Ultimate Guide To Roofing Underlayment

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Ultimate Guide To Roofing Underlayment

Ultimate Guide To Roofing Underlayment

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When thinking of a roof, we know it’s what sits atop of our homes shielding us from the heat and rain. We stay safe and dry indoors all throughout our daily lives because of it.

It’s easy to see a roof as an exterior part of your house, but most wouldn’t know about its roofing system. You also might not be familiar with what a roofing underlayment is.

What exactly keeps a roof strong after years of exposure to all types of weather? Read on below to know why a roofing underlayment is crucial for your roof’s protection.

What Is A Roof Underlayment Used For?

The roofing underlayment is a protective layer on the surface of your roof deck. Oftentimes, it’s a water-resistant material that prevents your roof deck from water intrusion.

Underlayment linings are one of the main layers on your roof that are hardly visible to the eye. Unless you’re someone who’s hands-on with your roofing structure, this layer is unseen.

A roof underlayment also serves as a barrier from exposure to heat, rain, and snow. It protects your roof deck from severe weather conditions or harmful precipitation.

Knowing how an underlayment for roofing keeps your surface sturdy is important. If you want your roof to last you for a long time, it’s best to know what type of roof underlayment works for you.

Types of Roof Underlayment

There are various types of roofing underlayment, all of which cannot take on the same stress. These roofing materials vary in performance to withstand extreme weather conditions.

When it comes to equipping your roof with the ultimate protection, each type has its own capacity. We’ve listed below the three main types of underlayment for homeowners to choose from:

Asphalt-Saturated Felt

Asphalt-saturated felt is a water-resistant type of underlay for roof structure. It was the most popular type of roof underlayment until synthetic products came into the picture.

Also known as tar paper or felt paper, this material is a mixture of asphalt, polyester, and bitumen. It’s also often made of organic substances, which includes a cellulose base.

Its base layer is a flexible substance which is like tar in function. Instead, the basemat is asphalt-saturated, which makes up the water-resistant component.

The asphalt-saturated felt enhances your roof deck’s stiffness. This makes it durable from hailstones, debris, and heavy impacts from solid objects.

Rubberized Asphalt

The rubberized asphalt is a waterproof material. It consists of high concentrations of asphalt and rubber polymers. 

Among other underlay roofing types, this is the only waterproof type with a 100% waterproof seal. Waterproof materials are superior for colder or snowy regions. The rubberized asphalt works against possible water damages on your roof deck. 

These often come with their own self-adhesive, protected by a peel-off membrane. The rubberized asphalt is also a self-sealing underlayment. It’s perfect for sealing around fasteners.

Some rubberized asphalt underlayments include polyester film or fiberglass to prevent moisture build-ups.

Because of the materials used in this type of roofing underlayment, it’s more expensive compared to other under products.

Non-Bitumen Synthetic Underlayment

Modern roofs are likely to use non-bitumen synthetic underlayment. It’s the most preferred roofing underlay material by professionals today.

The non-bitumen synthetic underlayment is still saturated with asphalt for its basement. It incorporates fiberglass, which is a fiber-reinforced type of plastic. This makes it display exceptional tear resistance and elasticity.

Like the asphalt-saturated felt, synthetic underlayment is water-resistant. Since the material doesn’t absorb moisture, it fights off against fungal growth and wrinkles.

Apart from being light-weight and non-skid, most prefer the synthetic underlayment for its UV resistance. It works well to prevent damaging your roof’s surface from excessive heat.

Benefits of Having a Roof Underlayment

Being familiar with a roofing underlayment makes it clear that shingles alone cannot protect your roof. Different elements and weather conditions test your roof over time.

For a better idea of how underlayment materials function for your roof, here are some of its key benefits:

Heat And Moisture Barrier

Shingles are the outermost coverage of the roof deck. They reflect sunlight, wind, and rain from your roof’s surface.  They also overlap each other, leaving minimal spaces around its corners.

The spaces allow water and moisture to pass through during heavy rain or snow. During hot days, heat builds up in your attic space which can weaken your shingles.

Roofing underlayment provides protection against any weather condition that shingles itself cannot withstand.


The shingles on the surface of your roof deck tend to grow brittle over time due to weather exposure. One of the things that weakens the outer surface is moisture build-up.

A water-resistant roofing underlayment allows water droplets to slide off the surface. For water-resistant materials, asphalt-saturated felt and synthetic underlayment are good options.


Waterproofing provides a different function from water-resistance. If your roof consists of valleys, hips, and dormers, it’s likely to leak in those areas during heavy rain.

Asphalt shingles are often used to prevent potential water leakages. A waterproof roofing underlayment is a protective barrier for your roof’s outermost layer.

For a waterproof underlayment that prevents leakages, rubberized asphalt is the best option, laid under drip edge.

Is Synthetic Roofing Underlayment Better Than Felt?

Asphalt-saturated felt is still popular for steep-sloped roofing structures. They’ve existed longer than other types of underlayment materials. Most are also accustomed to its ease of installation on their roof decks.

Non-bitumen synthetic underlayment is a more modern type of material. Often preferred by professionals, it boasts of stronger material composition over the former.

It comes with advanced functions that keep your roof protected at all costs. With this, it’s more expensive than the felt underlayment.

If you’re after more roofing reinforcement, synthetic underlayment has more benefits. For budget shoppers, there’s no harm in going with the traditional felt underlayment.

Final Note

Roofing underlayment is essential if you want to prolong your roof life. Being exposed to different elements all-year-round tests your roof’s durability.

Prevention is better than dealing with the cost of repairs from extensive damage. Your roofing deck can only take so much with shingles alone.

If you prefer a quicker solution for roofing underlayment, asphalt-saturated is a guaranteed material over the years.

For a more modern material, you will appreciate the synthetic underlayment for the benefits it offers.

Lastly, if you have no budget limitations, you could also go for the rubberized asphalt. It’s a durable barrier against one of the most common roofing problems, which is water leakage.

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