Building a duplex can also reduce the cost per dwelling compared to constructing two separate houses. By sharing infrastructure such as walls, plumbing and roofing, you save on materials and labour costs.
You can also leverage the economies of scale, by using one building designer, one builder and one set of subcontractors, as well as one set of plans for approval. The best duplex builders in Sydney give you a whole package deal, for a fixed price, which includes a feasibility report, designs, approvals, construction and more.