Furring Strips On Roof Deck?

Hi everyone, I am in the process of shopping for a new roof and I would like to install a standing seam metal panels. However my home was built in 1925 and over time the 2x6 rafters (17 ft span) have sagged in the middle. There aren't any split/snapped rafters or other structural damage to the roof, but I worry that it would be impossible to make an adequately in plane roof deck for metal panels. I have spoken to some local carpenters and roofers (Western North Carolina) and their suggestions have ranged from a complete roof rebuild, to shimmed furring strips, to choosing asphalt shingles instead. My question is: could furring strips provide an adequate substrate and plane surface for attaching snap lock standing seam roofing panels and if so what would an appropriate design/pattern look like. I welcome all questions and suggestions. Please let me know if there is additional information needed. Thanks all!		Guest User 10/8/2016	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/21567/find/
Purlins, done properly, could work. I would still prefer a solid deck for the moisture and condensation prevention benefits as well.		Eric Novotny An informed customer is the Best Customer! 10/8/2016	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/21568/find/
Thanks for your reply Eric. Would pressure treated purlins (seperated from the roof panels by some membrane) and a proper underayment help prevent condensation issues? I also plan on adding a ridge vent, athough I have heard different opinions on whether or not this will help with condensation issues especially in my climate. Thanks again.		Guest User 10/8/2016	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/21569/find/
In theory...yes. In practice, much more difficult to get sealed up and known to be problematic. By the way, you don't need PT in this case. Even venting the attic, I would still go solid decking. Spend the money and do it right. If you do, you will never change out the roof again and you will be happy with it.		Eric Novotny An informed customer is the Best Customer! 10/8/2016	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/21570/find/

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