I am building a very energy efficient house (I hope). I am using engineered 2x4 trusses with ½” or 5/8” OSB or plywood decking. I plan on spraying the inside of the trusses with icynene or equivalent and completely sealing the attic cavity.
Here is my quandary. How to install the metal roof on the OSB to reduce heat loading even more? I have heard of nailing/screwing 2x2 wood lathing to the decking on diagonal. The metal roof sheets are then screwed to the laths, creating an air space and air flow capability from eave to ridge. Continuous ridge vents would be installed on the peaks and some type of screened treatment at the eave line of the metal roof and OSB. Where can I get technical information or personal experience on this?
Remember that the metal panels will move each time they heat up or cool down. You must allow for movement or the panels will "oil-can" meaning they will wrinkle and shift. You can go directly to the manufacturer to get clips that attach to the deck that will allow for movement and air flow. Check out Follansbee Metals in W. Va. for "fair" priced metal systems.