Understanding Roof Underlayment Types: Choosing the Right Option

At first glance, most people think a roof is just one part, be it shingles, metal panels, or tiles. However, roofs come with several parts, many of which are detrimental to keeping your house weather-resistant. One of the most lesser-talked-about ones is the underlay. So, what are the types of roof underlayment, and which one’s the best for your roof?

Roof underlayment is considered one of the vital pieces of a roof. It’s a form of barrier that not only keeps your house dry but also supports the top part of your roof. So, it’s fitting that we cover some of the basics of roof underlay!

Today, we’ll look at what underlayment is and what the best roofing underlayment options are for your specific roof type. Plus, we’ll check out how to choose the right one for your roof based on a few factors.

Types of Roof Underlayment

What Is Underlayment

Think of a roof underfelt as a t-shirt for your house. The top part of your roof is the jacket that will keep you warm and dry, but the underlay ensures that no drop of water seeps into your house.

Going off of this example, the roofing underlay is located between the top part of the roof and the decking. If a shingle flies off of your roof, it’s the underlay that will keep your roof decking dry. You can choose from several roofing paper types, which we’ll cover right below.

Types of Roof Underlayment

With it being a pretty important part of a roof, there’s a small variety of options when it comes to choosing underlay. The three that we use in our SoCal base are the following:


Felt, also known as asphalt-saturated felt or tar paper, is the most widely used type of roof underlay. Even though it’s not the most durable one, it comes at a much more affordable price than the rest and lasts about as much as an asphalt shingle roof.

Roofing felt isn’t fully waterproof, but it is water-resistant. However, one of its issues is that it can tear easily, which can be destructive considering that parts of the felt might be left exposed for weeks or even months. Still, it comes in two different subtypes, namely #15 and #30, which translates to 15 and 30 pounds of felt per 100 square feet, respectively.


Let’s take it up a notch with rubberized asphalt underlayment. This type is also known as self-adhered underlay, as it comes in a peel-and-stick form. Simply put, this is the best type of roofing underlay you can get, for it is fully waterproof and very durable.

This does come at a premium, though, with it being the most expensive option. That said, its self-adhering properties mean that the installation process will be sorter; plus, due to its composition, it’s also self-healing, adding to its durability.


Even though it’s not the absolute best, synthetic roofing membranes are our favorite type to use, especially under metal roofs. This is the new kid on the block, as it was introduced in the market in the late 90s-early 2000s.

It’s not as waterproof as rubberized underlay but has much better tear and mold resistance. In turn, it’s more effective against the elements and more lightweight than the other types. While it does have its drawbacks, like its cost, synthetic underlayment is by far the best option in terms of its value.

How To Choose The Right Underlayment For Your Roof

Now that you have a grasp of the most common types of roof underlayment let’s find out which one’s the right for you.

Roofing Type

The most important factor to consider when choosing a roofing underlay is your roof type. Shingled roofs work well with felt or rubberized asphalt, while metal roofs are best accompanied by a synthetic roof membrane.


If you live in a state where the temperatures are consistent with no radical changes, you shouldn’t have an issue with felt. However, synthetic, and especially rubberized asphalt roofing membrane, excels in areas with fluctuating or extreme temperatures, like Florida or Southern California.

What Is The Best Underlayment For Roofing

Rubberized asphalt is generally considered the best underlayment for roofing. However, with it being so expensive, many homeowners opt for the equally great synthetic one, while folks in more stable climates usually go for the cheaper one, this being felt.

As we mentioned above, the best roofing underlay for you will depend on where you live, what type of roof you have, and what budget you’ve set aside for it.

Choose the Best Underlayment For Your Roof, the Wise Way

Whether replacing your roof or getting some repairs done, taking the underlay into consideration is a must. If you’re in Southern California and are considering changing your roofing underlayment, we’re here for you!

At Roofing Wise, we’ll help you choose the best underlayment for your roof the wise way. Call us now at (833) 315-7663 for a free estimate!

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