Amount of labour needed
To be able to calculate labour quantities you need a general understanding of the construction process. You can get this information from discussions and texts, but it is largely learned from actual experience.
Trade knowledge and trade estimating books such as Rawlinsons Australian Construction Handbook and Cordell's Building Cost Guide Rawlinsons Australian Construction Handbook and Cordell's Building Cost Guide are building industry reference books which provide lists of average costs for labour and materials required in building projects. mean that labour times for most activities can be estimated using established knowledge. Naturally these times will vary with the experience of the tradesperson, but an average figure is used for estimating purposes.