Choosing the Best Underlayment for Your Metal Roof: Do You Need Tar Paper?

When it comes to installing a metal roof, you might be wondering, “Do I need tar paper?” It’s a common question, and the answer isn’t always straightforward. The use of tar paper, also known as roofing felt, can depend on a variety of factors, including your location and the specific type of metal roof you’re installing.

Tar paper serves as a barrier between your roof and the elements, offering an extra layer of protection. But is it necessary for a metal roof? Let’s delve deeper into this topic and explore the pros and cons of using tar paper under a metal roof. This will help you make an informed decision for your roofing project.

Key Takeaways

  • Tar paper, or roofing felt, is a secondary barrier installed under the roof, enhancing the roof’s resilience against environmental elements like heavy rainfall, preventing leaks and providing an extra layer of insulation.
  • The use of tar paper under a metal roof is not universally necessary and its effectiveness can vary depending on factors like type of metal roof, geographical location, weather conditions, building design, and local building codes and regulations.
  • Tar paper is generally suitable for roofs with steep slopes and in geographical locations prone to heavy rainfall or snowfall due to its water-resistant properties. It is also cheaper than synthetic underlayments.
  • Tar paper can have adverse chemical reactions with certain types of metals, such as copper and zinc, causing corrosion, and may not be suitable if your local building code or roof warranty requires a specific type of underlayment.
  • While tar paper is reliable as a water barrier, provides short-term protection, is compatible with many roofing materials, and often meets building code and warranty requirements, it can have downsides like decreased durability, moisture absorption, non-breathability, and a more skill-demanding installation process.
  • Other underlayment options like synthetic underlayment and rubberized asphalt offer benefits like improved safety during installation, high tear resistance, self-healing qualities, and better sealing around roof fasteners, but may have a higher upfront cost.

When installing a metal roof, choosing the right underlayment is critical to ensure longevity and durability; tar paper is often used for its water-resistant properties, but there are more advanced alternatives like synthetic underlayments, which Home Depot provides insights on. Synthetic materials offer better performance and can handle temperature extremes better than traditional felt tar paper, a benefit that Roofing Calculator discusses in their comprehensive comparison of underlayment types. For those considering eco-friendly options, recycled synthetic underlayments are available that provide superior moisture protection and environmental benefits, as Green Building Advisor reviews the best practices in selecting sustainable roofing materials.

Understanding Tar Paper for Roofing

When you think about roofing, one of the elements that don’t often come to mind is tar paper or roofing felt. So, what’s it exactly? It’s an underlayment, a layer of material installed between the roof deck and the roofing material. In this case, our focus is on metal roofing. Here, you’ll learn about its purpose and benefits when used under a metal roof.

Primarily, tar paper acts as a secondary barrier, enhancing your roof’s resilience against environmental elements. Depending on your location, this can make a huge difference. If you’re in an area with heavy rainfall, for example, it helps in preventing leaks into your building. It’s like an insurance plan. Would you prefer to face heavy storms with an extra layer of protection, or would you instead take the risk?

Using tar paper under a metal roof also provides an extra layer of insulation. This advantage might not be as palpable as preventing leaks, but it’s still significant. Physical barriers, like tar paper, can limit the exchange of heat, assisting in managing indoor temperature. This could translate to a reduction in energy usage and, subsequently, lower electricity bills. So, if you live in exceptionally hot or cold climates, tar paper insulation might be beneficial. Interestingly, the strategic use of materials to maximize efficiency and protection is much like how Italy and France might strategically employ tactics in a football or baseball match or how a motorcycle must be equipped to handle the varying terrain and weather conditions of a tour through these countries.

In the next section, we will delve into the pros and cons of using tar paper under a metal roof. This way, you will have comprehensive knowledge before making your final call.

Factors to Consider for Metal Roof Installation

Choosing the best underlayment for your metal roof isn’t just about whether to use tar paper or not. There are other variables you need to consider too. Have a look at these important factors:

1. Roof Slope: Your roof’s slope significantly affects your choice of underlayment. Generally, roofs with steep slopes (more than 3:12) do well with tar paper since it provides an added layer against snow and rain. On the contrary, for lower sloped roofs (less than 3:12), you may want to consider self-adhering underlayment or rubberized asphalt.

2. Climate: Your geographical location’s weather patterns play a crucial role in determining the right underlayment. Tar paper is more suitable for areas that experience lots of rainfall or snowfall. This is due to its water-resistant properties which provide added protection against leaks.

3. Material Compatibility: The compatibility of your metal roofing material with tar paper is critical too. Certain types of metals, such as copper and zinc, can have adverse chemical reactions with tar paper resulting in corrosion. Always consult with your roof installer before making a decision.

4. Budget: While tar paper is generally less expensive than synthetic underlayments, costs can add up depending on your roof’s size and complexity.

5. Building Code: Many states have specific regulations about the type of underlayment you can use for metal roofs. Ensure you are aware of your local building code requirements to avoid any potential legal pitfalls.

6. Warranty: Lastly, your chosen roofing material manufacturer’s warranty could require a specific type of underlayment. Failing to stick to these stipulations could void the warranty.

The table below summarizes the major points for easy reference:

Roof SlopeSteep slopes do well with tar paper. Low slopes require self-adhering underlayment.
ClimateAreas with heavy rainfall or snowfall benefit from tar paper’s water resistance.
Material CompatibilityCertain metals might react adversely with tar paper.
BudgetTar paper is generally cheaper but costs will vary.
Building CodeEnsure alignment with local regulations.
WarrantyMay require a specific underlayment to remain valid.

Pros of Using Tar Paper Under Metal Roof

So, why should you use tar paper under your metal roof? Well, there are numerous noteworthy benefits to consider.

For one, it’s a reliable water barrier. Rain, snow, and condensation can accumulate on your roof. Tar paper prevents these water elements from seeping into your home’s structure. This benefit greatly reduces the risk of leaks, moisture damage, and the growth of mold.

Table 1 shows the comparison of the effectiveness of tar paper versus other underlayment types in preventing water infiltration.

Underlayment TypeEffectiveness in Preventing Water Infiltration
Tar PaperVery High
Self-adhered bituminousMedium
Rubberized asphaltMedium

Secondly, the cost factor is also favorable. Compared to other underlayment options like rubberized asphalt or synthetic materials, tar paper is definitely less costly. It fits within most homeowners’ budgets without compromising on quality.

Next, don’t ignore the ability of tar paper to provide short-term protection. In case of delays in the installation of metal roofing, tar paper can withstand exposure to elements to a certain extent.

Lastly, compatibility is another big plus. Tar paper is known to work seamlessly with most roofing materials. Be it metal, asphalt shingles or wood – tar paper serves as a flexible and effective underlayment.

And yes, tar paper can indeed prove beneficial for both low slope and steep roofs. While steeper slopes would particularly benefit due to increased water runoff, lower slopes too gain from the additional layer of protection that tar paper provides.

Remember, adhering to manufacturer warranties and building code regulations is critical. Tar paper meets most of these requisites making it appealing to contractors and homeowners alike.

On to the next section then, where we’ll explore some of the potential drawbacks of using tar paper under metal roofs.

Cons of Using Tar Paper Under Metal Roof

While tar paper can be a good underlayment choice for your metal roof, it’s crucial to consider some potential drawbacks too. Recognizing these cons will help you make an informed decision. After all, knowledge is power.

One downside to using tar paper is its reduced durability. Over time, tar paper can break down under exposure to sun and heat, losing its protective properties. This vulnerability becomes more apparent in particularly hot or harsh climates. It means you may need to replace your underlayment sooner than you’d like.

Next, let’s talk about its integrity during wet weather. Tar paper has a knack for absorbing moisture. If left exposed for long periods during construction delays, it can swell or buckle. This absorption can potentially compromise your roof’s structure—a concern you wouldn’t want to overlook.

Moreover, be aware that tar paper is a non-breathable material. Why’s that an issue, you ask? It can trap condensation, leading to moisture-related issues, such as mold and mildew growth.

Lastly, when weighing your options, consider the installation process. Installing tar paper requires a fair bit of skill. Given its tendency to tear, poor installation can inadvertently lead to water leaks, undermining the very purpose of your underlayment.

Here’s a quick rundown of the cons:

Cons of Tar Paper
Reduced durability
Absorbs moisture
Non-breathable material
Skill-demanding installation

The objective here is not to dissuade you from using tar paper but rather to keep you informed about its potential downsides. Remember, the goal is always to protect your roof and, ultimately, your home.

Making an Informed Decision

Taking into account the potential downsides of using tar paper under your metal roof can seem daunting. The reduced durability due to sun exposure, possible moisture absorption causing structural issues, condensation problems from non-breathability, and the intricate skill-demanding installation process. All these accrue to making one robust, informed decision.

Knowing these facts will allow you to assess your options judiciously before taking the plunge. There are other underlayment options that rival tar paper in terms of durability, water-resistance, and ease of installation.

Some alternative options for underlayment include:

  1. Synthetic Underlayment: This is usually made from polyethylene or polypropylene, these synthetic models offer improved walking safety during installation and high tear resistance.
  2. Rubberized Asphalt: This material has increased self-healing qualities and better sealing around roof fasteners.

These alternatives, however, may have a higher upfront cost compared to tar paper. Yet, the long-term benefits like enhanced durability and reduced maintenance could offset the initial expense.

Aside from material choice, remembering to take the local climate into account can also influence your decision. Areas with high temperatures or excessive rainfall may fare better with a specialized roofing underlayment that caters to these unique conditions.

Taking a moment to discuss your options with a professional roofer can also prove to be beneficial. Every home is different and your home might have specific needs that are best addressed by a professional. They can offer insights derived from years on the job, which can guide you in making the best choice for your specific situation.

Arming yourself with information is vital and the decision ultimately rests in your hands. What’s important is that you are comfortable with your choice and confident in its ability to protect your home. This article’s intention has been to help shed light on the complexities of roofing underlayment.


You’ve got a lot to consider when it comes to picking the right underlayment for your metal roof. Synthetic underlayment and rubberized asphalt are solid choices, offering durability and easy installation. They might cost a bit more upfront, but their long-term benefits may outweigh the initial investment. Remember, your local climate plays a crucial role in this decision. Don’t hesitate to seek professional advice to ensure your choice meets your home’s specific needs. Armed with this knowledge, you’re now ready to make a decision that will confidently protect your home. Selecting the right roofing underlayment may be complex, but it’s a vital step in safeguarding your home’s longevity.

Frequently Asked Questions

What is the importance of choosing the right underlayment for a metal roof?

Choosing the right underlayment for your metal roof is crucial as it impacts the roof’s longevity, durability, and capacity to withstand weather conditions. The right choice can save money on future maintenance or replacement costs.

What are some alternative options for metal roof underlayment?

Some alternative options for metal roof underlayment include synthetic underlayment and rubberized asphalt. Despite their potentially higher initial costs, these options are praised for their durability and easy installation.

How does local climate affect the choice of underlayment?

Local climate can significantly impact the performance of your roof underlayment. For instance, areas with high rainfall levels might require more water-resistant options, while regions with harsh winters might benefit from insulating underlayment.

Why should I consult with a professional roofer?

Consulting with a professional roofer is advised as they can provide a professional assessment of your specific home needs, helping to make the most informed and tailored choice of roof underlayment.

What is the ultimate goal when choosing roofing underlayment?

The ultimate goal when choosing roofing underlayment is to protect your home effectively. The right underlayment selection can improve the lifetime of your roof, offer better protection against weather conditions, and can result in savings in the long run.