Thanx for advice in advance ! I'm building a roof over trailer-home to improve insulation and snow runoff. If you've done such a project what do you recommend for best insulation and frame design to go with that? Basically I am doing concrete 'post holes' with steel post & welded saddle:beam along-side the trailer on posts and stick framed rafters on that, beams "tied" together with 2x4 purlins over trailer roof(possibly just above solid polyiso. insulation laid on existing roof).