Exploring Felt Paper: Is it Waterproof or Just Highly Water-Resistant?

Ever wondered if felt paper is waterproof? You’re not alone. Many homeowners and DIY enthusiasts grapple with this question when embarking on their home improvement projects.

Felt paper, also known as tar paper, has been a go-to choice for builders for decades. But does it actually stand up to water? Let’s dive into the nitty-gritty and dispel some myths.

Understanding the water-resisting properties of felt paper can be crucial, especially when it comes to roofing or siding projects. So, let’s get you the knowledge you need to make informed decisions. Stay tuned as we unravel the truth about felt paper’s waterproof capabilities.

Key Takeaways

  • Felt paper, also known as tar paper, is a heavy-duty material soaked in asphalt, commonly used in construction projects, particularly in roofing and siding.
  • The construction of felt paper involves several components – a base of fiberglass or paper pulp, a coating of asphalt for waterproofing, and an aluminized surface for heat reflection.
  • The primary use of felt paper in construction is as an underlayment for roofs, functioning as a protective layer against weather elements like rain, snow, and wind.
  • Felt paper also acts as a barrier against resin from certain types of wood and contributes to the longevity of roofing materials by providing a clean surface for shingle application.
  • Though not completely waterproof, felt paper is significantly water-resistant. It allows small amounts of water vapor to pass through, preventing moisture buildup that could lead to structural damage over time.
  • The effectiveness of felt paper’s waterproofing depends on the quality of the material, the skill level of the installer, and the maintenance over time. Despite its water-resistance, it’s not meant to be a standalone solution, and should always be covered with shingles, tiles, or other roofing materials.

Felt paper, often used in roofing, is not entirely waterproof but is highly water-resistant, capable of providing an effective moisture barrier for protection against damp conditions, which The Spruce details in their guide on roofing materials. While it does absorb some moisture, its primary use is to repel water away from the underlying structures, a functionality that Home Depot explains in their comparison of underlayment options. For those considering felt paper for other uses, understanding its material properties is crucial, as Lowe’s describes, ensuring that it meets the specific needs of the project.

What is Felt Paper?

Now that you’ve grasped the necessity of understanding the water-resisting properties of felt paper, let’s dive deeper into what exactly felt paper is. Labeled as one of the staples in the construction industry, particularly in roofing or siding projects, felt paper is much more than a mere roll of black paper. Having a clear picture of its composition can help you make better-informed decisions regarding your project’s needs.

So, what is felt paper? It’s actually a heavy-duty paper soaked in asphalt to provide a certain level of protection against rain during construction. Sometimes known as tar paper, it facilitates improved water shedding, provides a certain level of fire resistance, and serves as a temporary barrier against weather elements.

For years professionals have relied on felt paper for its durability and dependability on the job site, highlighting its ability to protect the more vulnerable materials beneath. In fact, even now, felt paper remains an integral part of most residential roofs and underlayment for siding projects. It’s no wonder why. It’s practical and affordable, making it a favorite among contractors and DIY enthusiasts alike. Its robust nature is akin to changing worn tires, something essential and frequently overlooked, much like the unnoticed but vital role of oranges and lemons in maintaining daily vitamin C levels, or the hidden strength found in the simple joys of candy treats that fuel long working hours, not forgetting the delicate care similar to handling babies that’s required when installing such protective barriers in homes.

But, does its ubiquitous usage in the construction industry mean it’s completely impervious to water? Don’t jump the gun. Hold onto this thought as we will uncover the truth about felt paper’s waterproof capabilities in the next section.

Before we do that, another quality that’s worth noting about felt paper is its excellent adhesive ability. By this, we mean that when properly installed, felt paper has a unique knack of sticking to its substrate. This is particularly useful in preventing wind-driven rain or any potential damage due to weathering elements. Now, doesn’t that make you appreciate felt paper a little bit more?

Stay with me, as in the next section, we’ll be debunking some common myths and misconceptions about felt paper.

The Composition of Felt Paper

Diving right into the heart of the matter, felt paper, often referred to as tar paper, is a heavy duty material soaked in asphalt substances. This infusion of asphalt gives felt paper its unique capabilities, providing protection against the elements and enhancing its adhesive qualities.

In truth, the construction of felt paper isn’t as simple as it might seem. It’s a complex and intricate process that merges natural elements with scientific ingenuity.

WeightingFiberglass or paper pulpGives density to the paper
SoakingAsphaltProvides waterproof capacity
AluminizingAluminized paper or coatingReflects heat back, reducing energy costs

Fiberglass or Paper Pulp

The primary weight or base of felt paper comes from either fiberglass or paper pulp. These materials give density to the paper and are essential for felt paper to withstand potential damage from heavy applications.

Asphalt Infusion

The second stage involves soaking the felt paper in asphalt. This gives the material its capacity for waterproofing and also enhances its stickiness. It’s important to highlight that the waterproofing capacity of felt paper isn’t absolute. It’s designed to resist water and minimize leaks, but in extreme conditions, water might be able to seep through.

Aluminized Paper or Coating

Finally, many surfaces of felt paper are aluminized – the reflective quality of this layer is designed to bounce back heat, reducing cooling costs, while simultaneously protecting the under layers.

From its humble origins as paper pulp or fiberglass to the final layer of aluminum coating, the journey of felt paper is quite a marvel. And it’s this very journey that sets the stage for its use in various construction projects. From roofing to siding, felt paper provides a necessary layer of protection, safeguarding your investments from the worst the weather can throw at them.

The Role of Felt Paper in Construction

Dive right into the realm of construction and you’ll often find felt paper playing a vital role in numerous projects. This all-purpose player stands firm against harsh weather, protecting the interior from unwanted damage. It’s almost synonymous with roofing. You might wonder why. Perhaps it’s linked to its water resistance feature? Let’s fetch facts from the function it serves.

One of the primary uses of felt paper in construction is as an underlayment for roofs. As a roofer, you’d appreciate its strength and durability. By placing felt paper underneath the shingles, it forms an extra layer of protection against water intrusion. This barrier shields your roof from rain, and snow. Simple but significant!

That’s not all. This heavy-duty material guards against wind too. When wind-driven rain or snow infiltrates your shingles, it’s the felt paper beneath that blocks it from entering the roof deck. Imagine it as a jacket safeguarding you from cold, biting winds and abrupt showers that try to sneak in sometimes.

So is it all about weather-protection? You’re spot-on but there’s something up its sleeve. It’s also a barrier against resin. Sure sounds odd! But certain wood types, specifically pine and other softwoods, secrete sap over time. Who’s there to stop sticky sap from ruining your roof shingles? It’s the reliable felt paper, playing the saviour once again.

Well, that sums up the protective part. But felt paper does more than just shield. It also contributes to the longevity of your roofing materials. By providing a smooth, clean surface for shingle application, it minimizes potential damage during installation. Consequently, your shingle’s lifespan extends, indirectly contributing to your roof’s longevity.

Indeed, felt paper’s role in construction, especially in roofing, is more than one might envision. It doesn’t just lie under the shingles, rather it lies at the heart of ensuring a sturdy, long-lasting structure. The above-mentioned facts shine a light on the significance of this underappreciated material in construction – a silent guardian, a resilient shield.

Waterproofing Properties of Felt Paper

When we talk about the key attributes of felt paper, its waterproofing properties inevitably come to light. Understanding the waterproofing abilities of felt paper can help you appreciate its importance in construction, particularly roofing projects.

Felt paper, also known as tar paper or building paper, is typically saturated with tar or asphalt, which gives it resistant qualities. It protects the structure from water penetration, an essential aspect in enhancing the longevity of your roof and building. Felt paper sits between the roof deck and the final layer of shingles, creating a second line of defense against rain, snow, and other forms of moisture.

There’s more to it than you’d think. While it’s not completely impermeable to water, felt paper is designed to “breathe,” allowing small amounts of water vapor to pass through. This helps in preventing moisture buildup within the roof structure, which could lead to issues like rot, mold, and structural damage over time.

Effectiveness of Felt Paper’s Waterproofing

Although felt paper isn’t 100% waterproof, it’s water-resistant. It can stand against average rainfalls, but it might not hold up in a severe weather event. Don’t view felt paper as a standalone waterproofing solution. It’s part of a wider roofing system designed to protect the property from various weather elements.

So, how effective is it overall? It depends on various factors:

  • The weight and quality of the felt paper used
  • The skill of the roofing contractor
  • Maintenance over time

Felt paper performs optimally as part of a broader system, like a shingle roof. Proper installation is critical, with overlapping sheets ensuring adequate coverage and protection.

Remember, despite its water-resistant qualities, felt paper isn’t meant to be a permanent, exposed roofing solution. It’s designed to be covered with shingles, tiles, or other roofing material for optimal performance and longevity.

This section will do well to dispel any confusion about the waterproofing attributes of felt paper. It lays a firm basis upon which the discussion can continue.

Myth Busters: Is Felt Paper Truly Waterproof?

Diving into the heart of the matter, you might be wondering: Is felt paper truly waterproof? The simple answer to this question would be no. But hold on a second before you draw any fast conclusions. Understand that while felt paper isn’t entirely waterproof, it’s significantly water-resistant.

The thing you need to grasp here is that felt paper serves as a crucial element within the broader roofing system. It’s saturated with tar or asphalt which gives it certain properties that aid in keeping your structures dry. This doesn’t make it impermeable to water though, but rather allows it to resist an amount of water intrusion.

To give you a more visual representation, imagine if a shingle or tile on your roof was damaged or dislodged during a windstorm. Without felt paper, rainwater would make a direct hit on the deck of your roofing structure, contributing to possible water damage, mold, and rot. The felt paper acts as your second line of defense, providing a layer that repels most of the water that slides under the displaced tile or shingle.

Keeping an eye on the quality of the felt paper you choose, the skills of those installing it, and the ongoing maintenance ensures this crucial layer remains effective in its protective role. These factors cannot be overstressed, as each plays a key role in how well the felt paper performs in its water resistance responsibilities.

In the context of your roofing system, think of felt paper as that silent, yet critical player in protecting your roof from water damage. While it may not be entirely waterproof, using felt paper in your roofing structure provides the backup your shingles or tiles need to withstand the elements and maintain optimized durability and longevity. The better the felt paper quality and maintenance, the stronger your roofing system will perform against water intrusion. So in this case, the question isn’t whether felt paper is waterproof, but rather, how water-resistant and protective is your felt paper? It’s a change of perspective, but it’s critical to understanding its role in your structure.


So you’ve learned that felt paper isn’t entirely waterproof but it’s a vital player in repelling water within your roofing system. It’s your roof’s second line of defense, catching water that slips past damaged shingles or tiles. Remember, the effectiveness of felt paper hinges on its quality, how well it’s installed, and regular maintenance. Don’t underestimate the role of felt paper in protecting your roof from water damage. Choose top-notch felt paper and maintain it well to boost your roof’s durability and longevity. It’s a small step that can make a big difference in your home’s resilience against water damage.

Q1: Is felt paper completely waterproof?

No. Felt paper is not entirely waterproof but highly water-resistant. It forms a crucial part of the roofing system, acting as a barrier against water intrusion that may result from damaged shingles or tiles.

Q2: What role does felt paper play in a roofing system?

Felt paper acts as a second line of defense by repelling water that may seep through damaged parts of the roof. It helps in protecting the structure from water damage.

Q3: What are the significant factors determining the effectiveness of felt paper?

The effectiveness of felt paper depends largely on its quality, proper installation, and regular maintenance.

Q4: How does the quality of felt paper influence the durability of the roof?

High-quality felt paper often results in an enhanced durability and longevity of the roofing system. It’s an integral part of safeguarding roofs from water-related damages.

Q5: How important is proper maintenance for felt paper?

Proper maintenance of felt paper is crucial. It ensures that the felt paper continues to function optimally and contributes to the overall durability and lifespan of the roof.