Kenny – the “process” that’s been referred to involves the Owner concerned providing the Owners Corporation (via its Strata Manager in your case) with details of the renovations proposed including plans / specifications, plus contractors’ details including licenses and liability / workers compensation insurance certificates.
That information may be initially considered by your Executive Committee (E/C) with the assistance of its Strata Manager, who would usually advise whether or not the proposal may be consented by the O/C and if so under what conditions such as permitted work days/times (noise impacts upon neighbours), disposal of building residues, contractors’ parking, Council approval, and who’s to be responsible for the on-going maintenance / repairs of affected areas including of the Common Property (e.g. the roof).
As your Strata Manager has mentioned the need for a Special By-Law I’m assuming that none of relevance is Registered on your Plan’s Strata Title, and so a draft needs to be prepared by an experienced person (e.g. a Strata Lawyer) in order to formalise the aforementioned conditions, and to most critically make the current and all subsequent Owners of the Lot concerned responsible for all future maintenance / repairs of its renovated components, and not the O/C as would otherwise be the case.
In order for renovations and the Special By-Law to receive the consent of the O/C, a min. 75% of those voting (including by proxy) would need to do so in favour (as a “special resolution”) with that calculated on the basis of the Lots’ units of entitlement not by a simple majority (as a “poll vote”).
As for the costs, if the General Meeting is convened just to consider the Owner’s proposed renovations then they pay, and similarly if the Special By-Law relates only to that Owner’s proposal as opposed to being drafted such that it may be generically applied to all renovations involving the Common Property (the approach that I’d suggest, where the O/C pays), then again those Owners pay.
Now your O/C needs to decide what it does to, where possible, consent retrospectively to those other works that have already been undertaken by Owners; ask your Strata Manager or seek an experienced Lawyer’s advice about how best to do that possible in the context of a generic Special By-Law.
As you’ll read over and over again HERE in the specific Topic of this Forum that relates to renovations, it’s most important that all such works by Owners be properly notified to the O/C.
That’s critical in situations such as you describe where a change or addition is proposed to the Common Property (e.g. a roof-mounted skylight) where in the absence of a proper consent under the conditions of a Special By-Law the ongoing maintenance, repair, and replacement of those works and any related areas (e.g. roof tiles / capping) is as I’ve mentioned, by default the responsibility of the O/C ($$).