Those days when land are cheap they use to have separate car park building . Nowadays not so common . Some argue that separate car park building offer one layer extra security . But for people who prefer privacy they like car park to be at the same building .

Honestly, I couldnt find any pro for this development of separate the stand alone building for car parks. Unless security is tightly given and assume all car parks are with ventilation and fresh air, but this pro

Some projects forced to built this stand alone car park building are due to;
1. Land issue such as land slope or ex-mining land like Desa Park City which unable to build basement car parks;
2. Construction cost evolving like DPC scenario above.
Some projects may find it cheaper just to built 2-3 storey car park building (with the condo no basement parking) than initial plan of basement car park which required more floors hence higher construction costs due to stronger engineering works required, as well as to replace it with the facilities floor needed and cut cost from here.