Given the client´s need to reduce on-site construction time to a minimum for this annex to a weekend residence, we proposed a prefabricated structure. The program called for two bedrooms with two full bathrooms and a common terrace. An important design constraint was the dimension of prefab elements, which would have to be transported by road. We planned modules measuring up to 7.2 meters by 2.4 meters, the standard size of a freight truck platform, which also optimized the use of metal sections for the structure and frame. The entire structure was put together in the workshop, with light roofing, some plumbing, electrical installations, as well as preliminary floor, wall, and ceiling finishes in the bathroom areas. On site, the foundations had been laid and prepared to receive the structure. Once there, the modules were assembled, doors and windows put in place, exterior stone was applied, and bathroom fixtures, lighting, and accessories installed, before the final details and finishes were attended to.