All wood species which are used for traditional timber framing are green woods: green-oak is a term I think most people have heard. It simply means that the trees have been felled quite recently- within weeks or a few months- and have not seasoned, or dried fully- a process which occurs slowly and naturally as the moisture in the wood is lost by evaporation. Oak, Larch and Douglas Fir are worked and assembled green because they can be worked efficiently and accurately and the Greenwood is kind on the cutting edges of chains and blades. Once your frame is raised the wood seasons over time and leaves you with an incredibly strong and beautiful structure.