Roofing underlayment is an unsung hero in home protection. It sits between the roof sheathing and shingles, providing a critical extra barrier against the elements—keeping your home dry, comfortable, and protected from leaks and harsh weather.
In this article, we’ll review types of roofing underlayment and why you need it.
What Are the Most Common Types of Roofing Underlayment?
When choosing roofing underlayment, you have several options. Each underlayment type offers unique benefits and fits different roofing needs and climates. Here’s a breakdown of the most common types of roofing underlayment:
Synthetic Roofing Underlayment
In recent years, professional roofers have increasingly used synthetic roofing underlayment. This option consists of a synthetic basemat saturated in asphalt, giving it excellent water resistance. Many manufacturers also add fiberglass to increase tear resistance and stability.
Higher-quality synthetic underlayments often include a coarse or scrim-woven material reinforcement, which provides slip resistance in wet conditions. Synthetic underlayment stands out for its flexibility, durability, and mold resistance. Its lighter weight compared to rubberized asphalt underlayment makes it an excellent option for heavy roofing materials like concrete tiles.
Synthetic underlayment lasts longer and resists UV exposure and fungal growth better than other options—it’s a long-lasting solution that stands up to environmental challenges. Its lighter composition also makes installation easier and reduces labor costs.
Asphalt-Saturated Felt Underlayment
Asphalt-saturated felt has long been the go-to choice for roofing underlayment. This type of underlayment, often called roofing felt, felt paper, or tar paper, is made from polyester, cellulose (natural plant fibers), and asphalt (bitumen).
Roofers often choose asphalt-saturated felt for its flexibility and water-resistance, making it ideal for metal roofs. Contractors secure it to the roof deck with staples, fasteners, or plastic caps.
Asphalt-saturated underlayment comes in two thicknesses: 15-pound and 30-pound. The 30-pound variety resists damage better during installation and lasts longer, though it’s more difficult to install.
Asphalt-saturated felt resists water, but it doesn’t make the roof waterproof. This makes it better suited for steeply sloped roofs where water runs off quickly. Avoid this underlayment for flat roofs, where standing water, which may penetrate the roof decking, tends to collect.
Rubberized Asphalt Underlayment
If you live in an extreme climate, consider rubberized asphalt underlayment. This option offers superior waterproofing, UV resistance, and flexibility. Though it costs more and weighs more than other options, it goes the extra mile to protect your home in severe weather conditions.
Rubberized asphalt underlayment comes with a self-adhesive back and a protective membrane, creating a tight roof seal. Roofers often apply it at the eaves to prevent water damage along the edges of the roof deck. They also apply it to low areas, such as roof valleys and around protrusions, to reduce the risk of leaks.
What Are the Benefits of Roofing Underlayment?
Here are some of the key benefits of installing quality roofing underlayment:
Compliance With Building Codes
Local building codes may require specific types or quantities of roofing underlayment. Consult with a roofing contractor to make sure your choice of underlayment complies with applicable construction regulations.
Enhanced Fire Safety
Roof shingles alone often don’t meet Class A fire ratings, which can put homes at risk. Installing roofing underlayment that meets industry standards and building codes helps a roof achieve crucial Class A fire rating requirements.
Moisture Barrier and Protection Against Water and Ice Damage
Rain and snow can get trapped under shingles without proper underlayment, leading to water damage, mold growth, wood rot, and leaks. Water-resistant underlayment seals the roof frame, making sure water drains off the roof instead of collecting and seeping through.
Underlayment also protects against ice and snow dams, which strain the roof structure and increase the risk of water damage. By providing protection that shingles alone can’t offer, roofing underlayment helps maintain your home’s integrity.
Uniform Surface
Roof decks aren’t always perfectly flat or straight, making achieving a uniform look with shingles challenging. Roofing underlayment creates a smooth, even surface for shingle installation, letting roofers create a polished “picture framing” effect rather than a patchy or uneven appearance.
Weather Protection
Shingles are the first line of defense against the elements, but roofing underlayment adds extra protection. If strong winds lift or blow off shingles, the underlayment keeps water out and prevents damage to the roof deck.
Even when shingles remain intact, water sometimes finds its way underneath. Roofing underlayment protects against rain, ice, and snow, reducing the roof deck’s risk of rot and leaks.
Choosing the Right Roofing Underlayment
When choosing roofing underlayment, take the following factors into account:
Climate
Your local climate plays a big role in determining the best underlayment for your roof. If you live in an area with heavy rainfall or frequent storms, a highly water-resistant option like synthetic or rubberized asphalt underlayment is a good choice. Drier climates do well with asphalt-saturated felt.
Roof Pitch
The slope of your roof also matters. Steeper roofs benefit from flexible underlayment options, while flatter roofs need materials with strong water resistance.
Roofing Material
Your roofing material should influence your choice of underlayment. For instance, metal roofs pair well with synthetic underlayment because of its durability and heat resistance.
Budget Considerations
A tight budget might affect your choice of underlayment. Weigh the initial cost against long-term benefits and potential savings on future repairs.
Professional Recommendations
Consult a roofing contractor for expert advice on the best underlayment for your home and region. Professionals offer insights based on local building codes, climate conditions, and their experience with different products.
What is the Roofing Underlayment Installation Process?
While professionals usually handle underlayment installation, understanding the process helps homeowners make informed decisions. Here’s an overview of the steps:
- Preparation: Clean and inspect the roof deck for damage or weak spots to allow for a smooth and effective underlayment application.
- Application: Start at the bottom edge and secure the underlayment to the roof deck, working upward. This method provides proper water shedding.
- Overlap: Overlap each subsequent row with the previous one to guarantee full coverage and water resistance.
- Sealing: Apply sealant in water-prone areas such as valleys and around chimneys for extra protection.
- Ventilation: Provide proper ventilation to prevent moisture buildup between the underlayment and the roof deck, prolonging the lifespan of both.
Maintenance and Longevity
Proper installation and maintenance significantly extend the life of roofing underlayment. Here are some essential maintenance tips:
- Regular Inspections: Schedule roof inspections annually and after severe weather events to catch issues that might become significant problems.
- Prompt Repairs: Address problems right away to prevent water damage and maintain the underlayment’s integrity.
- Ventilation: Properly ventilate your attic to prevent moisture buildup that could compromise the underlayment over time.
- Replacement: When replacing your roof, check the condition of the underlayment. If necessary, install new underlayment for continued protection and to maximize the new roof’s lifespan.
Final Thoughts About Roofing Underlayment
Roofing underlayment is a critical component of your roof, protecting your home from the elements. By understanding the various types of underlayment and their benefits, you can make informed decisions to keep your roof in top shape.
Investing in high-quality roofing underlayment pays off in the long run with fewer repairs, better energy efficiency, and improved home protection. Work with reputable roofing professionals and choose the best materials to keep your home safe from whatever nature throws your way.
