With an increasing population and need of housing, Sweden needs more availible apartments and cost efficent solutions. The organisation for public housing in Sweden has responded to this situation a couple of years ago with predefined buildings called ”Kombohus” available to purchase for the companies that work within public housing. The approach for this study is to compare these to ordinary construction projects with focus on the extra costs and eventually use the full potential of these buildings with less extra costs. The casestudy is based on AB Gavlegårdarnas organisation and construction projects. Three Kombohus and two traditional projects are compared to see the difference in the final price, which project has the best prediction of the final cost, and how the work of improvement can be used to minimize the extra costs. The study shows that Kombohusen are the cheapest to build, but also have more space to reduce the cost even more. The traditional projects are completed within 1% of the offered and predicted cost. Kombohusen differ from plus 16% and 17% to minus 11% below the offered cost. As an improvement it is suggested that a more uniform documentation when the projects are finished is needed, as a way to see what has been included or not in the different posts. When more similar projects are completed, the knowledge of what made the major extra costs will prevent the same type of cost to appear. The knowledge and experience feedback is very important for future projects and the chance of making a correct estimated cost. / <p>Presentation på distans med videomöte.</p>