Frequently Asked Questions
Q: What is airtightness?
A: Airtightness refers to the degree to which air leakage is prevented through the building envelope, including the walls, roof, and windows.
Q: Why is airtightness important?
A: Airtightness is important because it helps to improve energy efficiency by reducing heat loss, which can lead to lower energy bills and a more comfortable indoor environment. It can also help to improve indoor air quality by reducing the infiltration of pollutants and allergens.
Q: How is airtightness measured?
A: Airtightness is typically measured using a blower door test, which involves a fan that is used to depressurize the building and measure the rate of air infiltration.
Q: What is a good airtightness level for a building?
A: The ideal airtightness level for a building will depend on a variety of factors, such as the climate, building type, and intended use. However, a commonly used metric is air changes per hour (ACH), with a target of 0.6 ACH at 50 Pascals of pressure (ACH50) often used for high-performance buildings. In Ireland the airtightness requirement in Part L of the Building Regulations is expressed in terms of the maximum allowable air permeability rate, which is measured using a blower door test. The maximum allowable air permeability rate for new dwellings is currently set at 5 m³/hm² at 50 Pa, while for non-dwellings it is set at 7 m³/hm² at 50 Pa.
Q: How can airtightness be improved?
A: Airtightness can be improved by using air barriers, such as housewrap or spray foam insulation, to seal gaps and cracks in the building envelope. Proper installation of windows and doors, as well as sealing around pipes and vents, can also help to improve airtightness. A blower door test can be used to identify areas of air leakage that need to be addressed.
Q: Are there any downsides to airtightness?
A: While airtightness can provide many benefits, it can also lead to indoor air quality issues if ventilation is not properly addressed. Proper mechanical ventilation is necessary to ensure that fresh air is brought into the building and pollutants and moisture are removed.
Q: Can existing buildings be retrofitted to improve airtightness?
A: Yes, existing buildings can be retrofitted to improve airtightness. This may involve adding air barriers, sealing gaps and cracks, and upgrading windows and doors. A blower door test can be used to identify areas of air leakage that need to be addressed.
Q: Which Tape is best used on Masonry.
A: PHS Fusion or Gerband Variable tape id best for masonry.
Q: Do I need to prime walls.
A: Yes all masonry needs to be primed before applying airtight tape.
Q: What tape is best for Timber frame construction.
A: PHS Split release Tape is best for Timber frame construction.
Q: When would I use an Intelligent Membrane.
A: Intelligent membranes are used in warm roof construction and retrofits. Gerband Vario or PHS Variable
