Catja de Haas works as a sole practitioner and in collaboration with other practices. Her speciality is housing. 

She also works as an artist. Her work, which explores the design and use of the home, the house and domestic objects, consists of art pieces, (miniature) installations.She explores through miniature installations and writing aspects of the home and domesticity that are usually overlooked in conventional architecture. The result of these explorations feed into her (architectural) projects. 

Catja has exhibited and presented her work at the Bartlett, and has lectured at the Architectural Association and the Chelsea college of Art at the University of the Arts London. Over the years she has been a visiting critic at various schools of architecture and universities in the UK and the Netherlands and has completed a PhD by Design at the Bartlett school of Architecture at University College London.

She grew up in the Netherlands and obtained her MSc at the Technical University of Delft in the Netherlands, where she graduated under Professor Herman Herzberger. She obtained a MA in 'Housing and Urbanism' in London at the graduate school of the Architectural Association in London (with a scholarship from Fonds voor beeldende kunsten).

Prior to setting up on her own she worked at Itsuko Hasegawa in Tokyo and Will Alsop in London.