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The Pros, Cons, and Cost of Synthetic Roof Underlayment.

Synthetic roof underlayment is a type of roofing material that protects the roofing system from the elements. It’s a primary component of any roof installation and is required by most local building codes. The purpose of underlayment is to protect the roof from moisture, wind, and other harsh weather conditions.

If you’re installing a new metal roof, you have to check the local building code to ensure what type of roof underlayment your project can use. Once you’ve determined synthetic underlayment is suitable for your project, you still have different types and brands of synthetic underlayment to choose from.


To make your buying decision easier, we go over the main types of synthetic underlayment in this article to help you choose which is best for your installation.

Mil Thickness Vs. Weight

The thickness of your synthetic roofing underlayment is important because it will determine how well it will protect your home from leaks and other damage caused by water. The thicker your material is, the more likely it will stay in place during heavy storms or high winds which can cause problems like blowing shingles or tiles off your roof.

The best way to determine if you have a high quality underlayment is by weighing it. If your synthetic underlayment weighs over 2 lbs per square foot then it’s likely that you will be getting a good product. The more weight your synthetic underlayment has, the better it will perform against fire and moisture.


Pros and Cons.



Synthetic underlayment is more lightweight than felt which makes it easier to carry and install. Synthetic underlayment also provides better traction for roofers than roofing felt in both wet and dry conditions, making it a safer product to work with during installation.


The main disadvantage of synthetic underlayments is that they cost more initially than traditional asphalt or fiberglass roofing felt products. With proper installation techniques, however, this disadvantage should not be an issue because synthetic underlayments can last up to 20 years or longer before needing replacement.

What's the Cost?

Synthetic roof underlayment is a non-adhesive mockup that is placed between the shingles and the roof sheathing. It’s also known as felt paper and can be made of either synthetic or organic materials.

The purpose of synthetic roof underlayment is to protect the roof sheathing from exposure to moisture, prevent leaks, and prolong the life of the roof.

The price of roof underlayment can vary depending on the area you live in and the brand you purchase. The following pricing is always subject to change and is only a rough estimate.

25 year non adhesive underlayment = $.15 to $.20 Per square foot

50 year non adhesive underlayment = $.20 to $.25 Per square foot

50 year self adhesive underlayment = $.55 to $.65 Per square foot

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