Vic building costs ?

G'day all,

I'm about to arrange insurance for a IP recently purchased.
Apart from trying to find the best landlord cover, calculating the building costs for the house is proving to be more confusing than I had initially expected.

I'm talking about a brick veneer of good quality in Melbourne.
The CBA suggests $1,235 per sqm.
The ANZ uses $600 --> $1,000 per sqm, generally $860.
The National uses something close to $900 per sqm.

How can there be so much variation ?
What figure are others using ?
Is there a site which updates these figures for all to use ?
Why is the CBA figure so high, aprox 26% above others ?
You can start by looking at what new housing costs to build these days, and then start increasing the price based on things your house contains that a new one might not.

For example, most "big" houses you buy new these days are "boxes" so you pay less per square for these types of designs. If your house has a complex design, complex roof structure etc, it's gonna cost more.

If you house has special internal doors (eg. cedar, leadlight, etc), decorative cornice, ceiling roses etc, all that will add cost to reconstruction. Granite kitchens, stainless steel appliances, polished floors (esp if timber like jarrah etc) all add to the price.

Can a quantity surveyor calculate cost of rebuilding?

An alternative strategy might be to use your rates notice, which should show capital improved (house/land) and unimproved (land only) values. Subtract one from the other is their value of the house. Add perhaps 20-40% to get a potential rebuilding cost?
Rawlinson's Cost Guide says

Excluding GST,

Project house B/V
Basic standard finish $725-765
Medium standard finish $810-865

Individual house B/V
Medium standard finish $965-1025

Currently it is costing us between $800 and $900 per sq mt to construct townhouses around Melbourne. And even up to $1,500 for classy ones in Richmond.
You also have to remember that there are other costs involved like architects, plans and building permits if you have to build or rebuild