All About Asphalt Roof Underlayment When Replacing a Roof
The Importance of Asphalt Roof Underlayment
Your roof is a system of components that work together to keep your home warm and dry. One critical element is asphalt roof underlayment.
There are many parts to your roof beyond the shingles. Asphalt roof underlayment sits between the shingles and the wood roof deck. Underlayment provides additional insulation to the home while acting as a waterproof barrier to prevent moisture from entering your attic. It's also one of the most overlooked parts of your roof.
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Like your shingles, underlayment needs to be replaced semi-regularly based on the condition of your roof. For decades, asphalt roofing underlayment was only available in one type called asphalt-saturated felt. Today, three types of underlayment are available – asphalt-saturated felt, rubberized asphalt, and synthetic underlayment.
Learn about the three types of asphalt roof underlayment and which best stand up to our Illinois weather extremes.
The Three Types of Roofing Underlayment
Roof underlayment is one component of a roofing system. It sits between the decking and asphalt shingles to provide an additional layer of protection. The underlayment acts as a waterproof barrier that keeps moisture out of your home. Thanks to modern manufacturing techniques, three different types of underlayment are available today. Each has its own set of pros and cons.
Asphalt-Saturated Felt
This underlayment is best for inexpensive roof repairs and is typically used for asphalt shingles, slate, and tile roofs.
Key characteristics: Asphalt-saturated felt is water resistant, not waterproof, and comes in two standard weights – 15 pounds and 30 pounds.
This is the oldest type of roofing underlayment. Similar to tar paper, the waterproofing ingredient is asphalt instead of tar. Asphalt-saturated underlayment has been used for decades to provide moisture resistance and insulation. Also known as roofing felt or felt paper, it is the most affordable option. Asphalt-saturated roof underlayment remains popular and can improve the durability of the roof deck to protect against impact damage from airborne debris, like tree branches.
Rubberized Asphalt
This premium roofing protection offers the best leak prevention and stands up to extreme temperatures.
Key characteristics: Rubberized asphalt is waterproof, self-adhering and self-healing. It is patchable and great for variable climates.
Rubberized asphalt is a top-quality product that provides the highest level of waterproofing. It is used around leak-prone areas, like eaves, valleys, vents, chimneys, and skylights. It helps to prevent water damage before it can become problematic. Typically made from rubber polymers and asphalt, each manufacturer varies the composition of their products.
This variability allows the manufacturers to alter the product to improve waterproofing, fiberglass reinforcement, or sound absorption. If it is ever damaged, it can be patched. However, the biggest drawback to this type of underlayment is the cost. It is the most expensive option. It is also known as self-adhering because it has an adhesive backing that sticks directly to the roof deck. This underlayment can also expand and contract without cracking or breaking, making it an excellent choice for areas that experience extreme temperature variations.
Synthetics
Synthetics offer durability, tear resistance, and mold resistance.
Key Characteristics: It is highly heat-tolerant, recyclable, goes on quickly, is easy to walk on, and is reliably water-resistant.
This is the most recently developed underlayment. Synthetics are made from woven or spun polyethylene or polypropylene to improve durability and tear resistance compared to saturated asphalt. This type of underlayment is priced between asphalt-saturated felt and rubberized asphalt. If you are looking for a less expensive option with the durability of rubberized asphalt, synthetics are a good choice.
While synthetics are primarily designed for durability and tear resistance, they are also good for waterproofing but don't quite reach the same level as rubberized asphalt. If your home is prone to mold, synthetic underlayment is recommended because it repels water and is inert to mold. While it is the newest entrant, synthetic underlayment has been gaining popularity since its introduction.
Choosing the Right Asphalt Roof Underlayment
To determine which roof underlayment is best for your home and location, you must consider several factors, including climate, durability, water resistance, and cost. Asphalt shingles pair well with rubberized asphalt and asphalt-saturated felt.
Here in Illinois, we experience hot summers, cold winters, and lots of wind, rain, and snow. In our region, synthetics and rubberized asphalt will stand up best to these conditions.
Durability
If durability is your goal, opt for synthetic roof underlayment. Its tear resistance makes it the most durable choice. However, if waterproofing is important, spend a little more on the rubberized asphalt. Rubberized asphalt also lasts longer than felt or synthetics. On average, it lasts for 25 to 35 years.
Cost
If cost is a factor, asphalt-saturated underlayment is the most affordable. Synthetic roof underlayment is next, and rubberized asphalt is the most expensive.
Your roof is critical for keeping your home safe, dry, and comfortable. It is crucial to keep your roof maintained. Your best option when choosing roofing components is to discuss your choices with your contractor. They will understand the local weather and your home's style and aesthetics and can direct you to the best option to meet your needs.
If you live in the Wilmette, Illinois area, give the experts at Lynch Roofing a call at (847) 217-0004. We can help keep your roof in top shape with semi-annual inspections. Let us find and repair issues before they become critical. Our team will keep your roof ready to meet the challenges of our Illinois weather and up your home's curb appeal!
