Air Tightness in Construction – Eight Fascinating Facts
When it comes to building houses and business premises, modern construction practices demand energy efficiency to comply with building & environmental legislation. The Department of Housing, Planning and Local Government is the lead Department for the implementation of EU Energy Performance of Buildings Directive which sets the energy and carbon dioxide emissions requirements for new and existing buildings subject to the Building Regulations. Air Tightness is a vital issue when it comes to energy performance.
- Essentially, Airtight Construction requires a clear airtightness strategy and the airtight line needs to be continuous, even when formed of different materials. It needs to be joined up, even where there are penetrations.
- Airtight construction is draught-free construction and is essential to protect the building envelope, ensure radical energy efficiency and provide inhabitants with exceptional levels of comfort.
- Airtight construction means that there are no unintended gaps in a building envelope which allow air to leak in or out of the building. This prevents cold draughts and ensures that air from inside the building cannot leak into the mate4rials of the building envelope.
- Airtightness requires the identification of an air barrier (or airtightness line) that is continuous and joined up to form a complete loop.
- Penetrations through the air barrier are possible but should be planned to ensure that the penetrations aren’t caused by unintended air leakage.
- Airtight construction can be formed from many different components and materials which should be clearly identified on drawings as forming the airtight line.
- Some materials typically used for airtight construction include wet plaster on masonry construction, reinforced concrete, Oriented Strand Board (OSB) of a suitable thickness and specifically designed airtight membranes.
- In addition to the materials that make up the fabric of the building, doors, windows, curtain wall systems and roof lights need to be airtight components.
Airtightness in dwellings is important from a number of points of view. Amongst other advantages, better airtightness can:
- Reduce heating energy requirements in the dwelling
- Improve air quality in the dwelling, if achieved in conjunction with a properly designed and implemented ventilation system.
- Improve sound insulation – both from noises entering the house, and if your kids practise their rock band sounds inside, from exiting the house.
- Depending on the airtightness measures used and the overall construction build-up, an expertly installed airtightness layer can also act as a vapour barrier/check to reduce the risk of interstitial condensation. Specifically designed breathing walls that allow the passage of water vapour do not use the airtightness layer as a vapour barrier/check.