What is the Best Underlayment for Metal Roofs?

An underlayment is crafted to sit beneath metal roofing, providing thermal protection and weatherproofing for your property. Without the use of an underlayment a metal roof can be extremely loud whenever the rain starts to pour, uncomfortably frosty through the winter months and unbearably warm in the summer, so there’s really no questioning the fact that your metal roof will benefit from the addition of underlayment. However, there are 3 main materials that work well when crafting quality underlayment, and it’s vital that you can find out which is the best style for your specific metal roofing needs. So, what are your options, and which of these should you choose to get the most out of your metal roof underlayment? 

Felt Underlayment 

Felt underlayment is referred to using several different names, including felt paper, roofing tar paper and the more complex chemical name, asphalt-soaked felt. Felt underlayment is likely to be the most common style of metal roof underlayment material used on heavily sloping roofs, making it readily accessible as an easy-to-purchase addition. It’s generally more affordable compared with other styles of underlayment, and it’s super water resistant meaning water is unlikely to penetrate the roof even under harsh weather conditions. Unfortunately there are several disadvantages, such as it’s generally short life span and it’s unsuitability for hot environments. To add to this, the materials used in felt underlayment are not widely recycled, so a large amount of waste product is left when your roof requires an update. 

Synthetic Sheet Underlayment 

Synthetic sheet underlayment is a more modern style which has taken the industry by storm over the last decade. Synthetic sheet underlayment is created by the combination of polyethylene (or polypropylene) and some kind of polymer in order to make a strong protective barrier between the metal roof and the underlayment. It has a considerably longer life when compared with felt underlayment, as it’s much more durable due to the thermoplastic polymers which are resistant to many kinds of damage. In addition, synthetic sheet underlayment functions well in hotter environments, so locations that receive a large amount of sunshine can benefit from the installation of such an underlayment. However, synthetic sheet usually comes with a much higher price tag when compared with felt underlayment, and although it benefits from a low permeability rating, this factor will mean that it’s difficult to achieve good ventilation.

Self Adhering Membrane Underlayment

The complex sounding self adhering membrane underlayment is actually a lot more simple than it sounds, as it is in fact a kind of ‘peel off and stick down’ style that’s made up of a form of rubberized asphalt (or sometimes butyl based adhesive) that is partnered with a polyethylene carrier sheet. Self adhering membrane underlayment works well to prevent ice dam build up in areas such as the eaves, but it can also provide protection for hotter environments which see temperatures of more than 230 degrees. SAM underlayment is an efficient air barrier material as it fits completely flush with the surface of substrate. Always ensure you seek an experienced installations expert when utilizing self adhering membrane underlayment, as you may encounter peeling if you fail to attach the underlayment correctly.

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RPS Metal Roofing & Siding, Inc is a manufacturer and distributor of metal roofs. Located in Welaka, Florida, our company has state-of-the-art manufacturing equipment resulting in fine quality metal roofs for commercial, residential and agricultural use.

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