Why is Product Modularity Underdeveloped in Construction?

Product modularity (a term often associated with off-site construction/prefabrication) has been discussed in construction for a few decades. In spite of that, its understanding in this new context is still emergent. This paper sets out to explore why that is the case. The paper builds on both (i) recent investigations of this concept in construction, including empirical studies which are critically analysed here, and (ii) seminal works on the definition of product modularity in manufacturing. An important insight is that product modularity can benefit traditional construction (by adopting a space-oriented perspective), and thus should not be considered applicable only to off-site construction. Conversely, off-site construction does not ensure per se the adoption of product modularity (even though the terms might be sometimes perceived as closely related). Based on the analysis of literature and empirical cases, three limitations in the understanding and application of product modularity in construction are: (i) unclear boundaries between modules (namely, which components pertain to which module), (ii) invariant modules (namely, the components forming a module do not change depending on the combination in which it is used), and (iii) interfaces as synonymous with surfaces (despite the fact that an interface might entail more than one surface and vice-versa).