There are several factors that can affect a construction cost significantly, hence your budget. Some of which are as follows: Slope of the site; Suburb or location of the site; Ground and foundation conditions; Demolition and clearing the site; Council requirements or development control legislation; Availability of services to the site; Size of the project; Quality of fit-outs, finishes, and fixtures; Repetition or simplicity in design; Comprehensiveness if building design documents; Economy and market forces; Method of construction; Conditions of contract. Once an architect helpsย prepare a building design concept for you, it is best to have a preliminary construction cost.