It might be arguable that the OC is responsible to repair since it is a construction defect, but I am not certain. Usually individual owners are responsible to do repair and maintenance to class B units. However, regardless of whether the OC would be obliged to repair, I suggest it should.
By ensuring that all the buildings are safe, the OC would avoid the risk of being found to have been negligent.
I suggest the EC is obliged to immediately notify the OC’s insurer of the problem and its proposed course of action.
Since all units are likely to have the same problem, either now or as a risk in the future, it would be cheaper for the OC as a whole to fix the problem for all units. There are, therefore, no good grounds for anyone to object to fixing it for all units.
While maintenance of class B units usually falls to the individual unit owners, from s.24(1)(g), the OC can pass a special resolution making the OC responsible to repair this specific defect of the roof trusses. “An owners corporation for a units plan must maintain the following: … as authorised by a special resolution (if any)—all buildings on all class B units on the units plan. Example—par (g) a special resolution authorising the owners corporation to paint all buildings on the class B units and to carry out roofing and structural repairs to all class B units, but excluding responsibility for internal painting and minor repairs of class B units“
So, in this case, you would have a special resolution just authorising the repair of this specific defect of the trusses of all units, but excluding all other repairs.
I would strongly recommend that your EC writes again to all unit owners proposing to arrange for an engineer to inspect all units and then for a builder to make all repairs recommended by the engineer. It should notify a general meeting to put a motion authorising that pursuant to s.24(1)(g). I think the resolution should authorise the OC to arrange with the owner of each unit for inspection by a structural engineer and then make the repair of any defects of the roofing trusses with the cost to be taken from the contingency component of your sinking fund.
From s.83(1)(f) “For this division, expected sinking fund expenditure means expenditure for the following purposes that the owners corporation reasonably expects will be necessary to maintain in good condition the common property and any other property it holds: … for a building on a class B unit—any maintenance … that is authorised by a special resolution under section 24 (1) (g)”
Your resolution should also amend the sinking fund plan to include 1) using some of the contingency funding for this purpose, and 2) increasing the sinking fund levy as necessary to rebuild the contingency component over the next several years.
If you have the default rule 10, the EC would use that to appoint first the engineer and then the builder as its representatives to enter the units (at a reasonable time) to undertake the maintenance.
There is a risk that someone will get the wrong end of the stick and not understand that the EC is seeking to minimise the costs to all owners of something they have to address. I suggest acting quickly but with clear communication.
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