Underlayment for Metal Roof and the Material Types

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Underlayment is a layer that put underneath metal roof as the waterproofing method, as well as thermal protection for a building. It is considered as important, as metal roof can be extremely hot on summer days due to high temperatures, cold during season of winter and loud during rainy weather.

However, choosing underlayment for metal roof is a matter of its own. Read and learn how to pick the best and suitable material for it in the following.

Best Underlayment for Metal Roof

You might have wondered, what do you put under a metal roof? The answer is underlayment, which is consisted of waterproof or vapor barrier material. This piece is installed on the decking of roof system directly to combat extreme weather and climate circumstances.

Underlayment for Metal Roof

If you aren’t using underlayment for metal roof, there’s a chance of roofing system and the rest of building of being exposed to elements such as moisture, wind, resin, or chemical.

Read also : Metal Roof Underlayment

Selecting the best underlayment is important to maintain the lifespan of your home. There are three underlayment types that most commonly available, that you can read about below:

Felt underlayment

This type of underlayment might be referred by different names such as asphalt felt, roofing tar paper, or felt paper. Compared to the other two, it is the most used material type, because it is easy to find almost everywhere and is more affordable amongst them.

Synthetic sheet underlayment

The second underlayment material is relatively new, but has gained popularity in its respective industry recently. Synthetic sheet is a protective barrier that made by spinning or weaving polypropylene or polyethylene together with polymer. Compared to felt material, it is more expensive but has better durability.

Self-adhering membrane underlayment

The last material of underlayment is the self-adhering membrane, which is the type of peel-and-stick item that’s being adhered to roof deck. It’s considered as the most suitable for high temperature underlayment for metal roof, because it can resist temperature up to 240ºF.

However, it might perform rather poorly on low temperature.

Synthetic Underlayment for Metal Roof

As it has been mentioned in prior, synthetic underlayment is a newly innovated material that’s currently taking the industry over. This protective sheet layer is considered as favorable underlayment for metal roof because of its qualities. Here are the advantages and disadvantages of using this material:

Synthetic Underlayment for Metal Roof


There are many homeowners that choose to use synthetic sheet because:

  • It generally has better durability compared to felt underlayment
  • It has higher resistant to various types of damage, moving, or tearing because it is created with thermoplastic polymers
  • It has quite of a good tolerance for extreme temperatures


The downsides of using synthetic sheet underlayment for metal roof are:

  • It is pricier compared to felt underlayment
  • It has low rating or permeability, so it is not the best material to have proper ventilation, but otherwise is great to combat moisture.

Is Underlayment Necessary for Metal Roof

Metal is definitely a durable material for roofing system. In fact, they can last up to 70 years. Its resistance to weather such as blizzards or rainstorms, and its excellent durability are part of why it is commonly used all around the world.

However, it still needs to be taken care of to last as long as it should. If you still wonder if adding underlayment for metal roof is necessary, then the answer is, yes! Underlayment is highly recommended to be added to metal roofing.

There are a lot of potential issues if you choose to go without it, such as roof leakage, trapped moisture, and other problem assortment that might deteriorate the quality of your roofing system, as well as reducing the metal roofing’s longevity in the future years to come.