We are using RoofTopGuard II High Performance Roofing Underlayment. How does this compare with felt as relates to indoor air quality?

Asked by Susan Mayne
San Rafael, CA

Using Monier lightweight tile. The underlayment is one of their products.


Danny Kelly

Answered by Danny Kelly

Charlotte, NC

Kelly McArdle Construction

August 20, 2010

The RoofTopGuard product should be fine and really should not have anything to do with your indoor air quality.

  • I assume you are using plywood or OSB as your roof decking.
  • Just be sure you have a properly vented roof.  The RoofTopGuard product is a vapor barrier, so any hot air escaping from your home into your attic during the winter will not be able to diffuse through this product.
  • If you do not have proper ventilation, the result will be moisture condensing on the roof decking and not being able to escape, causing mold and rot.

If your roof is properly ventilated, any moisture that enters will be able to escape through the vents.

Tagged In: home air quality, roofing, attic ventilation

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