When renovating a house or building a passive or low energy house, it is not only important that it is well insulated but also that it meets the building standards for air tightness. Airtight construction means that when building a house, the occurrence of drafts and other unwanted air flows are taken into account as much as possible. By sealing all joints, cracks and pipe connections as much as possible with a suitable filler, tape or foil during the construction process, you immediately make a good start when making a home airtight.
In practice, the air tightness is often tested by applying the ‘blower through’ test. A fan is placed in the door hole with which first an overpressure and then an underpressure is created. The pressure difference is measured with the aid of a pressure gauge and the ‘N50 value’ is finally determined on the basis of a calculation. The lower this value is, the more energy efficient the home is. In a passive house (very energy efficient) this value is less than 0.6.
Places that are sensitive to air leaks
A lot of research has been done into the airtightness of houses. It has been established that many draft problems are caused at the roof, in transit in the floor and in places where windows and doors join the wall. Since these places are closely connected to insulation, it goes without saying that airtight insulation is the solution here:
Roof insulation and air-tightness
The roof of the house is a place where you can save a lot of energy (up to 25%). This can be achieved by providing the roof with insulating material, such as glass or rock wool. This is the moment to pay the necessary attention to an airtight finish.
See if you can fill it with PUR then cut the foam as much as possible. After applying the insulation material, it is very important to finish the layer airtight with a good polyethylene film or so-called climate film. All seams and cracks must be taped, even near the walls. This way you create an air-tight and vapor-barrier layer that benefits the airtightness of the house.
Usually most air leaks occur at openings in the floor that serve as a passage for the piping. You can think of forwards for the water or gas pipeline and holes that are installed for sewer pipes or other drain pipes. This often leads to drafts from the crawl space, which has a negative effect on the overall airtightness of the house. These draft holes for passages are usually relatively easy to seal with PUR foam.