Airtightness becomes a more and more important parameter in the rationalization of the energy consumption. The quality of the works during the construction process is essential. However, this particular step is on itself absolutely not sufficient to build airtight buildings. Airtightness has to be taken into account from the pre-project. For that, architects have to deal with a large bunch of items. Steps as the definition of the ambition level, the precise positioning of the airtightness barrier into the building are essential. Possible contradictions with permanent ventilation requirements have to be taken into account. For instance, in Belgium, there are natural ventilation requirements for fire safety reasons or for open heating devices (as stoves) and it could be difficult to conciliate these requirements with the performance of airtightness. In addition, some equipment such as distribution board must be adequately placed to avoid some air leakages. At last, the choice of equipment types and their position could be crucial to achieve the airtightness level considered. The construction process on itself, intermediate blower door tests during the construction process, the final blower door test as well as the attention points during the occupancy have also to be taken into account. Thereby, a path of 10 steps starting from the very beginning of the conception up to the utilization of the building have been identified to facilitate the realisation of affordable airtight buildings.