A word of caution if you are thinking of timber framing with any unkilned hardwoods such as tulip poplar. If used untreated, powderpost beetles will probably reduce it to sawdust in less than 10 years, this is the reason that most builders do not use sawmill lumber anymore for structural frames of buildings. I have rebuilt several 10 year old barns that were collapsing because of the beetles. Spraying wood with diesel fuel takes care of it but isn't legal for some applications. Borate treatments also take care of them. Softwoods and kiln dried lumber are usually not a problem.