For owners of a strata property, if the work you intend to do affects the common property then, in addition to considering whether you need development approval for the work, you must have the approval of your owners corporation to conduct the work. As the owners corporation owns the common property you cannot alter the common property without its permission.
If your planned work is major renovation work, then any approval will by way of a motion passed at a general meeting for a by-law under either section 65A or 52 of the Strata Schemes Management Act 1996 (NSW) authorising the works. If a development consent is required then the owners corporation as the owner of the common property affected by the renovations will also have to consent to the development application.
If development consent is not required as your planned work is minor, such as installing new cupboards or new shelving along a common property wall, then model by-law 5 applies. This means you must request written approval from your executive committee prior to doing this work. If your scheme is not governed by the model by-laws check for an equivalent by-law.
You should also consider if there are any by-laws setting standards. Model by-law 17 provides that you must not maintain anything in a lot that is not in keeping with the appearance of the building. Installing a trellis may breach this by-law. If your strata scheme is only part of a building, you must also comply with any architectural guidelines in the strata management statement.
If you live in a community association you should keep in mind the architectural guidelines for your association. These guidelines will often provide for the approved shades of paint or material that must be used.