[karoc524]

Guys this is a new construction question,building with trusses that have a 4/12 pitch and looking for suggestions for the decking.OSB is my first choice since its cheaper but I see that Zip Sheathing is the new way for decking but that's 20.00 sheet. Another area I am wondering about is the underlayment,which one is best for this hot and humid climate that I live in which is Tx. What will help deal with condensation,I have read so much on condensation developing under the metal roof. The metal has a 40 yr warranty so I don't know if the underlayment has an age limit or not. Looking for suggestions on how to deal with condensation since this is also going to be my home. Any links or Youtubes on any of these issues and open for suggestions and direction for products that you use.
Oh I know that spray foam is the go to now days but what is another choice

 

[rjniles]

You need a water proof membrane under the metal. You could do that with Zip sheathing. I would use ice and water shield.

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[u2slow]

OSB sags and swells with humidity. I was rather disgusted with it when I re-roofed my bedroom/bath addition. I would use exterior grade plywood.