In residential construction the word addition means to go up and not out like an extension does. Going up means you will give your home more living space, without giving up any of your yard. In other words, when you have an addition done to your home you will gain another floor level, adding height rather than length.
The design for your addition should ideally be driven by your budget, in turn this should give you a good guide of the overall project cost. In our experience a quality architectural build will likely fall between $3000-$5000 thousand per square meter depending on the construction type, and level of finishes.
When thinking about duration, there are a number of factors that influence construction time frames such as the level of detail in the design, how thorough the documentation is and of course the size of the project, although a general feel on an addition falls between 3-6 months.
Some factors to consider when thinking about a first and second storey addition are council approvals. Does your land size, street, or area allow additions and what are your councils’ requirements?