Underlayment Material for Your Metal Roofing System

Underlayment Material for Your Metal Roofing System

Underlayment Material for Your Metal Roofing System
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Underlayment products for a metal roofing project to be used beneath the seam should be carefully selected in order to provide optimal longevity of the building. You should take several considerations before you decide the roofing system design including the four barriers needed and these are the vapor retarder, air barrier, thermal insulation and water barrier. All these are needed to be placed in the right location for any given season.

The longevity of service can be affected by these factors. Therefore, your metal roofing contractor must be able to determine the roofing system itself, the possible climate within that particular area, the roof slop and geometry of the building. Improper selection of metal roof underlayment can lead into roof leakage and also it may be able to entrap the moisture because of the vapor diffusion or possibly air exfiltration. These factors may affect the quality of the roof that may deteriorate the metal materials which you may need to make necessitating repairs which are pretty much expensive.

Metal roof panel

The metal roof panel are intended and designed to span structural support. Yet, these supports do not include underlayment since the structure has substrate or deck to support the material. For architectural metal roofing, an underlayment is indeed a must in order to help control water leakage through the roofing system especially if there are numerous heavy rains or snows which are eventually melting before the spring.


Top notch underlayment is often designed in cold climates in order to protect the roofing system under ice dam leakage. While on the other hand, there are underlayment which are specified in a high temperature where the in-service can handle the as high as 240 degrees.

Traditional Underlayment

Most common materials for underlayment on a steep-lop metal roofing system is the non-perforated asphalt underlayment. Several types are available and these are the organic and inorganic reinforced underlayment. The design will depend on the local building or the architectural designs.

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Metal Roofing System

Synthetic sheet underlayment

These underlayment are made often made from polyethylene, polyolefin or polypropylene which are all made from plastic. These types of underlayment are less susceptible to wind damage and less sensitive to cold weather. The most common synthetic sheets underlayment sold in most part of metal roof Virginia are the vapor resistant.

Self-adhering Membrane Underlayment

This type of underlayment is typically impermeable for vapor to the substrate in order to get adjacent sheets from side to side. This is particularly designed to resist air pressure and serves as an energy efficient ventilation system air barrier material. This is commonly consisted of rubberized asphalt or butyl based adhesive with polyethylene sheets.

Alpha Rain Incorporated

Now that you understand the different types of underlayment sheets to be used in your metal roofing. You can finally determine what type of underlayment you’ll need for your metal roofing upgrades. Of course, just to make sure, consulting with the experts or with your metal roofing contractor will help you to decide for your underlayment. Choose Alpha Rain Incorporated, makers of patented roof ventilation system powered by Therma-Vent.

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