To get idea of costs you need to start with local architect. It will depend on local trade costs your site costs, the extent of renovation you want to do - eg new kitchen, as well as size of addition. Could be 400k could be 700k. With this option I have avoided bringing plumbing over garage to get a bathroom between bedrooms. Given larger dining space and made smallest bedroom a bit larger by moving robe into existing master.. all the little changes such as doorways and robe changes add costs with floooring etc.

I have evened up the bedrooms and added storage to entry hall and dining a bit bigger with dual access

Thanks Kate - super helpful. So, do you think the redesigned floor plans you’ve suggested could be achieved within the 700k range (include an extension for a master)?

I would work out how many square metres you are adding and renovating. Then times that by $5000 per square metre. But there are so many variables. What is the house made of, brick or timber, what is the roof line to be able to be adaptable for an extension? Are the floors concrete or wood, to accommodate changes in plumbing? What specifications are you after, low, middle range, or fancy? Is the land flat, do trucks have good access…..?? Etc etc. only a few years ago I would have had said $3000 per square metre, but now…you need good firm quotes….and good firm time lines….so that is why I have said a very unsure $5000 per square metre.