metal roofing/kiln question

[bedway]

I need some input from those who really know. Im nearing the completion of my dehum. kiln and ready to put the galvanized metal roofing on. The kiln roof is now a layer of OSB and two layers of felt paper. My intent was to install the metal right over the OSB and felt. Ive had a few inputs telling me i should put down one by material horizontally and the metal on top of those. Opinions please.

[willmyers0169]

you can do it either way, i prefer to use 1x4 stripping because it gives you more to scew to, instead of screwing directly to the OSB wich is
likely to strip causing the screw not to hold.

[Larry]

When I put metal on my new house I did some investigating.  The manufacture gave the ok to screw directly to OSB.  I also checked to see how it was actually being installed and it was screwed directly to OSB in every house I checked.  I followed suit.  A couple of years later I had a lot of screws that were backed out.  Re-torqued and they seem to be holding, but only time will tell.

I've put on a lot of roofs into solid wood and never had one screw back out.  I learned my lesson and will never ever screw directly to OSB.

[GeneWengert-WoodDoc]

It is not clear if you will also be insulating the roof, walls and floor; it is critical to do so.  A vapor barrier should also be used on the warm side.

[bedway]

It is not clear if you will also be insulating the roof, walls and floor; it is critical to do so.  A vapor barrier should also be used on the warm side.

To answer your concerns Gene, yes all walls, ceiling, and floor are insulated with the green foam and all have vapor barriers. I just need to apply the metal roofing and build the doors. Ive taken several pictures of the build and intend to post the pics. Im leaning toward putting down 1x4 nailers to screw the metal roofing to mainly do to the staement of screws not holding in OSB very well. The outside dimensions of my kiln are 12 feet long, 4 feet deep, and 6 foot tall in back with a 6 inch drop back to front.

[kelLOGg]

You'll get all sorts of bugs nesting in the cavity created by the 1x4 strips. I don't know what problems that would cause but I would be uncomfortable with it. Why will the 1x4s stay attached to the OSB and the metal won't? Consider using longer screws and screw the roofing thru the OSB to the rafters. Just my 2 cents worth.
Bob