**6. Conclusions**

The main outcome of this investigation is a framework of decision categories related to customer integration and the definition of the scope of customisation, considering the context of house building projects. These decision categories emerged from a list of MC practices that were identified in the literature and refined in an in-depth empirical study carried out in a Brazilian company that adopted some MC ideas as part of its business strategy. Some of the decision categories have been proposed in previous studies, and refined in this investigation, while two of them, knowledge management, and customer interaction and relationship, have been originally proposed in this research study.

The main theoretical contributions are concerned with exploring the underlying ideas of those practices, which have been used to explain the decision categories and their relationships. Additionally, the list of practices can be used to assess the degree of implementation of core and customer integration practices in house building companies in order to identify gaps in the existing strategy.

This exploration portrays the fruitful context of MC in construction. There are plenty of opportunities to improve value generation, not only for companies that use industrialised construction methods but also in the case of traditional ones. Customer integration seems to be a key area of improvement in house building companies, demanding e fforts from di fferent areas, which are not limited to the development of configurators or digital tools.

A major limitation of this investigation is that it was based on a single empirical study. More insights about customer integration could be obtained if other in-depth empirical studies were carried out in companies from other market segments or countries, providing opportunities for refining the framework and the assessment method.

Some opportunities for further research emerged from the discussions of the framework, such as the need to explore the interfaces between functional areas (customer integration, operations managemen<sup>t</sup> and product design) and also between decision categories. Those interfaces need to be considered as it is expected that e ffective MC should have a holistic character. Other opportunities include the development of specific frameworks for product design and operations managemen<sup>t</sup> for mass customised housing.

Another theme to be explored is how the customisation level contributes to di fferent challenges and issues on the adoption of di fferent sets of practices for customer integration. The higher the level of customisation and the degree of integration, the higher the complexity that needs to be dealt with due to the increasing number of stakeholders and product customisable items. Therefore, di fferent types of MC strategies should be explored by considering the need for using di fferent sets of practices or adapting some of them to specific contexts.

Finally, some other future research opportunities were identified regarding specific decision categories. For instance, not much has been explored regarding the configuration sequence decision category and the interdependences between customisation units that need to be considered in the design of choice menus. Another opportunity is the relationship between the solution space and the level of customisation, which has been superficially explored in the literature. Regarding the customer based knowledge decision domain, there are still many opportunities to explore approaches based on information-driven decision making and recommendation systems. Finally, the customer interaction and relationship decision category represents a fertile ground for the further exploration of experience design in mass customised housing.

**Author Contributions:** Conceptualisation, C.d.S.H.; methodology, C.d.S.H. and C.T.F.; analysis, C.d.S.H.; investigation, C.d.S.H.; writing—original draft preparation, C.d.S.H., C.T.F. and M.E.E.; writing—review and editing, C.d.S.H., C.T.F. and M.E.E.; supervision, C.T.F. and M.E.E. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was partially funded by CAPES (Coordination for the Improvement of Higher Education Personnel) an agency under the Brazilian Ministry of Education.

**Acknowledgments:** We would like to thank Company P for being a partner in this research project, and Luciana Gheller Amorim and Manoela Conte for the cooperation and support during the empirical study.

**Conflicts of Interest:** The authors declare no conflict of interest.
