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I am building a 40x50 garage 12 foot sidewalls 2x6 framing with osb on all sides wraped with tyvek. the roof are trusses with 2x4 perlins 24'' CENTERS. the whole building will be covered with pole barn metal 26ga. the whole interier will be metal also. the building will be heated and cooled with 6''batt insulation in walls and18'' blowen on top of metal ceiling my question is do i need a vapor barrer under my metal roofing. is the tyvek ok for all sidewalls. thank you in advance for any help mike
9/29/2019
Or copy this URL: https://www.metalroofing.com/spirit/comment/24475/find/Tyvek is a house wrap that is not intended for roof application. I believe that they have a sister product for roof underlayment. I would also suggest a vapor barrier on the inside of your insulation.
Isaiah Industries, Inc.
9/29/2019
Or copy this URL: https://www.metalroofing.com/spirit/comment/24477/find/todd are you saying to skip the tyvek on the sidewalls and put the vapor barrier on the inside
9/29/2019
Or copy this URL: https://www.metalroofing.com/spirit/comment/24478/find/Tyvek is not a vapor barrier. It is a breathable house wrap. There are similar roof underlayment, but they breathe mainly just through the laps and seams. I would use house wrap such as Tyvek on the walls, synthetic underlayment on the roof ... and then a vapor barrier on the inside. A vapor barrier is typically a heavy sheet of polyethylene with taped seams.
Isaiah Industries, Inc.
9/29/2019
Or copy this URL: https://www.metalroofing.com/spirit/comment/24479/find/+1. The roofing underlayment (if you use a synthetic) is a vapor control layer.
Is the roof going to be vented here if you are blowing in 18" of insulation. Sounds like you are going with a vented style attic.
Do a bit of air sealing on the attic floor, and she will work like a dream.
An informed customer is the Best Customer!
9/30/2019
Or copy this URL: https://www.metalroofing.com/spirit/comment/24480/find/