What Is Roof Underlayment?
The Complete Guide To Roof Underlayment So You Can Make The Right Decision On Which UNderlayment Is Right For You!
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Roof Underlayment Basics
Why Is Roofing Underlayment Important?
Certain sections of a roof- the valley, dormer, and hips- are likely to give you roof leaks during heavy rain. Since shingles and/or metal roofs provide inadequate coverage in such areas, roofing underlayment is important to protect your home from water leakage.
Types Of Roofing Underlayment
There are three types of roof underlayment: felt, synthetic, and self-adhered. Each is structured differently and carries its own advantages and disadvantages. Your choice of roof underlayment will depend on the budget, roof design, roofing material, and local climate. Fortunately, a good roofing contractor will suggest the best underlayment for your home, so you don’t have to go through the trouble of analyzing every factor.
1. Felt Roofing Underlayment
- No. 15 felt, which weighs 15 pounds per 100 square feet of roofing. This felt underlayment is typically used for lightweight projects. However, it tears easily and tends to absorb water and wrinkle if left exposed for too long.
- No. 30 felt, which weighs 30 pounds for every 100 square feet of roofing. It’s heavier and, thus, more durable than No.15 felt.
Pros
- Felt is the cheapest underlayment option.
Cons
- Felt underlayment is quite heavy, making it harder for contractors to work with. Its weight also means that felt carries less material per roll. This leads to more trips up the ladder and more seams to cover 100 square feet of roof.
- It has a slippery surface that makes it difficult and riskier to install
- It’s prone to tearing under strain; during installation or when exposed to high winds
- Felt absorbs water and develops wrinkles when exposed to moisture. These wrinkles make it hard to lay shingles flat on the roof.
- Some roofing manufacturers require synthetic underlayment. Thus, installing felt underlayment may void your warranty.
2. Synthetic Roofing Underlayment
Pros
- Synthetic roof underlayment is tough and durable. It doesn’t tear easily, even under the boot traffic of roofers during installation. In addition, some brands of synthetic underlayment can withstand exposure to UV rays and moisture without sustaining damage.
- It’s also considerably lighter than felt roofing, making it easier and more convenient to install.
- Being plastic, it repels moisture instead of absorbing it and is resistant to mold and fungal growth.
- Synthetic roof underlayment also carries more material per roll, reducing the number of trips up the ladder roofers have to make to cover 100 square feet of roof.
- Many synthetic roof underlayment brands have slip-resistant surfaces, reducing the risk of slip and fall accidents during installation.
Cons
- Synthetic roofing underlayment is relatively more expensive than felt.
3. Self-Adhered Underlayment
In the world of roofing, self-adhered underlayment is as premium as they come. These products contain high percentages of rubber and asphalt polymers to make them water-resistant. They also have sticky undersides that adhere to the roof deck to create a waterproof seal around nails and the sun will help the sealant waterproof all nail holes leaving an impenetrable roof covering.
Pros
- Self-adhered underlayment is very durable.
- It’s the only underlayment with a 100% waterproof seal.
- It’s a self-sealing underlayment, making it ideal for sealing around fasteners.
- Self-adhered underlayment has slip-resistant surfaces that make it safer for roofers to work on.
Cons
- Self-adhered underlayment is the most expensive of the three options available.
Find Your Ideal Roofing Underlayment
Whether you’re reroofing your home or building a new one, choosing the right roofing underlayment is just as important as picking the right roofing material. So when you are deciding on your next roof and thinking about things like is a metal roof or shingles better, what thickness of roofing underlayment should I get or what types of roofing materials should I have installed, remember to go for what makes the most sense for you and your property long term.
Those that have no limit on their budget and/or live in areas with harsh winters can find the best quality in self-adhered roofing underlayment. If you want an experienced residential and commercial roofing contractor that will handle all your roofing needs, contact us today for a free consultation.
