One of the challenges for the recycling industry is the lack of sufficient (specific) recycling applications for materials recovered from plastic waste streams. This research explores the potential of recycled plastic materials, particularly polyethylene-aluminum (PolyAl) and mixed plastics (DKR350), for use in construction, focusing on post-consumer, source-separated waste streams. As plastic waste is a major environmental challenge, the construction industry offers an opportunity to reuse these materials. The study examines the technical performance, design flexibility, environmental sustainability and economic viability of PolyAl and mixed plastics and compares them with traditional materials (wood, concrete and steel). It also evaluates how different production techniques affect the properties and applications of these recycled materials in construction. The central research question is: "What recycled plastic materials and related production techniques are available to be used in housing design and construction?". By addressing barriers to the application of recycled plastics, this research aims to promote circular economy initiatives and encourage the use of recycled materials in sustainable, environmentally responsible modular housing solutions.

The building industry is one of the largest producers of waste materials worldwide. Construction waste can include various materials such as concrete, wood, glass, metals, plastics, and hazardous materials. These wastes streams can pose significant environmental challenges and contribute to pollution and depletion of natural resources. However, they can also be considered potential resources that can be reused, recycled and/or repurposed, contributing to a circular economy and sustainable development. Dealing with construction waste in the built environment has become a crucial aspect of contemporary architecture. It requires a balance between the need for resource efficiency and waste reduction on the one hand, and the design and functionality of buildings on the other. However, waste could also be considered to be a potential ‘raw material’. From this perspective it is to be argued if ‘waste’ is a valid term? Maybe is the way society interprets ‘waste’ just a perception based upon a sincere lack of knowledge how to transform and reuse these residues?
This paper examines the issue of construction waste and whether the perceptions associated with the term are related to the actual reality or are the result of a severe bias.
The research question of this thesis is: Are waste materials in the built environment a problem (pollution) or a solution (resource)?