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Best practice for roofing/insulation without a ridge vent?

This_guy | Posted in General Questions on

Hello all,

New user here. Zone 4A. Looking to actually build a “tiny house” of sorts out of a portable building. I’ve been looking for information on the best way to insulate a roof that will not have a ridge vent.

The portable building has a metal roof over osb with a barrier in between. We’re looking to insulate and face with drywall. I have read that humidity will make rot an eventual problem in this situation.

Do you have any suggestions? Sorry for the dearth of details but I’m not exactly sure what I’m doing, hench the questions. Thank you for your time.


Ray D.

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  1. GBA Editor
    Martin Holladay | | #1

    Here is a link to an article that should answer all of your questions: How to Build an Insulated Cathedral Ceiling.

    If you were willing to temporarily remove the roofing so that you could install one or more layers of rigid foam above the roof sheathing, or if you were willing to retrofit a ridge vent, you would have lots of options.

    But if you insist that (a) you cannot temporarily remove the roofing, and (b) you cannot retrofit a ridge vent, then the answer is fairly simple: you have to insulate this type of roof assembly with spray polyurethane foam.

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