Apologies Michael, fair enough, I will do my best.
"Give sizes, dimensions, materials (existing and proposed)"
The house is brick and tile. I am pretty sure it is footing on concrete slab. Currently the house is high set, about 7 foot clearance below. I would say the upstairs current space would be approximately 80sqm (not sure if that helps with the roof),
"type of construction (existing and proposed)"
brick veneer and tile, I will render and paint (not fan of cracked oxided cement)
and anticipated before and after values (asking price and guestimate will do).
$250k asking, I am thinking around $400k after the new space and render. However this is dependant on the Brissy market and how people feel about views. Views dont seem to be getting the full premium here in some areas. Having grown up elsewhere and seen how that changes with supply and demand, it might have to be a case of holding on for a while. Which is fine as this property is mostly PPOR.
"Furthermore $100k to some is a major expense, to others it is loose change (seriously)."
$100k is a figure I dont have right now, but hope to fund in the future. So $100k would be my maximum expenditure. Some of these variables are hard to answer as the project is hypothetical until its a reality (purchased).
The main concept for me now is to get a figure in my head of the kind of requirements, costs and benefits of these projects, not just for a house Im looking at buying now, but as a style of reno for future investments.
Hope thats of some use.