One arrangement, not several
The instinct in a building of small occupiers is for each to take a share of the work, perhaps a week each or a floor each. It rarely holds. Standards drift, a tenancy changes hands, and within a few months the entrance reflects whoever cared most rather than any agreement. A single arrangement with one contractor and one specification is more reliable and usually cheaper per occupier than several fragments.
That means someone has to hold it. In a strata building it is the owners corporation through its manager; in a leased building it is the landlord or their agent. Where neither is active, the tenants can appoint one of their number in writing to instruct the contractor. Whoever holds it, the arrangement should be documented, because a shared service without a named holder eventually becomes nobody's.
