And this is what it says in the NSW Strata Act:
Part 1 Responsibilities of owners, occupiers and other persons relating to lots
116 Owners, occupiers and other persons not to interfere with structure of lot or services to lot
(1) An owner, mortgagee or covenant chargee in possession (whether in person or not), lessee or occupier of a lot must not do anything or permit anything to be done on or in relation to that lot so that:
(a) any support or shelter provided by that lot for another lot or common property is interfered with, or
(b) the passage or provision of water, sewage, drainage, gas, electricity, garbage, artificially heated or cooled air, heating oil and other services (including telephone, radio and television services) through or by means of any pipes, wires, cables or ducts for the time being in the lot is interfered with.
(2) The owner of a lot must not alter the structure of the lot without giving to the owners corporation, not later than 14 days before commencement of the alteration, a written notice describing the proposed alteration.
NB: There’s no requirement for written permission, just 14 days notice.
In the Schedule 1 By-laws (which are only operative if adopted by the Owners or by default if the Owners have not adopted any by-laws):
5 Damage to common property
(1) An owner or occupier of a lot must not mark, paint, drive nails or screws or the like into, or otherwise damage or deface, any structure that forms part of the common property without the approval in writing of the owners corporation.
they go on to say …
(3) This by-law does not prevent an owner or person authorised by an owner from installing:
(a) any locking or other safety device for protection of the owner’s lot against intruders, or
(b) any screen or other device to prevent entry of animals or insects on the lot, or
(c) any structure or device to prevent harm to children.
In the NSW Model by-laws for residential strata schemes in the 2010 Regulations (which are also not in force unless adopted by the Owners Corporation), there’s an additional sub-clause that allows some work:
(d) any device used to affix decorative items to the internal surfaces of walls in the owner’s lot, unless the device is likely to affect the operation of fire safety devices in the lot or to reduce the level of safety in the lots or common property.
And then, of course, there are the individual by-laws for each strata plan which can cover things like how and when you can do noisy work, how to get materials in and rubble out and, as we never tire of telling you all, differ from building to building.