How do I insure myself for renovation risk?

I live in NSW.

With the new laws since Nov 2016, (but I think that for some major changes, even previously), a lot owner have to have a by-law written, in which they take upon themselves all responsibility (hence a risk) for any damages that may be caused immediately or may occur in later years due to their renovation (for major changes, like wall removal for example).

We have been looking at removing a load bearing wall (all walls in the unit are load bearing). We got the engineer report ($500) and quotes for the job at around $4000. So all and all less than $5000.

Though we would like to hope that the engineer calculated it all right and it will all be very stable, and the builder will do his work in the most professional way, there is always a risk for damages, and even maybe a collapse of a building when removing load bearing walls, so since we get the responsibility in the new by-law, we were looking how can we insure ourselves for this risk. As a lot owner we are not aware we can take any such building insurance. Please advise if you know of any, and to what amount do we take cover? a whole building worth? That would be a huge cost for a single lot to do, but is the only cover protecting from a building collapse risk.

When we asked the Strata manager about what seemed to us as a flaw in these new laws, we were told that the insurance of the builder and engineer would cover the risk, HOWEVER, we understand that:

1. for jobs less than $5000 (regardless of what the cost of damages can be) the builder doesn’t even have to have insurance

2. just like with car insurance, I don’t like to rely on someone else’s insurance for my risks. I’d rather have my insurance, and if my insurance thinks they can get what they paid out of the builder, let them chase him. I can see cases where the builder folds to avoid payment and then the owner is left with the bill and no insurance cover if they rely on builder’s insurance.

3. the cover/warranty they need to give, to my understanding, is up to 6 years, but the by-law I have to write, and the responsibility and risk that come with it is for the rest of the life of the building. What if cracks will appear in year 8?

4. From one builder’s insurance cover that I saw, his cover was up to $2 mil, hence would be ok for most issues, except the worse case scenario of say a building collapse, or part of. That requires (as per our strata insurance) quite a few more millions in the cover, and I doubt many (small job) builders have such insurance. The renovation will exclude my unit from the Strata Building insurance cover for all things to do with the wall removal.

Our unit is in a small block, and it is quite popular to renovate units to be open spaces by removing walls. If eventually every unit will do something like this, and each has to write a by-law excluding it from the Strata’s building insurance (or damages that can be linked to the renovations will be excluded but that can cover a lot of areas) it make you wonder what will the Strata’s building insurance be left to cover?