Andy Edge
11/2/2016
I will be removing an old cedar shake shingled roof and installing a new black in color metal roof. The roof is on a residential home in eastern NC. The home has attic space between the living area and roof deck except for the living room area which has a cathedral ceiling. The shingles will be removed and a solid plywood deck will be remaining. My questions are as follows: 1. Is it better to install on top of the plywood the underlayment then the metal panels or underlayment, furring strips, then metal panels? 2. 26ga or 29ga? Does it matter? 3. Should anything be done differently over the cathedral ceiling? I thank you greatly for any advice and information.
Todd Miller
Isaiah Industries, Inc.
11/2/2016
Thanks for your email. Here's a link to a video I have put out on the battens question: https://www.youtube.com/watch?v=pEWcwNg29Ag Fact is, in your case, you are dramatically changing the breathability of your home going from wood shakes on lathe to solid decking. If you can have good ventilation in the attic, I do not think battens play a role for you. However, they may be a good idea over the cathedral area. Keep in mind that proper attic ventilation requires intake and exhaust vents. A great source of venting information is available at www.airvent.com As far as gauge ... certainly I can build a case that heavier gauge is ultimately better but I'd prefer to see you focus on a quality coating, a good manufacturer with a good warranty, and proper installation. To me, those are more critical than the metal thickness.
Andy Edge
11/2/2016
Thank you for the quick response. The current roof does in fact have solid decking in the form of plywood. The attic is ventilated through soffits to gable vents. When we place the new roof on we will add ridge vents to ensure that ventilation through the attic is proper. I did watch your video and from your answer, I see that I can do without the battens except for the cathedral ceiling area. That area does concern me with ventilation.
Todd Miller
Isaiah Industries, Inc.
11/2/2016
If you add a ridge vent, assuming you have a clear air pathway from the eave soffits to the ridge, I would encourage you to close off the gable vents. They will disrupt the natural convective airflow and short circuit it.
Andy Edge
11/2/2016
We will be installing the soffit baffles to ensure the air is not blocked by any insulation in the attic. I will also close off the gable vents with the addition of the ridge vent. Thank you for your help and information.

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