Purpose: There are many ways to make the construction process more efficient and one of these ways is to streamline communication. The purpose of this bachelor thesis  is to analyze and develop communication between building and plant works on large construction companies. One of the most key factors for implementing a successful project is that there is a well-functioning communication. There is a terrific opportunity to save both time and money by streamlining communication.  Method: This work consists of a case study, the case studied consists of a company that has a construction- and plant works department where the communication between these departments has been investigated The case study that gave in-depth knowledge through studies consisting of; Interviews where experienced circumstances were described and document analysis showing how communication should be done according to NCC and a literature study where previously known communication problems and communication tools were studied. Findings: Communication between building and plant works is influenced by many factors, such as previous experiences, different references and ways of thinking. These factors can lead to problems in the form of irritation, disagreement and ambiguity in a workplace. To streamline communication and to largely eliminate these factors, it is recommended to have; short day meetings, training in communication, organization start and cooperation at an earlier stage, and that the person who’s sharing the information is directly linked to the recipient, which means that there is possibility of additional questions if uncertainty arises. Implications: Communication is often broken between the businesses buildings and plant works, often due to misinterpretation of information or when different perceptions arise as to who’s in charge and when to do what. To achieve better communication, education, application of short-day meetings and clearer information could be of significant use. A suggestion for further research is to test how the template for shortday meetings would work in production and what results it would get. Another suggestion is to investigate what it looks like at other major construction companies with communication between construction and plant works or test the template on other companies. Limitations: The report only studies how communication takes place during the production phase between buildings and plant works within NCC's local department in Jönköping. Since the demarcation of work was chosen for communication during the production phase, only employees who worked mainly during the production phase were interviewed.  Keywords: Communication, internal communication, building, plant works, production.