Yes they will need a special resolution by-law (75 percent vote in favour).
Plus, on the basis of a ruling in the High Court, they will need to pay the owners corp the value of the roof renovationcalculated thus x-(y+z) where
x = an accepted estimate of the value of the renovated unit
y = an accepted estimate of the value of the unrenovated unit
z = the cost of the renovation (including legals and by-laws)
It’s a good way of giving them what they want and allowing the sinking fund to get a boost too.
Naturally, the by-law will transfer all responsibility for maintenance of the roof space to the renovators.