Hi Heidi, you should speak with your town planner to understand the zoning, height and setback allowances for the property, plus they can generally help you look into any challenges you might have with services (ie sewer, water stormwater), but depending on the site you may need further advice from a civil engineer. Either way, the town planner should be able to advise.

Armed with the info from your planner you should speak with a designer – either an architect or building designer. Many draftys also understand the planning schemes.

Costing wise, yes, speak with a builder but it can be quite a difficult question to answer. You will need to know roughly how big these units will be (something you should clarify when speaking with the architect/building designer). Other main things that effect construction price are the contours of the site (ie does it slope, which way, how much), the specification levels for your end product (there are many decisions to make here such as are you using stone benches, how thick are they, will you be having full height tiles in the bathrooms, the list goes on), size, if there will be any retaining required, extent of driveways and landscaping.

Good luck with it Heidi.