches
Wall-to-floor, wall-to-ceiling and stair-to-wall junctions (around skirting boards and architraves)
Around fireplaces and chimneys
Some homes have one or two major leakage pathways, while others have many smaller leaks distributed throughout the building.
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The most appropriate solution depends on the construction of the building and the cause of the leakage.
Typical approaches include:
External doors and windows
Replacing weather seals
Adjusting hardware
Sealing perimeter gaps where appropriate
Pipe and duct penetrations
Sealing gaps around penetrations using appropriate air-sealing products
Ceiling access hatch
Installing compression seals or an airtight hatch system
Exhaust fans
Installing or repairing backdraft dampers where appropriate
Downlights
Sealing penetrations or replacing with airtight fittings where appropriate
Fireplaces
Sealing unused fireplaces using removable solutions if no longer in use
The goal is to reduce uncontrolled air leakage while maintaining the intended performance of the building.
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Improving airtightness should not be considered in isolation.
Buildings are complex systems in which insulation, airtightness, ventilation, moisture management and occupant behaviour all influence each other. Changing one part of the system can affect the performance of the whole building.
As homes become more airtight, uncontrolled leakage is reduced. While this improves comfort and energy efficiency, it also means air and moisture can no longer travel through accidental gaps in the building envelope.
Therefore, ventilation becomes increasingly important as airtightness improves. Depending on the building and the extent of the improvements, interventions may involve natural ventilation, mechanical ventilation, or a combination of both to help maintain good indoor air quality and manage indoor moisture.
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Some openings are intentionally incorporated into the building and perform important functions. These may include drainage openings, subfloor ventilation, roof ventilation systems and other features required for the building to function safely and effectively.
Improving airtightness is not about sealing every gap. It is about identifying and reducing uncontrolled air leakage while preserving intentional openings that serve a purpose.
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Focus on reducing unintended air leakage rather than sealing every opening.
The most important remedial works depend on the individual building.
Airtightness, insulation, ventilation and moisture management work together. Considering one without the others may lead to unintended consequences. Think of the building as a system in order to achieve good overall building performance.
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If you’d like to explore the topic further, I recommend the following resources.
My Efficient Electric Home Handbook by Tim Forcey
An accessible and practical guide to improving the comfort, energy efficiency and electricifcation of Australian homes. Written for homeowners, it explains building performance concepts in plain language and is an excellent starting point for anyone planning to improve their home.
Your Home – Australia’s Guide to Environmentally Sustainable Homes
The Australian Government’s independent guide to sustainable homes, including information on insulation, ventilation, airtightness, moisture management and energy-efficient renovations.
CSIRO articles on home airtightness
CSIRO has published a number of easy-to-read articles explaining why airtightness matters, how Australian homes typically perform and what current research tells us about reducing unwanted air leakage.
Sealing the comfort of our new homes
Comfort and energy efficiency on the rise in new Australian homes