Roof underlayment plays a vital role in the overall structure and stability of a roof. Installed just between the shingles and the sheathing, it provides your house a second layer of protection from outside elements, like wind, rain, and snow. Although not always necessary, this extra barrier prevents premature leaks, mold, and rot from damaging your home’s interior.
Like any other roofing material, underlayments come in different shapes, sizes, and prices. So, if you’re shopping for the best roof underlayment and not sure which type or brand to choose, you’ve come to the right place.
This guide reveals the best roofing underlayment to buy in 2022.
The Best Roofing Underlayments
1. Best Underlayment for Metal Roof
This underlayment is primarily designed for use with shingle roofs. But you can also be used with metal roofs to provide a better-looking roof without wrinkles.
FeltBuster® Synthetic Roofing Felt has earned the Good Housekeeping Seal and is considered one of the best roofing underlayments on the market.
It’s made of tough synthetic material that is virtually untearable and doesn’t absorb moisture or become brittle or leach oils. It also has excellent UV protection (up to 90 days) and offers a lifetime limited warranty.
When installing this underlayment, you don’t have to worry about it laying flat or having any adhesion problems. Its surface is up to 30° cooler than typical black asphalt felts even after being left exposed to direct sunlight.
Since it’s lightweight, measuring (250 ft by 4 ft), you’ll have ample time laying and will give you total coverage of 1000square feet. And it also comes with an adhesive strip and overlap film to join up additional rolls.
It’s always important to ensure that your underlayment is durable enough, especially if it’s going under a metal roof. Since GAF FeltBuster High-Traction is made of non-asphaltic polypropylene, it lasts longer than conventional felts. In addition, the company backs it up with Lifetime limited warranty when installed on Lifetime Shingle roofs.
Pros:
- Long-lasting
- Helps provide increased traction versus typical asphalt felts
- Resists tearing and will not absorb moisture, become brittle, or leach oils
- Lies flatter without wrinkling
- Cooler to work on
- A lifetime warranty is offered if installed on lifetime shingle roofs.
Cons:
- It’s expensive
What is an Underlayment?
Roof underlayment is a thin layer of material installed on the roof deck. It’s made of fiber, felt, rubber, or foam and helps cushion, sound absorption, insulation, and reduce wear on your roof.
Is Roof Underlayment Necessary?
In some cases, no, roof underlayment isn’t necessary. Some buildings go without. However, roof underlayment provides an additional layer of protection you’ll be thankful for when bad weather hits.
It protects the roof deck from damage and prevents outside leaks from heavy rain and snow. Likewise, it safeguards your roof from high winds, should your shingles tear away from the wind’s pressure.
More importantly, it extends the life of your roof. Without it, your roof is susceptible to warping, mold growth, leaks, and other roof-related damage, resulting in an increased cost of roof maintenance. So why go through the hassle when you can prevent it altogether?
Most building codes and home insurance policies require homeowners to install roofing underlayment and roof covering for the overall safety of the structure.
The same is said for shingle manufacturers, as they require roof underlayment as part of their warranty. Without it, you won’t be able to claim what you paid for.
3 Common Types of Roof Underlayment
Roof underlayment comes in three basic types: asphalt-saturated felt, non-bitumen synthetics, and rubberized asphalt. Each type comes with its advantages and disadvantages.
Asphalt-Saturated Felt
Asphalt-saturated felt, also known as felt paper or tar paper, is the oldest and second-most popular type of roof underlayment after non-bitumen synthetics. It’s typically made by saturating a combination of asphalt, bitumen, cellulose, and polyester with an organic mat or paper.
Thanks to its innate strength and water resistance, asphalt-saturated felt adds additional protection against hailstone impact, large tree branches, airborne debris, and the like. It’s the most affordable of the three roof types.
This type of underlayment comes in two standard weights: no. 15 felt (15 pounds per hundred square feet), and no. 30 felt (30 pounds per hundred square feet).
No. 15 asphalt-saturated felt is suitable for most standard-pitched roofing jobs. It’s relatively durable and not as pricey as no. 30, making it an excellent economical choice for standard-roof owners.
However, no. 30 provides double the strength and performance of no. 15. Since it’s way thicker than no. 15, it’s best used for steep-pitched roofs and other non-standard roof types. It’s also ideal for environments that experience a lot of heavy snow and rain, as it has sufficient thickness to prevent leakage and mold damage.
Pros
- Provides decent protection against rain, snow, and ice
- Protects roof deck during the installation process
Cons
- It doesn’t come with UV protection
- Poor quality underlayment absorbs water, therefore lessening its longevity
- It isn’t as durable as its counterparts; may lose some of its integrity over time
Non-Bitumen Synthetic Felt
Non-bitumen synthetic felt, otherwise known as synthetic felt, is the most commonly used type of roof underlayment for commercial and residential properties.
It’s quite similar to asphalt-saturated felt, except it’s stronger and more water-resistant. Its basement is saturated with asphalt and fortified with a mix of fiberglass and layers of finely woven polymer.
Since non-bitumen felt is almost entirely made of synthetic material, it’s anti-fungal and UV-resistant. For this reason, this type of roof underlayment withstands environmental exposure with little to no effort. It also makes it more durable and lighter than other underlayments.
High-quality synthetic felt often features anti-slip coatings that prevent water from penetrating the roof’s primary material. It also makes it easier for individuals to safely walk on the material’s surface during installation and repair.
Pros
- Exceptional strength and elasticity
- Water-resistant
- UV and fungal growth resistant
- Tear-resistant
- Incredibly lightweight
- More coverage per roll, reducing ladder trips during installation
Cons
- Fairly expensive
- Almost always requires professional installation
Rubberized Asphalt
While it has asphalt to its name, rubberized asphalt has little to no asphalt content. If anything, it’s mostly made of rubber polymers known as ethylene propylene diene monomers.
Rubberized asphalt is the most expensive type of roof underlayment. It has all the advantages of asphalt-saturated and non-bitumen synthetic felt but at a steep price.
Alongside its premium material, rubberized asphalt is the easiest to install. Thanks to its peel-and-stick installation, there’s no need to attach it with nails and staples to the roof.
Peel the plastic protection and place it in the desired space. Its rubber-like quality makes it self-sealing, allowing it to close well around fasteners.
Like non-bitumen synthetic felt, rubberized asphalt is best suited for areas that experience extremely hot and cold weather. This type of underfelt won’t damage your roof deck because it’s so durable even when exposed for extended periods. It can be exposed to harsh weather elements for 180 days with little to no adverse effects.
Rubberized asphalt comes in a variety of types. Some are reinforced with fiberglass to add an even thicker layer of durability. Others have polyethylene or polyester on the underlayment’s upper surface for non-skid and weather-resistant purposes.
You’ll also find mineral polymer-modified coatings that resist heat to 300° F without damaging the adhesive.
While it’s the most expensive, the benefits certainly outweigh the costs. If budget isn’t a concern, rubberized asphalt is the ideal choice for you.
Pros
- 100% waterproof thanks to its high rubber content
- UV- and mold-resistant
- Withstands high and low temperatures
- It lasts much longer than felt, and synthetic felt
- Easy to install
- lack of maintenance requirements
Cons
- High cost
- Some rubberized asphalt underlayment doesn’t comply with building codes
Factors to Consider When Buying Roof Underlayment
As you can see, some underlayments are more durable and waterproof than others. In most cases, rubberized asphalt underlayment is the best choice. However, this type of underlayment is either too expensive or scarcely available.
Here are some factors to consider when buying roof underlayment for your home.
Roof Material
Most underlayment types work well with a variety of roof materials, with one exception: metal roofs.
Metal roofing outlasts many other roofing types, which is why it’s among the most popular roofing materials on the market. It’s impact-resistant, doesn’t rust or crack, and can sustain wind gusts of up to 140 miles per hour.
However, metal roofing has certain qualities that affect the effectiveness of roof underlayment. As it’s mostly made of metal, metal roofs heat up quite fast and have little to no permeability. For this reason, a metal roof’s underlayment must be both breathable and water-resistant.
Asphalt-saturated felt is much more porous than non-bitumen synthetic, but it doesn’t have the best water protection. Additionally, it doesn’t come with UV protection qualities.
Non-bitumen synthetic underlayment is much more suitable for metal roofing because it provides up to 30 degrees cooler surface than asphalt-saturated felt. It also has excellent UV protection.
Weather Climate
Your area’s climate determines the best underlayment type for your home.
If you live in a place with a hot, sunny climate, like Florida or Texas, you need a UV-protected underlayment like non-bitumen or rubberized asphalt.
If you live in an area with frequent rain and snow, rubberized asphalt is your best option.
Asphalt-saturated felt is more than suitable for areas with a decent year-round climate, like California and South Carolina.
Roof Structure
The structure of your home is also worth considering when choosing a roof underlayment.
Asphalt-saturated felt is best used for standard steep-slope roofs, shed roofs, Dutch roofs, and mansard roofs because it allows water to run off the side easier.
Flat roofs, m-shaped roofs, butterfly roofs, and oddly shaped roofs need water-resistant underlayments like non-bitumen and rubberized asphalt. This is because water tends to pool on top of these roofs.
Shake Roofing
Shake-style roofing comes in asphalt, fiberglass, and wooden varieties, and with all three, non-bitumen synthetic underlayment is the ideal choice.
Shake-style roofing, as the name suggests, is a roof made from thousands of individually applied shingles.
Asphalt-saturated felt, and rubberized asphalt degrade over time, making them unsuitable for shake roofing.
Synthetic underlayment excels in longevity, which is why it’s the recommended option. Compared to the other two, it can easily last 30 to 40 years with inspections. On the other hand, Asphalt-saturated felt and rubberized asphalt can only last 15 to 25 years.
Signs of Damaged or Old Underlayment
If installed properly, roof underlayment can last upwards of 25 years. However, improper installation, poor maintenance, and severe weather conditions can decrease the life of roof underlayment.
Here are some of the biggest signs of a damaged or old underlayment:
Leaks
The primary purpose of roof underlayment is to prevent water from leaking into your home after periods of rain and snow. If you notice water leakage coming from your rooftop, this might be a sign that your underlayment needs to be replaced.
Sagging Roof Deck
Excessive water or snow build-up typically causes sagging roofs. This is why old or damaged underlayment with improper water ventilation may cause your rooftop to sag unevenly. This issue is prevalent with roofs with low slopes.
High Energy Bills
If you’ve noticed a gradual increase in your energy bills, this might be due to old or damaged underlayment.
Alongside weather protection, underlayment adds an extra layer of insulation to your home. So if your underlayment is damaged, it’s only natural for your heating and cooling costs to increase.
Conclusion
To summarize, roof underlayment come in three common types: asphalt-saturated felt, non-bitumen synthetic felt, and rubberized asphalt.
Asphalt-saturated felt is ideal for standard pitched roofs and areas with decent weather conditions. It’s the most economical choice of the three underlayment types.
Non-bitumen synthetic felt is the most durable. It’s anti-fungal and UV- and water-resistant. Plus, it’s supremely lightweight.
Lastly, rubberized felt is the most weather-resistant, making it suitable for areas that experience extreme heat or cold. In addition, compared to other underlayment types, rubberized asphalt is waterproof rather than water-resistant.