What are the four main types of construction contracts used in Australia?

What are four main types of construction contracts used in Australia include lump sum, cost plus, design and construct, and construction management contracts. Four main types of construction contracts used in Australia, which is building industry with standards including AS 4000, AS 4901, and ABIC contracts, include lump sum contract, also called fixed price contract, where contractor agrees to complete project for fixed price with detailed drawings and specifications, common for residential building under HIA and MBA contracts, with risk on contractor for cost overruns, and cost plus contract, where client pays actual construction costs plus agreed margin, typically 15 to 20 percent for contractor overhead and profit, used when scope not fully defined, and design and construct contract, also called D&C, where contractor responsible for both design and construction, offering single point of responsibility, common for commercial projects, with contractor managing design team and construction, and construction management contract, where client engages construction manager to manage trade contractors on behalf of client, with client holding trade contracts, used for large projects. Another classification includes major works contracts under AS 4000 and minor works under AS 4905. So four main types of construction contracts in Australia are lump sum fixed price, cost plus with costs plus margin, design and construct with single responsibility for design and build, and construction management with manager managing trades, with lump sum most common for residential under HIA contracts.