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What Is A Roof Underlayment & Its Different Types

Posted on April 24, 2024

Estimated Reading Time : 6 Min.

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What Is A Roof Underlayment & Its Different Types

Roofs don’t just serve a decorative function, they are the home’s primary protectors against weather elements like rain, wind, heat, and more. Amidst these layers of defense  is the roof underlayment.

Often forgotten about, the roof underlayment is not just a layering material, it’s a unique component that has other roles beyond aesthetics or adhesive functionality. In this blog post, we’ll explore the importance of underlayment in roofing, the different types available, and how to choose the right one for your needs. 

By the end of this comprehensive guide, you’ll have a clear understanding of everything you need to know about roof underlayment. 

What is Roof Underlayment?

Roof Underlayment

Roof underlayment, also known as roofing felt or tar paper, is an often overlooked but critical component of a well-functioning roofing system. Essentially, the underlayment acts as a barrier between the rooftop and inner components of your building. It provides an extra level of protection, shielding your home from any weather conditions that could potentially cause damage.

In general, the underlayment serves as a secondary waterproofing layer installed directly onto the roof deck before the final roofing materials are added. Ask any professional roofer, “Is roof underlayment necessary?” and you’ll receive a resounding “Yes!” The purpose of roof underlayment extends beyond just water resistance, it adds insulation, prevents leaks, and protects against mold growth.

The function of the roof underlayment isn’t limited to acting as simply a buffer—it provides numerous additional benefits which I’ll get into later on in this article. 

Types of Roof Underlayment

In this section, we’ll examine four types of roof underlayment: asphalt-saturated felt, synthetic, rubberized asphalt, and specialty underlayments. 

1. Asphalt-Saturated Felt Underlayment

Asphalt-Saturated Felt Underlayment
Source : homedepot.com

This has been the long-standing roof underlayment option in the roofing industry. Comprised of an organic or fiberglass substrate saturated in asphalt, this type of roof underlayment prioritizes durability. 

Despite being somewhat overshadowed by synthetic underlays these days, asphalt-saturated felt underlayment still prevails on the market because of its exceptional water resistance and affordability. However, bear in mind that this roof underlayment is not waterproof – meaning it may not hold up well against extreme weather conditions or long-term exposure to moisture.

Related: Synthetic Underlayment vs. Felt Underlayment: Which Is Right For Your Roof?

2. Synthetic Roof Underlayment

Synthetic Roof Underlayment
Source : homedepot.com

This alternative roof underlayment type represents innovation in the roofing industry. They offer lighter weight and remarkable strength against tears and wear. Synthetic roofing underlayments are manufactured from woven polymers, an engineered material that provides enhanced protection against the elements.

Polypropylene and polyethylene are common types, and have impressive longevity and outright toughness despite having thinner profiles than traditional felt products. They are also equally crucial for their resistance to UV rays, which ensures their functionality isn’t compromised if left exposed for prolonged periods during a roofing job. 

However, it is worth noting that synthetic roof underlayments are also not without their flaws and drawbacks. Read our comprehensive blog post for more information: 7 Common Problems With Synthetic Roof Underlayment 

3. Rubberized Asphalt Underlayment

Rubberized asphalt underlayments are manufactured by integrating rubber polymers with asphalt materials for more elasticity and better sealing qualities around nails. As a result, these underlayments offer superior waterproofing, eliminating the chance of accidental leaks.

In addition, this type of underlayment generally features a sticky backing that adheres better to the roof deck—thus providing wind resistance. One thing you need to know is that rubberized asphalt underlayment comes with a somewhat premium cost tied to its elevated performance.

4. Specialty Underlayments (Ice and Water Shields)

For homes situated in colder regions where ice dams can become problematic, specialty roof underlayments like ice and water shields are a great option. What sets them apart is their adhesive nature, which forms a strong barrier directly on your roof – repelling water and preventing any seepage into the roof deck due to ice melt.

Boasting superior stickiness, ice and water shields can be installed onto eaves, valleys, and other vulnerable areas, forming a shield against water infiltration. 

Features And Innovations of Roof Underlayments

Roof underlayments are much more than just an extra layer added to a roofing system. They have advanced significantly and now incorporate many innovative features designed to provide superior protection. These aspects include water, heat, and UV resistance, as well as algae and mildew resistance.

1. Water Resistant vs. Waterproof

One of the most significant differences between various types of roof underlayment lies in their ability to resist water versus being waterproof. While they may appear identical at first glance, there is a big difference between the two. 

Water-resistant underlayments, typically made from asphalt-saturated felt or synthetic materials, can withstand a fair amount of moisture without getting damaged. However, if they remain wet for an extended time, water will inevitably infiltrate.

Also Read: How Long Can Roof Underlayment Be Exposed?

On the other hand, waterproof underlayments such as rubberized asphalt offer complete protection against water damage. Now you might be wondering, “Is synthetic roof underlayment waterproof?” The answer is yes, certain types of synthetic underlayments exhibit excellent waterproofing qualities, which protect your roof during severe weather conditions or accidental leakage.

2. Heat and UV Resistance

Advancements in technology have also enabled modern roof underlayment materials to resist better heat and UV rays from the sun. For instance, some high-end synthetic roof underlayments feature specially formulated fibers that reflect sunlight away from your rooftop. 

This reduces overheating – consequently lowering energy costs – while also extending your roof’s lifespan by avoiding premature degradation due to UV exposure.

3. Algae and Mildew Resistance

Algae and mildew growth on roof underlayments is a big concern among homeowners. These microorganisms can lead to unsightly discolorations on your roof and, on a more serious note, cause structural damage over time. 

Fortunately, some innovations in the industry successfully solved this problem. Some cutting-edge synthetic underlayments feature algae-blocking agents incorporated directly into their material composition. These chemical elements prevent algae and mildew spores from adhering to the underlayment. This ensures that your roof’s aesthetics and longevity are uncompromised. 

How To Select The Right Roof Underlayment For Your Needs 

When choosing the right underlayment for your roof, give thorough consideration to all the types of roof underlayments. The decision you make can significantly impact your home’s durability and resilience against harmful environmental factors over time.

1. Climate Conditions In Your Area 

The climate in your area is one of the most crucial aspects to consider when it comes to selecting an ideal roof underlayment. Your regional weather dictates how well your chosen product will perform, especially in adverse weather conditions. For instance, regions prone to heavy precipitation or high humidity levels might necessitate waterproof underlayments like rubberized asphalt materials. 

On the other hand, dry or hot climates may need more reflective roof underlayments that help manage heat absorption better. Moreover, areas susceptible to strong winds or hail may need a sturdier roofing underlayment that is more compliant with local area building codes. 

2. Roof Type and Material Compatibility

Another important factor to consider is your roof’s type alongside its main construction material. Different types of roofing materials and shingles require different types of underlayments.

For example, traditional asphalt shingles work best with asphalt-saturated felt or synthetic underlayments. Metal roofs generally require specially designed underlayments for metal roofs that can handle high surface temperatures without developing degradation problems.

3. Durability and Life Expectancy

Nobody likes to replace their roofing underlayment regularly—it’s labor intensive, disruptive, and expensive. Therefore, it is important to select an underlayment with a lifespan comparable to your roofing material. 

While traditional asphalt-saturated felt was once highly popular due to lower upfront costs and satisfactory performance in many climates, synthetic options (despite being relatively more expensive) have increasingly become preferred choices because they are more resilient against adverse conditions over time.

Roof Underlayment Installation Mistakes To Avoid

Everyone makes mistakes, but when it comes to roof underlayment installation, some errors could cost you dearly.

  • One of the common pitfalls is failing to follow the manufacturer’s instructions. Each type of material has its unique specifications, and ignoring them might lead to roofing problems or even product failure.
  • Improper overlapping often leads to leaks over time due to seepage rather than directing moisture away from the house. 
  • Avoid installations without appropriate safety measures, accidents can happen when we least expect them while performing roofing tasks.

Closing Thoughts 

When making this decision, ask yourself: What is the best roofing underlayment according to my roofing needs? A product that lasts longer might cost more initially, but it could save you from frequent replacements later on.

Ultimately, selecting the perfect roof underlayment involves careful consideration of the above-mentioned factors and understanding how they impact your requirements. A wise choice now can safeguard your home structurally while providing peace of mind for years to come. 

Contact The Expert Roofers In Tulsa, OK, For Your Roofing Needs

Are you considering installing a new roof or replacing the existing materials on your roof? Contact the skilled and experienced roofers at A. Fricker Roofing and Waterproofing in Tulsa, OK. The roofers at the company can proficiently handle any roofing project, be it a new roof installation or a complete roof replacement. Give us a call today at (918) 402-7167 and speak with one of our expert roofers.