In today's house building curtain walls are almost exclusively used, with a lover level ofprefabrication in Sweden, since complete elements are often associated with high risk.High level of prefabrication has led to extensive moisture damage, in some cases.However, a higher level of prefabrication with retained moisture security could shortenthe construction process, streamline construction and help to industrialise the housebuilding. The prefabricated sandwich wall known for its excellent moisture resistancecan be one solution to the problem. An exterior wall with sandwich panels is dense at anearly stage. This means that the interior work can start earlier, which can lead to a moreefficient construction process.A large number of apartment buildings in Sweden are built up with facades made up ofcurtain walls. The construction process of the walls contains a number of activities thatare focusing on the efficient use of company resources. Flow efficiency focus on theobject that is added value, which means to reduce or remove all unnecessary activities. Acontractor would be able to streamline the construction process with a flow efficiencyperspective. This perspective combined with the industrial properties of the sandwichwall, could increase quality-safe and contribute to a better working environment. Thesandwich wall has a disadvantage: high relative purchase price. A case study wasconducted in order to compare the purchase price of the sandwich wall with theadditional activities that the curtain wall requires.The case study was done at Peab Bostad AB at one, for the author, known project in order to compare the lead times of the walls. Other properties of the elements such as moisture, acoustics and environment were observed. Data was collected through several interviews of employees. The model of analysis is based on a literature review of the body of knowledge regarding resource- and flow efficiency and industrialised house building.The results indicate that the sandwich element has a two months shorter lead timecompared to the curtain wall. This compared to the sandwich walls´ properties such as less variation, reduced risk of emerging of bottlenecks and led work in progress, argues for the contractor to focus on flow efficiency. The lead time is reduced, partly due to the reduced dehydration time and partly due to the reduced amount of activities. Sandwich walls supports the industrial house building process since it can be prefabricated with higher level because of its moisture resistance.The results indicates also that the purchase cost of the sandwich wall is more than twiceof the purchase cost of the curtain wall. However, the sandwich wall has a lower overallcost since of its other costs, which are dependent on the lead time.Before the study began, there were some expectations both from author and respondents on a positive outcome to the sandwich advantage, which may have caused V bias. The bias is that work environment is better and the lead time of the sandwich wall is expected to be shorter since it requires fewer completions.It is also arguable that a more frequent use of the sandwich wall could shorten down the lead time further. By creating procedures and standards that can be repeated in processes and where the lead times of the wall has little variation are known we can increase the industrialisation, meaning, taking control of processes to ensure quality and keep costs down.