According to the Strata Scheme Regulations Act 2016 Part 4, 28(e) Double glazed windows are deemed to be a minor renovation and hence do not require approval by the OC.
Yes, they are classified a “minor” renovation but they still require approval under section 110 of the Act (but not a special resolution or by-law, as I previously thought).
(1) The owner of a lot in a strata scheme may carry out work for the purposes of minor renovations to common property in connection with the owner’s lot with the approval of the owners corporation given by resolution at a general meeting. A special resolution authorising the work is not required.
(2) The approval may be subject to reasonable conditions imposed by the owners corporation and cannot be unreasonably withheld by the owners corporation.
Now, the wording is a little confusing as “approval … given by resolution at a general meeting” could mean that the strata committee could approve the installation, provided it has been given the standard powers to do so. However, they could impose reasonable restrictions, such as that the lot owner agrees that they will maintain the windows at their own expense and that they will not change the external appearance of the block.
But, in a nutshell, you don’t need a by-law but you do need committee approval (at least) which must not be unreasonably refused.