Between the plywood and tiles or shingles of your roof lies the powerful underlayment. Roofing underlayment, a thin sheet of material, acts as that extra layer of superhero protection for your home against the elements. From decades of roofing experience, we get to see both the good and the bad.
Back in the day, felt was your only option. Now, you have more options, but which underlayment is best for your roof? Here, we’ll cover the different types of roof underlayment and how to make your choice for personalized weather protection.
A Look at Roof Underlayment Types
1. Synthetic underlayment: Newer, stronger, and cost-competitive
Synthetic underlayment combines the best properties of traditional organic felt and synthetic products. When we inspect roofs that are failing or leaking, the two primary contributing factors are tears in the felt or wrinkles caused by moisture. Synthetic underlayment is wrinkle-free, even when wet, and has a high tear strength.
2. Felt underlayment: The only option until now
Because felt is a lower-cost and environmentally friendly cloth saturated with asphalt, it’s commonly used to get the job done. Although water-resistant, felt underlayment may still absorb water when exposed to moisture. Felt underlayment ranges from 15-pound to 90-pound rolls, indicating its thickness and asphalt content. Despite a reduction in today's average roll weights, they are still categorized as 15-pound, 30-pound, 40-pound, and 90-pound.
3. Rubberized asphalt underlayment (aka SBS modified)
Rubberized asphalt underlayment is made of a fiberglass sheet with recycled rubber superimposed on both sides. Its composition means that SBS-modified underlayment is very versatile and stable.
3.5 Low-E underlayment (insulation)
Low-E, also called ThermaSheet®, acts as a thermal break and reflects radiant heat. If you want to get technical about it, Low-E insulation is insulation. Low-E is used in combination with your underlayment to stop heat from getting into your house. Without it, you would need your air conditioning to expel the heat. Low-E is extremely helpful in areas where the outside temperature gets above 90 F.
Which Type of Underlayment Do You Need?
The type of underlayment that’s best for you depends on your priorities:
“I don’t want to break the bank”
If your priority is a traditional, lower-cost roofing system felt is a good option.
The pros of felt include:
- More affordable
- Extra breathability (higher perm rating)
- Satisfactory results
The cons of felt include:
- Not ideal for extreme temperatures
- Heavy, difficult to handle, and challenging to install correctly
- Prone to ripping and tearing
- Prolonged exposure to water causes the felt to wrinkle
Satisfactory installation requires the shingles to be installed as quickly as possible once the felt installation is complete. This is because if any moisture gets to the felt, the felt can wrinkle, creating an uneven roof surface that won’t last. Thanks to the newer solutions available, felt is no longer the option we recommend on most roofing systems.
“Give me the best home protection”
If you’re concerned about premium roofing protection, leak prevention, and extreme temperatures, choose rubberized asphalt underlayment.
The pros of rubberized asphalt include:
- Stable with superior tear resistance
- Strong enough to go up against extreme weather conditions
- More heat resistant than felt
- Longer lasting than felt
The cons of rubberized asphalt include:
- Higher initial cost
- Heavier than some options
- Not as much coverage per roll
With rubberized asphalt, you get what you pay for. Although it is more expensive than other options, it’s also the underlayment of choice for many homeowners due to its durability and water resistance properties. This means that you can enjoy a longer-lasting roof with proper installation.
“Lower my home’s temperature”
If your goal is to lower energy bills, prevent degradation, and lower your home’s temperature, choose Low-E underlayment.
The pros of Low-E include:
- Reduces energy usage
- Won’t heat other roof materials
- Durable and easy to install
The cons of Low-E include:
- Higher initial cost
- The need for an additional underlayment
- Lack of accessibility (it may not be available in all areas)
Low-E ThermaSheet is gaining popularity as more people realize the potential energy bill savings and extended roof life.
“I need long-lasting with the option for solar panel installation”
If you need tear resistance and mold resistance and/or want solar panels installed in the future, choose synthetic underlayment.
The pros of synthetic include:
- Durable and tear-resistant
- Thin and lightweight, can conform to complex roof shapes
- More coverage per roll
- Withstands high temperatures even under solar panels
The cons of synthetic include:
- Higher initial cost
- Lack of accessibility (it may not be available in all areas)
- Must be installed correctly for proper mold resistance
This is a popular choice for Arizona homeowners for good reason! Although it’s higher cost than traditional felt, synthetic underlayment is ideal for homeowners who want benefits similar to rubberized asphalt but also plan on solar power installation in the future.
In the long run, synthetic underlayment is cost-effective because of its durability and long-lasting nature. In other words, you get the best-of-the-best solution with the option to go solar later on.
Still Not Sure Which Type of Underlayment Is Right for You?
Other considerations — such as what materials are used for your roof system — could alter which type of underlayment is ideal for your situation.
Don’t worry about it! We’ve got you covered with a complimentary, no-obligation site evaluation where our roofing experts will look at your setup and present you with the best options for your home.
