Building a house is an exciting project involving a number of different phases: from the initial development of the idea, the search for a plot, the house design, who is actually building the house and at what price, to finally handing over the keys. It is a fascinating process that can turn into an unpleasant task if things have not been properly organized and clear procedures are established for each phase of the project.
The same way that you visit your doctor to check your health the head technician is the person with a degree (technical architect or civil engineer) who knows about the building construction systems and their characteristics, is knowlegeable of the various installations and is able to evaluate the state of conservation and the appropiate maintenance for a building.