It’s kind of a grey area. But it’s up to the Owners Corporation, in the form of the strata committee, or the owners acting collectively at a general meeting, to require a renovation by-law. If they do not do so, then the Owners Corporation (in theory) continue to be responsible for the future repairs and maintenance of the common property, that was affected by the renovation. Keep in mind that the warranty that covers the renovated pipes and fittings attaches to the owner who purchased them. Thus, if they are faulty, and there is no renovation by-law, it gets complicated when the OC has to do the further repairs, while the owner is sitting on the warranty.
In practice, it’s worth treating each case separately. Registering a renovation by-law costs money, and must be done within 6 months of the general meeting that approved it, both for the fees for updating the by-law, and often legal costs in drafting the by-law. So this is more commonly done for expensive and extensive renovations. Renovation by-laws can be applied for retrospectively too. And the warranty issue means that even without a by-law the OC can pressure the owner into funding any additional repairs.