dc – you’ve been provided with some sound advice, and you should also consider that, depending upon the positioning of the new wall, you may create another room that won’t be shown on the Strata Title Plan or on the Plan of your individual Lot, that may compromise both the Owners Corporation’s insurance coverage and any insurance that you may hold for contents, and could at least complicate matters should you ever want to sell your Lot.
But with regard to your original questions, as the proposed new internal wall will by necessity be joined to the floor and ceiling of your Lot, and as both of those areas are common property, the Owners Corporation (O/C) must at least be advised of your intentions, and as accidental damage to that common property could occur, the O/C would also want to know the details of the tradespeople who’ll be doing the work and of the currency of their liability insurance, may wish to impose limitations upon the times of work (e.g. to limit noise impacts on neighbours), upon where construction materials are stored, and about the disposal of wastes (e.g. off-site). Sect 65A of the NSW Strata Schemes Management Act (SSMA) applies if your O/C regards your proposed works as “erecting a new structure”.
Additionally, if you intend to alter any services within your Lot, such as putting wiring for new powerpoint/s or television services within the proposed wall, again the O/C must be advised. Sect 116 of the SSMA applies.
In terms of your proposal being rejected by the O/C, provided you follow the provisions of the SSMA in the terms that I’ve advised then any rejection or imposition of unreasonable conditions by the O/C can be taken by you to Mediation by the NSW Department of Fair Trading (DFT).
As you probably appreciate, doing anything at a Strata Property and doing similar things at a stand-alone property (e.g. a house) is very different in terms of the rules and considerations that apply, so for an overview of those have a read through THIS excellent document produced by the DFT.