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Advantages of synthetic versus felt under metal roofing
| By Jan Furgason, TFC Farm Hardware Product Manager |
8/1/2012 |
Felt has been around for as long as anyone can remember and has served its purpose well in the construction industry as the most widely used roofing underlayment. But as building codes are continually changed and challenged, products must improve and perform for the long haul.
Until the 21st century, most residential sloped roofs received a layer of asphalt-saturated felt building paper underneath the roofing material. But today’s felt is not the same as what your grandfather used, and the need for a tougher, stronger, and longer-lasting roof underlayment has never been greater. Most builders and homeowners will agree that a traditional 30-pound felt is not the best solution for an enduring metal roofing project, but synthetic underlayments may cost a little more. Are they worth it?
Because it prevents the ingress of moisture into the sheathing and roof structure, the underlayment is an extremely important aspect of a roofing system. Synthetic underlayments like PermaFelt offer superior strength and lighter weight as compared to traditional felts, resulting in less waste and faster installations. In addition, they can be left exposed for longer periods of time — up to six months if necessary — without compromising their integrity. Saturated felt can be exposed for only a few days and can potentially blow off or, once exposed, might not prevent water entry that could arise from high winds and rain, causing catastrophic damage.
Synthetic underlayments are are also skid-resistant and provide a superior walking surface in both wet and dry conditions. They do a much better job of staying on the roof and protecting it from the elements. Their resistance to wind, ultraviolet light, and long-term moisture is far superior to felt.
Synthetic underlayment was specifically designed for metal roofing applications although it is also suitable for use with other roofing materials that do not involve hot asphalt or coal-tar pitch. Felts will dry out and crack over time, thus compromising their capabilities as a waterproofing underlayment. This process is accelerated by heat, and because temperatures can soar beneath metal, this becomes an even greater problem for metal roofing applications. Synthetic underlayments are resistant to high temperatures, which keeps them from drying, cracking, softening or melting and sticking to the underside of the metal roofing panel. This eliminates the need for a liner sheet, allowing the metal to expand and contract freely.
And unlike asphaltic felts, synthetic underlayments do not leech oils or emit fumes, making them more environmentally friendly.
Moving from felt paper to a synthetic underlayment is a very small fraction of the overall roof cost but delivers vastly superior performance. When you install a metal roof, you are making an investment above conventional roofing products. A premium underlayment is your best choice to enhance the performance and longevity of your project.
For more information, visit http://www.permarproducts.com/permafelt.html.
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