However, the report also says the £2.3m scheme had no defects, no need for maintenance for six months, and was popular with its tenants.
The report into the scheme, which was developed by housing association The Peabody Trust, reveals that the 30 flats cost £77 184 each. Deducting an additional rental income of £129 000 that was gained because the construction time under prefabrication was faster than traditional methods, the modular scheme was 5% more expensive overall.
The BRE's Centre for Sustainable Construction, which carried out the report, attributes the higher cost to the pioneering nature of the Cartwright Pickard-designed project, design innovations and the high-quality nature of the specification. However, Peabody Trust believes that it can recoup the 5% on future projects "by making significant savings in future developments".
The research body also found that a delayed start to the external steel and cladding works was largely responsible for a 10-week delay to the project, which was completed in December 1999.
It argues that the construction process could have been improved by using more prefabrication, in particular for the external cladding, galleries and balconies, which were built using traditional means.
The contractual relationships between the members of the construction team would have benefited from being clarified at an earlier stage, the report says. In particular, the prefabricated scheme needed more design time early on, and less later in the process, than would usually be the case with traditional projects.
It also showed that the time and quality benefits of off-site construction required the manufacturer to be involved "from the earliest stage" of the project.
The report praises Murray Grove for having zero defects and no maintenance call-outs in the first six months of occupancy. Snagging was also far lower than traditionally built schemes, the researchers add.
The tenants interviewed by the BRE were overall "very satisfied" with what they described as "attractive, modern and well-equipped flats". None was put off by the knowledge that Murray Grove was prefabricated.
After living there for six months, tenants praised the "high quality of finishes" and the "excellent layout" of the flats. The main criticisms were poor ventilation, the noise from surrounding buildings, and the media attention on the project.
The contractor was Kajima, and the manufacturer was Yorkon.