How Air-Tightness Issues Can Impact Your Building Defect Report

Air-tightness refers to the degree to which air can enter or escape a building in an uncontrolled manner. This typically occurs through gaps or cracks in floors, ceilings, walls, or around windows and doors. Maintaining an appropriate level of air-tightness is particularly important for energy efficiency, as excessive air leakage can significantly impact heating and cooling performance.

Importance of Air-Tightness

In climate-controlled environments, a lack of air-tightness can lead to substantial energy loss. Draughty buildings require more energy to maintain comfortable indoor temperatures, resulting in higher utility costs. Studies indicate that air leaks contribute to approximately 15�25% of winter heat loss in buildings.

Beyond energy efficiency, uncontrolled air infiltration can introduce dust, pollen, and pollutants, potentially affecting indoor air quality and occupant health. However, excessive air-tightness without adequate ventilation can lead to issues such as condensation and mould growth. Achieving the right balance between air-tightness and controlled ventilation is essential for a healthy indoor environment.

Air-Tightness Testing

To assess the air-tightness of residential buildings, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) conducted comprehensive testing on 105 apartments and 128 detached houses. The procedure involved turning off systems such as air-conditioning and exhaust fans, closing all windows, doors, and vents, and using a fan to regulate internal air pressure to a standardised level. Airflow in and out of the buildings was then measured with specialised equipment.

These results were compared to a similar CSIRO study conducted in 2015, which assessed 129 newly built homes.

Key Findings

The study revealed a 65% improvement in the air-tightness of newly constructed dwellings across Australia.

• Apartments demonstrated the highest levels of air-tightness, followed by single-storey houses, with two-storey houses showing the most air leakage.
• Larger homes generally exhibited more air leakage due to increased surface area; however, some large homes were well-sealed, while some smaller homes were more permeable than expected.
• Common leakage points included bathroom fans (66% of tested homes) and sliding glass doors (63% of apartments, 50% of houses). The most significant issue in houses was poor or missing door seals, identified in 65% of tested homes.

While newly constructed homes are considerably more air-tight than older ones, these leakage sources remain common in both new and existing buildings.

Enhancing Air-Tightness: Practical Solutions

Addressing air leakage can be achieved through simple yet effective measures:

• Installing hoods or dampers on exhaust fans to prevent unintended air passage.
• Using sealants to fill gaps in walls and installing sealing strips around doors and windows.
• Employing traditional solutions such as door snakes to minimise draughts beneath doors.

Regulatory Improvements and Industry Standards

Several regulatory measures have been implemented to enhance air-tightness in new buildings:

• Mandatory continuous mechanical ventilation in new dwellings, particularly apartments.
• Integration of building wraps, which act as protective layers against air and moisture infiltration.
• More stringent air-tightness specifications within the national energy star-rating framework.

Building Defect Report Implications

The air-tightness of newly constructed Australian homes has significantly improved, representing a major advancement in energy efficiency and occupant comfort. By implementing best practices in sealing and ventilation, homeowners can enjoy energy-efficient, comfortable living spaces that require less energy and reduce overall costs.

Importantly, air-tightness can directly influence the findings in a building defect report. Poor sealing, inadequate ventilation, or obvious leakage points may be listed as defects, especially if they compromise energy performance, indoor air quality, or compliance with regulatory standards.