allseason Thanks for the reply, unfortunately I just noticed the issue this morning on the way out. Job was finished yesterday but was it dark when I got home. I'll may post pics when I get home. The underside of the roof are 1x4's, painted. Not sure if there is another layer between the 1x4s and the shingle until I get up there and take a look Chad and Jim, Thanks for the info guys, I agree 3/4" would have been the better way to go, but I guess not the cost effective one on their part.