do you need sheathing underneath metal roofing?

Guest User
10/5/2011
Just wondering, I recently put an offer on a house and during the inspection we found that the roof is just metal with no sheathing. There is a barrier between the sheet rock and insulation and the electrical components have a cap on them. I want to know if this is common practice, thanks
Todd Miller
Classic Products, Inc.
10/6/2011
This is a practice that probably meets code as well as manufacturer specification. There are metal roofs which can be installed in battens only without decking. However, as a matter of practice and for several reasons, I personally never suggest doing this on a residential roof.
Info @windowsonwashington.net
An informed customer is our best customer.
10/6/2011
+1 Permissible by many codes, but definitely not preferable in my world.
michael lent
7/15/2014
Why is this a bad practice? It seems to me that the lack of permeability of metal roofing would be at least partially mitigated by spacing the roof above the decking by an inch or so. The practice of using membranes in leu of sheathing is coming into use now in advanced construction, and to be able to use a metal roof over the membrane material would be great, but the metal would have to be spaced above the membrane in order to provide for sufficient air movement to ventilate any vapor permitting the membrane construction.
Info @windowsonwashington.net
An informed customer is our best customer.
7/17/2014
Noise, walkability, levelness of the deck, permeability and condensation issues are just a few of the issues that can creep up.

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