Is Roofing Felt Waterproof? How to Tell if Felt Can Stand Up to Rain

If you’re in the market for a new roof, it’s a good idea to know what kind of roofing material you’re using. 

Roofing felt is one of the most common types of roofing material, and there are a lot of reasons why it’s so popular. But does it have any waterproof properties? And if so, how much? 

Let’s take a look at this important topic.

Is roofing felt waterproof?

Roofing felt is a material that is used as a protective layer under roofing shingles. It is made of a layer of fiberglass or polyester mat that is coated with asphalt or another waterproofing agent.

Even though it isn’t completely waterproof, it is resistant to water and helps keep water from getting into the building through the roof shingles.

It is used to add an extra layer of protection against water damage when building or fixing roofs, but it should not be relied on as a sole waterproofing method.

What is roofing felt?

Roofing felt, sometimes incorrectly referred to as “tar paper,” is a type of material that is used as a protective layer under roofing shingles. It is typically made of a layer of fiberglass or polyester mat that is coated with asphalt or another waterproofing agent. Roofing felt is used to add extra protection against water damage when a roof is being built or fixed.

The purpose of roofing felt is to create a barrier between the roofing shingles and the underlying structure of the building. It helps prevent moisture from seeping through the roofing shingles and into the structure, which can cause damage to the building’s framing and other components. Roofing felt is also used to smooth out rough spots on the roof so that the shingles can be laid on a more even surface.

Roofing felt comes in rolls and is typically installed by a professional roofing contractor. It is usually put down before the shingles are put on the roof, and then the shingles are put on top of the felt. In some cases, roofing felt may also be used as a temporary roofing material, installed over the top of an existing roof to provide protection until a more permanent solution can be put in place.

The general consensus is that roofing felt can withstand long-term environmental exposure. You can even leave roofing felt outside for about 6 to 12 months.

What are the benefits of using waterproof roofing felt?

  • Waterproofing quality: Roofing felt is designed to be resistant to water and helps to prevent moisture from seeping through the roofing shingles and into the structure of the building. This can help to protect the interior of the building from water damage and mold growth.
  • Protection against damage caused by rain: Because roofing felt is waterproof, it helps to protect the roof and the building from damage caused by rain. This can help to extend the life of the roof and reduce the need for costly repairs.
  • Ability to withstand harsh weather conditions: Roofing felt is designed to be durable and able to withstand harsh weather conditions, such as high winds and heavy rain. This makes it an ideal choice for roofs in areas that experience extreme weather.
  • Ease of installation: Roofing felt is relatively easy to install, especially when compared to other roofing materials. It comes in rolls and can be applied quickly and efficiently by a professional roofing contractor.
  • Variety of options to choose from: There are a variety of different types of roofing felt available, including those made from fiberglass, wood cellulose, polyester mat, and those coated with asphalt or other waterproofing agents. This allows homeowners to choose the option that best meets their needs and budget.
  • Long-lasting results: When installed properly, roofing felt can last for many years, providing ongoing protection for the roof and building.
  • Budget-friendly cost: Roofing felt is generally less expensive than other roofing materials, making it a budget-friendly option for homeowners. When you account for the number of benefits and savings that roofing felt can potentially save you, it could add up.
  • Decreased risk of leaks and roof damage: By providing an extra layer of protection against water and snow, roofing felt can help to reduce the risk of leaks and roof damage.
  • Improved home safety and security: A well-maintained roof is an important part of any home’s safety and security. By using waterproof roofing felt, homeowners can help to ensure that their roof is in good condition and able to protect their home.
  • Warranty and assurance from manufacturers: Many manufacturers of roofing felt offer warranties on their products, giving homeowners added peace of mind and assurance that they are making a good investment in their home.

Is roofing felt necessary?

Whether or not roofing felt is necessary will depend on the specific circumstances of the roof and the requirements of the building code in your area.

In many cases, it is necessary according to many state regulations.

Depending on where you live, you probably shouldn’t be surprised by it being required by local building codes or suggested by a roofing contractor.

For more than 25 years, organizations such as the National Roofing Contractors Association (NRCA) and the Canadian Asphalt Shingle Manufacturer’s Association (CASMA) have included roofing felt in their roofing and waterproofing recommendations.

How can I tell if roofing felt is waterproof?

  • Check the manufacturer’s specifications: Roofing felt specifications from the manufacturer often include information about how well it keeps water out. Make sure to read the details carefully to find out if the felt is meant to be waterproof or just resistant to water.
  • Research the felt’s waterproofing capabilities: In addition to checking the manufacturer’s specifications, you can also research the felt’s waterproofing capabilities by looking for information online or by contacting the manufacturer directly. This can help you to get a better understanding of the felt’s performance in wet conditions.
  • Research the felt’s ability to withstand extreme weather conditions: In addition to its waterproofing capabilities, consider the felt’s ability to withstand extreme weather conditions. This is particularly vital if you live in an area that experiences extreme weather, such as high winds or heavy rain.
  • Consult reviews of the felt’s waterproofing capabilities: Reading reviews from other users of the roofing felt can give you a sense of how well the felt holds up in wet conditions. Look for reviews that specifically mention the felt’s waterproofing performance.
  • Compare felt brands and versions to see which ones are the most waterproof: There are many different brands and versions of roofing felt available, and they may vary in their waterproofing capabilities. Comparing different options can help you to identify the most waterproof options. Some of the best-recommended roofing felt manufacturers are Gaf FeltBuster, Grip-Rite, and GCP.
  • Look for certifications or seals of approval for waterproofing: Some roofing felts may be certified or have seals of approval from organizations that test and certify waterproofing products. These certifications can provide additional assurance that the felt is waterproof.
  • Consider the felt’s thickness: In general, a thicker roofing felt is more likely to be waterproof than a thinner felt. This is because a thicker layer of material provides a more effective barrier against water.
  • Ask for references from previous customers: If you are considering using a particular brand or version of roofing felt, you may be able to ask a contractor for references from previous customers who have used the felt. This can help you to get a sense of how well the felt performs in real-world conditions.
  • Read reviews from users to determine how well the felt holds up in rainstorms: In addition to consulting references from previous customers, you can also read reviews from users of the roofing felt to get a sense of how well it holds up in rainstorms and other wet conditions.
  • Ask experts for advice: If you are unsure whether a particular roofing felt is waterproof, you can also ask experts, such as roofing contractors or professionals in the building materials industry, for their advice. They may be able to provide additional information and insights to help you make an informed decision.
  • Investigate the materials in the felt: Finally, you can also investigate the materials that are used to make the roofing felt. Some materials, such as fiberglass or polyester mat, are more water-resistant than others. By understanding the materials that are used to make the felt, you can get a better sense of its waterproofing capabilities.

What is the difference between roof felt and roofing shingles?

Roof felt and roofing shingles are two different types of materials that are used in roof construction and repair. 

Roof felt is put down under the shingles. It is typically made of a layer of fiberglass or polyester mat that is coated with asphalt or another waterproofing agent. 

On the other hand, roofing shingles are the part of the roof that you can see and that protects it from the weather. They are made of a variety of materials, such as asphalt, wood, or slate, and are designed to be durable and long-lasting. 

The primary difference between roof felt and roofing shingles is the purpose that they serve in the roofing system. Roof felt is used as a protective layer under the shingles, while roofing shingles are the visible, outer layer of the roof that protects your house directly from the environment.

What is the difference between felt and other roofing materials?

So, the difference between felt and other roofing materials is that felt is a type of material that is used as a protective layer under the visible, outer layer of the roof.

The purpose of the felt is to provide an extra layer of protection against water damage, helping to prevent moisture from seeping through the roof and into the structure of the building. 

Other roofing materials, like asphalt shingles, wood shingles, or slate tiles, make up the roof’s visible outer layer that is exposed to the weather. 

These materials are made to be strong and last a long time. They keep the roof and building safe from the weather.

What kind of damage can wet felt cause?

Wet felt can cause a number of problems if it is not properly maintained and kept dry. Some of the potential damage that wet felt can cause include the following:

  • Rot: Wet felt can become saturated with water and may begin to rot, especially if it is made of organic material such as asphalt or wood. Rotting felt can weaken the structural integrity of the roof and may need to be replaced.
  • Mold growth: Wet felt is also prone to mold growth, which can cause further damage to the felt and the underlying structure of the roof. Mold growth can also be a health hazard, as it can release spores into the air that can cause respiratory issues.
  • Degradation of the felt: Wet felt can also degrade over time, especially if it is exposed to water for long periods of time. This can weaken the felt and make it more prone to tearing or puncturing, which can compromise the waterproofing capabilities of the roof.
  • Leaks: Wet felt is more likely to develop leaks, as the water can seep through the felt and into the structure of the building. Leaks can cause damage to the building’s framing, insulation, and other components, and can also lead to the growth of mold and other types of damage.

Properly maintain and protect the roofing felt to help prevent this type of damage. This may include installing a protective layer over the felt, such as a layer of roofing shingles, and regularly inspecting and repairing any damage to the felt.

What is another roofing underlayment you use for waterproofing?

There are several types of roofing underlayment that can be used for waterproofing. Some of the most common options include:

  • Synthetic underlayment: Synthetic underlayment, also known as synthetic felt, is made of synthetic material, such as polypropylene or polyethylene, and is coated with a waterproofing agent. Synthetic underlayment is lightweight, durable, and easy to install, and it provides good protection against water.
  • Rubberized asphalt underlayment: Rubberized asphalt underlayment is made of asphalt that is mixed with rubber to make it more flexible and water-resistant. It is a good option for roofs that experience a lot of movement, such as those with wide temperature fluctuations.
  • Peel-and-stick underlayment: Peel-and-stick underlayment is a type of underlayment that is applied directly to the roof deck and is held in place with self-adhesive backing. It is a good option for roofs that are prone to leaks, as it provides an extra layer of protection against water.
  • Ice and water shield: Ice and water shield is a heavy-duty underlayment that is designed to provide protection against water and ice dams. It is typically used in areas where freezing temperatures and snow are common.

What type of material is roofing felt made from?

Roofing felt is typically made of a layer of fiberglass or polyester mat that is coated with asphalt or another waterproofing agent.

The fiberglass or polyester mat provides the basic structure of the felt, while the asphalt or other coating helps to make it waterproof. 

Some roofing felts may also be made from other materials, such as organic materials such as wood or paper, or from synthetic materials such as polypropylene or polyethylene. 

The specific material used to make roofing felt will depend on the manufacturer and the intended use of the felt. In general, roofing felt is designed to be durable and resistant to water, and it is used in roof construction and repair to provide an extra layer of protection against water damage.

What is tar paper, and how does it relate to roofing felt?

Tar paper is a type of material that is used in roof construction and repair as a protective layer under roofing shingles.

People often use the terms “tar paper” and “roofing felt” to talk about the same kind of material. Both tar paper and roofing felt are made of a layer of fiberglass or polyester mat that is coated with asphalt or another waterproofing agent.

However, there’s a major difference between them. Tar paper is made of a tear-resistant paper or fiberglass and is soaked in tar. Roofing felt is made of recycled paper and aspalth is added to it.

Like roofing felt, tar paper is used to add an extra layer of protection against water damage. It keeps water from getting through the roof shingles and into the building’s structure. It is usually put down before the shingles are put on the roof, and then the shingles are put on top of the tar paper.

Tar paper isn’t meant to be a waterproofing solution on its own. Instead, it should be used with other roofing materials, like shingles or tiles, to make a complete system for keeping the roof dry.

What are the dangers of using felt underlayment?

One potential danger is the risk of fire. 

Some felt underlayments may be made of a layer of polyester mat that is coated with asphalt or another flammable material. If the underlayment is exposed to high temperatures or open flames, it could ignite and cause a fire. 

Also, if felt underlayment isn’t installed or maintained properly, it can soak up water, which can cause rot, mold growth, and other problems with the roof and building. 

Wet felt is also more likely to leak, which can damage the building’s structure, insulation, and other parts. 

To avoid these kinds of problems, keep the felt underlayment in good shape and keep it safe.

How often should felt underlayment be replaced?

The age of the underlayment, the condition of the roof, and the weather in the area will all affect how often it needs to be replaced. In general, felt underlayment is made to last for a long time if it is installed and cared for properly. 

But check the underlayment often and fix any damage when necessary. If the underlayment is showing signs of wear or deterioration, such as tears, punctures, or rot, it may need to be replaced.

Talking to a professional roofing contractor is a good idea. They can look at the underlayment and tell you if it needs to be fixed or replaced. 

In general, you can expect felt underlayment to last for at least 10–20 years when it is properly installed and maintained. However, if your felt underlayment is exposed and not covered by shingles, expect it to last anywhere from 6 to 12 months.

Depending on the roof’s situation, the contractor can also tell you how often the underlayment should be checked and replaced.

What should you do when roofing felt gets wet and damaged?

If the roofing felt gets wet, take steps to dry it out as soon as possible to prevent further damage. Here are some steps you can take when roofing felt gets wet:

  1. Remove the source of the water: The first step in addressing wet roofing felt is to identify and remove the source of the water. This could mean fixing any leaks or fixing any damage to the shingles or other roofing materials.
  2. Dry out the felt: Once the source of the water has been addressed, dry out the wet roofing felt. This can be done by using a hair dryer or a heat gun to carefully apply heat to the felt, or by using a fan to circulate air over the felt.
  3. Repair any damage: If the roofing felt is damaged, such as if it is torn or punctured, it will need to be repaired or replaced. This should be done as soon as possible to prevent further damage to the roof and house.
  4. Protect the felt: To help prevent future water damage, protect the roofing felt from future exposure to water. This may involve installing a protective layer over the felt, such as a layer of roofing shingles, or sealing any gaps or seams in the felt to prevent water from seeping through.
  5. Inspect the felt regularly: To help ensure the continued performance of the roofing felt, regularly inspect the felt and repair any damage as needed. This can help to extend the lifespan of the felt and protect the roof from water damage.

How long can you leave roofing felt exposed?

Sometimes, roofing felt is used as a temporary layer of protection under the shingles. If it were left out in the open, it would probably only last 6 to 12 months. It is not meant to be left out in the weather for long periods of time. 

In general, it is best to put the shingles on the roof as soon as possible after putting down the felt to protect it from the weather. If the felt must be left exposed for an extended period of time, take steps to protect it from water damage. 

This could mean putting a temporary cover over the felt, like a tarp or a sheet of plastic, or sealing any holes or seams in the felt to keep water from getting in. 

Ultimately, the length of time that roofing felt can be left exposed will depend on the specific circumstances of the roof and the weather conditions in the area. 

It is always a good idea to consult with a professional roofing contractor who can provide guidance on the best course of action in your specific situation.

How long does it take for roofing felt to dry?

The amount of time it takes for roofing felt to dry will depend on a number of factors, including the humidity and temperature of the environment, the thickness of the felt, and the amount of water that has been absorbed by the felt. 

In general, it can take anywhere from a few hours to a few days for roofing felt to dry, depending on the specific circumstances. If the felt is only slightly damp, it may dry out relatively quickly, while if the felt is heavily saturated with water, it may take longer to dry. 

To speed up the drying process, you can use a hair dryer or a heat gun to carefully apply heat to the felt or use a fan to circulate air over the felt. 

Dry out the felt to prevent further damage, such as rot or mold growth. If the felt is damaged or cannot be adequately dried out, it may need to be replaced.

Does felt protect my roof from fire damage?

It is meant to add another layer of protection against water damage, but it is not always meant to protect against fire damage. 

Luckily, roofing felt is not very flammable, and if it is put down under the roof shingles, it may help protect against some fire damage. 

But it is not a fireproof material on its own, so it shouldn’t be used as the only way to protect a roof from fire damage. 

To protect a roof from fire damage, use fire-resistant roofing materials, like Class A shingles, and to take other fire prevention steps, like keeping the area around the building clear and installing smoke detectors and fire sprinklers.

How much roofing felt do I need?

Home size (sq. ft.)Approximate roof size (sq. ft.)Approximate amount of roofing felt (sq. ft.)
100014001540
150021002310
200028003080
250035003850
300042004620
350049005390
400056006160
450063006930
500070007700
This helps you estimate how much roofing felt you might need based on the square footage of your home and the estimated area of your roof

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Logan
Author: Logan

I help people connect with businesses