The mistakes and failures on the roof are noticed during inspection of the construction, many of the commentaries are recurring. A contractor should only need to get a commentary once and then learn from the mistake. It has in this study been brought to light that the solution is not to tell the contractors to "stop slattern", it is more complicated than that. Today, the biggest problems are found in leadership, communication, feedback of experience and that the entrepreneurs take too little responsibility.To minimize the amount of commentaries all contractors need to work with a clearer leadership where the leader is both respected and appreciated. The leader must in an effective way be able to convey all the information to all employees.