What is the tributary joist & bearer span?
The tributary area is a loaded area that contributes to the load on the member supporting that area. On the Prolam Specifier under each non-bracing calculator, the diagram shows how to calculate this.
Where is the bracing posts chart on the Specifier?
Under http://specifier.prolamnz.com/resources refer to the document 'Prolam Bracing Posts'
Should I go by absolute deflection or residual deflection?
Depending on the allowance for deflection below the horizontal line, the residual deflection is long term deflection below horizontal after pre-camber and is the recommended value for typical designs. The 'absolute deflection' is the maximum beam movement. After selecting 'calculate' these notes are located below the list of products that suit the design.