Over 4.6% of the average house building cost is in the Roof trusses. Roof trusses, Pre Fab. Wall Frames & Floor Trusses are fabricated in factories and delivered to site usually by crane truck. Selected truss manufacturers can supply the labour to supply and fit the frame of the construction. Roof trusses can be constructed at an external factory prior to the walls being erected or they can be site measured depending upon the builder. For all your Timber & Hardware enquiries contact the following national and regional suppliers.