Insulating a steel post-and-beam house
I am using a steel post and beam building for the shell of my new home. The wall girts are on six foot centers, are 10 inches deep and have an 8 inch flange. Attached to the in side of those girts will be traditional two by four framed walls. My plan was to put 3 in of eps insulation and 7 in of blown-in cellulose behind the two by four frame wall and leave the stud cavities empty. I would use 1″ EPS furring strips between the siding and the girts. This would reduce my thermal transfer through the girts as well as producing a rainscreen of sorts. How much of a difference would there be if I put the EPS insulation in between the girts and the siding? If I do this then I have to put 10″ of cellulose behind the stud walls. It seems that 13″ of insulation is overkill.