Hello,
I am reading Ted Benson's The Timber-Frame Home and on page 99 he describes the horizontal nailer system for walls. At the end of the paragraph he states that his shop was built using a variation of this system, using furring strips for nailers with 1" thick EPS between them. The interior and exterior finishes are vertical boards. My question is , do you need sheathing before applying the exterior finish (vertical siding) , or can you attach the siding directly to the 2x4 nailers?
Thank you
Ian

You could attach directly, but it's really a question of whether or not you need the shear value of sheathing. 1" foam is a pretty negligible amount of insulation, especially with all of the thermal breaks from the strapping. I would absolutely put some kind of drainage plane behind the siding (tar paper, Tyvek).

here's what worked well for me..
http://forums.tfguild.net/ubbthreads.php?ubb=showflat&Number=22170&nt=3&page=1
Look into the plank method mentioned by Timbeal. Pretty sure it would save a lot of wood, it was my first choice, but had to go with what made the officials more comfortable
Having those empty 2x cavities on the outside of TF made running wires a breeze though....

A few choices for wiring, interior walls, chase boxes in various locations, conduit, outside in the strapping bay, eve soffit boxes, in the floor system if it is common joist built, wireless technology..... it does take a little more effort, but possible.