5V crimp metal roof underlayment question

ugabulldog

I am building a detached garage with a 6:12 roof pitch. 2" x 6" rafters 16" OC. I was planning on running 1" x 4" purlins every 2 feet and putting a 5 V crimp metal roof on (26 gauge). The metal I was looking at is from Metalsales and according to them, 5 V should only be installed over solid substrate. Is this only for snow loads? I live in South Carolina. Also, I was going to install the purlins this weekend, will this be ok for code or should I call Mon morning and make sure it doesn't have to be 2" x 4" purlins? thanks

OldNBroken

I'd have to dust off my MetalSales spec book to make sure but pole-builders put garbage 29ga rolled rib over perlins all the time so I don't see why 5v wouldn't be fine over 1x4 batts @ 2'. 26ga 5v is a sturdier product than the above (about the only thing it's better than) so, in my opinion, I don't see a problem.

If you are worried about MetalSales warranty this product...:n o:

Sorry, not a big fan of MS.

Personally, I would not put anything that was not mechanically seamed over any open span. Any snap lock or lap joint panel actually should be put over solid decking mainly because any weight on the spanned area will stress and weaken either one of these joints. But, like I said, I see pole builders doing it every day.