When planning a metal roof for your home, you might wonder what goes underneath it. The material you choose to place under metal roofing can significantly impact its performance. You have a few main options, such as synthetic underlayment and asphalt-saturated felt. Each option offers different benefits and disadvantages.
In this article, we’ll explore the various materials that can be used under metal roofing, assisting you in making an informed decision for your needs. Let’s get started!
What do you put under metal roofing?
Under metal roofing, a protective layer is important for effectiveness and longevity. Homeowners often choose between two main types of underlayment: synthetic underlayment and felt paper. Synthetic options are durable, offering better resistance to high temperatures and moisture. Felt underlayment, while widely used, tends to degrade quickly under harsh conditions.
A good underlayment not only functions as a vapor barrier but also acts as a noise barrier during rain, making the living space more comfortable. When selecting underlayment, homeowners should consider local building codes, the climate, and even the type of metal roofing installed. Some roofing contractors recommend including a slip sheet or a water shield, especially in areas prone to high winds. This adds a layer of protection, improving the overall performance of the roofing system. Furring strips might also be needed to ensure a strong bond between the underlayment and the roof deck.
Importance of Using Proper Underlayment
Using the right underlayment contributes to the longevity and performance of metal roofs by providing a protective layer between the roofing material and the roof deck. There are various types available, including synthetic options and felt paper. Synthetic underlayment tends to be more durable and withstands high temperatures better than felt, which may deteriorate quickly.
The appropriate underlayment also aids in insulation, enhancing energy efficiency by reducing air leakage and maintainingthermal performance, which can lower energy expenses for homeowners. Conversely, insufficient underlayment, like low-quality felt paper or missing a slip sheet, can result in moisture issues and leaks, potentially causing significant damage. Moreover, using inappropriate materials and neglecting local building codes can undermine the integrity and sustainability of the roofing project.
Consulting with a roofing contractor before making a decision is advisable to ensure that all roofing layers work together effectively.
Types of Underlayment for Metal Roofs
Synthetic Underlayment
Synthetic underlayment provides numerous advantages compared to traditional felt paper. Its remarkable durability reduces the chances of tearing or degrading quickly during roofing installation. Made from materials like polyethylene and enhanced with a rubberized-asphalt or butyl-based adhesive, it forms a strong bond and serves as a reliable moisture barrier.
For metal roofs, synthetic underlayment improves thermal performance, aiding in insulation and functioning as a noise barrier during heavy rain. Homeowners value that these options can endure high temperatures without deteriorating.
When choosing synthetic underlayment, it’s important to consider local building codes, the type of roofing material, and the area’s specific weather conditions. Knowing the permeability rating and ensuring proper installation with elements like furring strips and slip sheets optimizes effectiveness. These factors significantly influence the performance of the roofing system, helping it withstand high winds and other harsh conditions. Consulting with an experienced roofing contractor can help homeowners identify the best underlayment choices for their needs.
Felt Paper Underlayment
Homeowners looking to install metal roofs often choose felt paper underlayment due to its cost-effectiveness and availability. This asphalt-saturated felt provides a waterproof protective layer that can prevent water leakage while acting as a decent noise barrier during storms. However, felt underlayment may degrade quickly under high temperatures compared to synthetic underlayment, which typically lasts longer and offers better moisture resistance.
For optimal performance, it is important to lay down the felt flat on the roof deck, avoiding wrinkles that could compromise its function. A slip sheet can also be considered to protect the felt from damage when installing metal panels. Ensuring proper ventilation can help reduce air leakage and improve thermal performance.
Following local building codes and consulting with a local roofing contractor can help homeowners choose the best underlayment options tailored to their specific needs, including the necessary water shield or adhesive backing for added durability.
Tar Paper Underlayment
Tar paper underlayment, also known as felt underlayment, provides numerous advantages when placed beneath metal roofs. It acts as a barrier that helps keep water from penetrating the roofing material, thereby lowering the chance of leaks. This underlayment is particularly appreciated for its water-resistant qualities, which assist in shielding the roof deck from damage due to strong winds or rain.
Nevertheless, in comparison to synthetic underlayment options, felt underlayment has a shorter lifespan and is less durable, as it can wear out quickly when subjected to high temperatures and moisture.
For proper installation of tar paper underlayment, homeowners should adhere to specific recommendations. Ensuring that the roof deck is clean and dry is important before laying down the underlayment. Overlapping the felt paper precisely helps create a secure bond, preventing water intrusion. Installing furring strips can offer extra ventilation and support, and using a slip sheet alongside the felt can help avoid sticking issues with the metal roofing material. Paying close attention to local building codes will ensure a successful roofing installation.
Choosing the Right Roof Underlayment
Homeowners should think about several factors when selecting underlayment for a metal roofing project. They need to consider the local building codes, as these often dictate which types of underlayment are acceptable. Options like felt underlayment or synthetic underlayment serve different purposes; felt paper may offer better affordability, while synthetic underlayment provides greater durability and insulation.
Climate is also significant, since areas prone to high winds, heavy rain, or high temperatures require stronger protective layers.
Additionally, materials like self-adhering membranes, which use a rubberized-asphalt or butyl-based adhesive, can create a strong bond and act as a vapor barrier. This helps to prevent air leakage and maintain thermal performance. If underlayment degrades quickly, it can affect the longevity of the roofing material, so homeowners need to assess permeability ratings and how different types handle moisture and temperature fluctuations. Lastly, using furring strips or slip sheets can improve installation quality by enhancing the noise barrier properties and stability of the entire roofing system. Consulting with a local roofing contractor can help ensure that the right choices are made.
Installation Process for Metal Roofing
During the installation process for metal roofing, it’s important to prepare the roof deck correctly. The contractor starts by laying down a suitable roofing underlayment, which could be synthetic underlayment or asphalt-saturated felt paper. Synthetic underlayment is known for its durability and resistance to tearing in high temperatures, while felt underlayment offers good adhesive properties but may degrade quickly if exposed to the elements.
Depending on the chosen type, the installation may also involve adding a slip sheet or a self-adhering membrane for extra protection, particularly in windy areas. Homeowners should ensure their roofing contractor follows local building codes and provides a strong bond between the underlayment and the metal roofing material. Applying furring strips can improve insulation and serve as a noise barrier during heavy rains.
Safety measures, such as wearing harnesses and using ladders safely, are important to prevent accidents during the roofing installation.
Additionally, using a water shield can help protect against leaks. Proper ventilation in the structure will mitigate air leakage, further enhancing the roof’s thermal performance.
What do you put under metal roofing? Key Considerations
When choosing underlayment for metal roofing, homeowners should think about durability, thermal performance, and local building codes. Different types of underlayment, such as synthetic underlayment and felt paper, have distinct qualities.
For example, synthetic underlayment typically offers a longer lifespan and better heat resistance compared to felt underlayment, which can degrade quickly in harsh conditions. Climate conditions are also important; regions with frequent high winds or heavy rain may require a self-adhering membrane with strong adhesive properties to ensure effective water protection. Roof pitch matters too, as a steeper slope often requires synthetic felt paper due to its lower permeability rating, which assists in controlling water flow. Consulting a local roofing contractor can offer valuable insights on which underlayment options suit metal roofs, ensuring a solid bond with the roof deck while maintaining insulation and acting as a noise barrier.
For low-slope roofs, incorporating furring strips and slip sheets can enhance performance and safeguard against moisture.
Advantages of Using Synthetic Underlayment
Synthetic underlayment stands out because it offers better durability and weather resistance compared to traditional felt paper options. It lasts longer, often matching the lifespan of metal roofs, which can be 50 years or more. This is especially helpful in high temperatures or during strong winds, where felt underlayment tends to degrade quickly.
The lightweight nature of synthetic underlayment makes it easier for homeowners and roofing contractors to handle during installation, improving project efficiency. Its design allows for faster installation without sacrificing strength.
Additionally, synthetic underlayment significantly enhances energy efficiency. It includes a strong bond, which helps manage moisture and can serve as an effective vapor barrier, minimizing the risk of air leakage and improving thermal performance. This helps create a noise barrier as well, making the roofing system more comfortable. Options like rubberized-asphalt or self-adhering membranes, reinforced with a polyethylene carrier sheet, provide excellent adhesion and protection. These factors are why many local roofing projects recommend synthetic underlayment for metal roofing systems.
Disadvantages of Tar Paper Underlayment
Tar paper underlayment, also known as felt underlayment, faces challenges with moisture retention and breathability due to its higher permeability rating compared to synthetic alternatives. This can result in trapped moisture, causing issues like air leakage and lowering the thermal performance of the roofing system.
The lifespan of tar paper is generally shorter than synthetic options, often lasting around 15 to 20 years, which may lead homeowners to face more frequent replacements and increased overall costs. Installation of felt paper can be tricky; it tends to buckle and wrinkle, complicating the process of laying it flat on the roof deck. In contrast, synthetic underlayment products, such as self-adhering membranes and synthetic felt paper, provide better durability and ease of handling with their adhesive backing. They also contribute to a strong bond and act as a vapor barrier.
Homeowners should consider these factors and discuss underlayment options with a roofing contractor during their consultation to select the best material for their roofing projects.
Factors Affecting Underlayment Choice
Climate Conditions
Choosing the appropriate underlayment for metal roofing is influenced by local climate conditions. Homeowners should assess whether their area deals with high temperatures, heavy rain, or strong winds since these elements can significantly impact the selection between synthetic underlayment and felt paper.
For example, synthetic underlayment, crafted from polyethylene and other polymers, effectively endures high temperatures without deteriorating quickly, while felt underlayment may not perform as well in hot environments.
Additionally, regions prone to rain might require a self-adhering membrane that provides robust adhesive properties and serves as a vapor barrier, blocking moisture from entering the roof deck. Severe weather can reduce the lifespan of underlayment, particularly asphalt-saturated felt, which might lose effectiveness over time. Consulting with a roofing contractor can help evaluate local building codes and identify the best underlayment choices that ensure durability and minimize noise during bad weather. Correct installation, along with components like furring strips or a slip sheet, can further improve performance, helping the roofing system endure tough conditions and retain thermal efficiency.
Roof Pitch
The roof pitch significantly affects the choice of underlayment for metal roofs. For steep pitches, synthetic underlayment is often preferred due to its durability and strength, which helps prevent water leakage and damage. Homeowners may also consider felt paper for its adhesive properties, though it often deteriorates quickly under high temperatures.
Low pitches may need a self-adhering membrane or a rubberized-asphalt water shield to ensure a strong bond and effective vapor barrier against moisture. These types of underlayment address the unique challenges of lower slopes. When handling steep or low pitches, roofing contractors should adjust their installation techniques. A steep roof can allow for faster drainage, while a low pitch might require furring strips or a slip sheet to prevent water buildup.
The appropriate underlayment can improve thermal performance, reduce noise, and enhance the overall durability of the roofing system, in line with local building codes and homeowner needs. Consulting a local roofing expert ensures that the best underlayment options are chosen for any roofing project.
Budget Constraints
Budget constraints can greatly impact the selection of underlayment for metal roofing projects. Homeowners might opt for felt underlayment because it is less expensive, but they may find it lacks the durability of synthetic underlayment. This could result in more frequent repairs or replacements, particularly in high winds or when faced with water penetration.
Choosing a cheaper option may lead to compromises, such as reduced insulation or less effective noise reduction, affecting overall comfort. Investing in higher-quality underlayment, like self-adhering membranes made of rubberized asphalt or polyethylene carrier sheets, can offer a stronger bond and long-lasting protection, even if it stretches the budget. Budget limitations can also affect how well the roofing system endures harsh weather, impacting thermal performance and lifespan. Not adhering to local building codes might make matters worse, as inferior underlayment may degrade rapidly and leave the roof exposed.
Homeowners are encouraged to consult a local roofing contractor to explore underlayment choices that balance cost and quality for their metal roofs.
Maintenance Tips for Metal Roofs and Underlayment
Homeowners should regularly inspect their metal roofs and underlayment for loose panels and signs of wear. During these routine inspections, they should look for damage caused by high winds or high temperatures, as well as check the gaskets and seals for leaks. Cleaning can be done with gentle soap and water to remove debris, which helps prevent rust and degradation of the protective layer.
For metal roof underlayment, checking for proper insulation and ensuring the slip sheet is intact can also prevent air leakage and maintain thermal performance. Addressing any issues with the felt paper or synthetic underlayment promptly is important, especially if there’s water damage or any degradation of the roofing material. If homeowners find that the adhesive backing on self-adhering membranes has lost its strong bond, it may be time to consult a local roofing contractor to assess the situation.
Staying proactive with these maintenance tasks can significantly extend the life of the roofing system and satisfy local building codes.
FAQ
What materials should I put under metal roofing?
Place a solid plywood or oriented strand board (OSB) deck beneath metal roofing for support. Use a vapor barrier, such as felt paper or synthetic underlayment, to prevent moisture buildup. Additionally, consider insulation materials like rigid foam or fiberglass batts for energy efficiency.
Do I need to use a vapor barrier under metal roofing?
Yes, using a vapor barrier under metal roofing is advisable, especially in humid climates. For example, a polyethylene sheet can prevent moisture buildup that could cause corrosion. Ensure the vapor barrier is installed correctly and extends beyond the roof edges for maximum effectiveness.
Is underlayment required for metal roofing installations?
Yes, underlayment is recommended for metal roofing to enhance waterproofing and insulation. Use a high-quality synthetic underlayment or felt to prevent moisture buildup. Check local building codes, as some areas may require it for warranties and durability.
What type of insulation can I use under metal roofing?
You can use foam board insulation, reflective radiative barriers, or spray foam insulation under metal roofing. For example, EPS or XPS foam boards provide excellent thermal resistance, while a radiant barrier reflects heat away. Ensure proper ventilation to prevent moisture buildup and improve energy efficiency.
Can I install metal roofing directly onto plywood without underlayment?
No, it’s not recommended to install metal roofing directly onto plywood without underlayment. Use a synthetic or asphalt felt underlayment to protect against moisture and provide insulation. For example, a combination of OSB plywood followed by a durable underlayment can enhance the roof’s longevity and performance.
