Strata inaction on roof noise

I have an issue similar to one already on this forum (“Roof truss issue”), but somewhat different, and am hoping someone can lend their view.

Background:

My fiancée is the owner of a unit on the top floor of a multi-floor strata-managed apartment building in Canberra, ACT. The building is only a few years old.

Above the ceiling there is a cavity containing the usual – insulation, air-con ducting, various wooden beams/trusses, etc.

There is an intermittent creaking/knocking noise coming from the ceiling. Not always the same place, in multiple rooms. This noise occurs throughout the day and night, particularly during windy weather. It is loud enough to wake a person, so my fiancée has to sleep with earplugs.

(As far as due diligence goes, the noise is intermittent enough to not occur for long periods at a time, and is most noticeable at night when trying to sleep, so we did not notice it until it was too late.)

Air-con is not the cause. An air-con technician has assessed the problem, and in any case the noise persisted when the air-con system as turned off from the power outlet for a week.

Roof technicians have inspected and reported no structural issues, but in their report advise it “might” be thermal expansion/contraction. I think this is almost certainly the case, based on the noises heard, when they occur, and the wooden structure above the ceiling.

Problem:

We noticed and reported the noise issue in May 2022, 14 months ago, shortly after moving in. Dealing with the building manager and strata manager were frustratingly slow. A professional roof inspection only took place in September 2022, after 4 months, and they did not inspect inside the roof.

After further slow communications for 3 months, another roof inspection took place in December 2022, again only inspecting the outside, not the outside.

After 6 months – the longest period of slow communication and inaction – another roof inspection took place in June 2023, this time inspecting inside the roof. The inspection report advises no structural problems, but that the noise “might” be thermal expansion/contraction of the roof truss.

After the above, no further action. The noise issue persists. Throughout the ordeal, my fiancée has been immediate and persistent with communications. The other parties have not.

The prolonged ordeal is extremely upsetting for my fiancée, as it is causing ongoing sleep issues and seems like an endless ordeal with no attempts to actually fix the problem.

Questions:

Are there rules about acceptable timeframes for strata to resolve problems such as these? Frankly, 14 months with no attempts to fix the problem seems unacceptable.

Can the strata be legally compelled to fix this problem? I understand the responsibility to act on issues causing structural damage or safety problems, but this is slightly outside of that.

Although the roof space above the ceiling is “common property”, can a unit owner organise their own roof cavity inspection, free of strata involvement?

In the event we simply give up and sell/rent out the unit as is: Is any party required to notify a future occupant of this issue, and could they be legally liable for not doing so? (Noting that no issues have been identified by professional inspections so far. As far as we know, the previous owner was not aware of this issue. Aside from my fiancées observations, nobody seems to think there even is an issue.)