Underlayment or Not? | Todd Miller

Underlayment or Not?

June 9, 2009 | Filed under: Misc, Roofing Answers, Roofing Installation

Craig asks:
Q: Hi, I’m considering replacing the roof on my hunting camp with new tin. I was curious what to put under the tin as a underlayment. I believe there is tar paper now however someone told me I didn’t need an underlay and could just fasten it directly to to the boards. This camp is an old log style built in the 20’s with a board roof. It is heated by wood stove, and only used 3-4 times per year. Any advice you have would be great.

My answer:
A: Good question. The potential issue here is that metal conducts cold pretty easily. If I understand your exact construction, this could pose a problem by creating a situation where warm moist air inside the cabin could condense.

I would suggest trying to add a vapor barrier someplace underneath the roof and at the very least I encourage underlayment beneath the roofing. I would suggest one of the newer synthetic underlayments such as RoofAquaGuard or Titanium. There are many others as well.

You may also want to consider a layer of rigid insulation beneath the roofing. Make sure that the roof you choose is suitable and approved by its manufacturer for this type of application.

todd Miller

has spent his entire career in the metal building products manufacturing industry. He is president of Isaiah Industries, an organization recognized as one of the world’s leading metal roofing manufacturers. Todd is currently Vice President of the MRA (Metal Roofing Association) and a Past Chair of MCA (Metal Construction Association). Through his website, he strives to raise the bar on standards and practices to provide property owners with the best possible products for successful roofing projects.

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