Roofing underlayment is a necessary piece for any roofing installation project. It lays between the shingles and your roof sheathing.
The underlayment adds extra protection from the elements. Some types of underlayment are water-resistant. Others help insulate your home from heat or snow.
But before installing, you need to know the correct roofing underlayment type for your roof. We’re here to help guide you through it. In this article, we’ll be covering:
- What is a roofing underlayment
- The different types of roofing underlayment
- The pros and cons of installing one
- How to choose the right roofing underlayment type for your roof
- Budget estimations for installment
What is a Roofing Underlayment?
Roofing underlayments are typically made up of synthetic fiber or felt that sits on top of your roof deck (boards fastened onto trusses to give structure to your roof).
Throughout the years, your underlayments protect your home against the elements. That means it isn’t a permanent solution. The good news is experienced contractors can easily replace it.
Back then, you’d find only one type of underlayment—asphalt-saturated felt. However, as technology improved, several types of roofing underlayment were developed.
Types of Roofing Underlayment
You’d often find three main types of roofing underlayment that can be used on most standard roof decks. These are asphalt-saturated felt, synthetic underlayment, and rubberized asphalt.
Each type is best suited for specific kinds of shingles and use cases. Here’s a quick rundown of the underlayment’s characteristics and what they’re best used for.
Asphalt-Saturated Felt
Asphalt-saturated felt has been the go-to roofing underlayment type for years until synthetic types were made. It’s still used today. But, like everything, it does come with pros and cons.
Pros:
- Made to be water-resistant thanks to the asphalt-saturated base layer.
- Heavier variants work well against heavy hail, snow, or rain.
- Provides a good layer of seepage protection.
- Installation can be done using standard tools.
- It’s relatively inexpensive compared to most materials.
Cons:
- Weight can be an issue, especially with heavier variants.
- Although installation can be done with standard tools, it can be difficult due to its weight.
- Exposure to constant cold can cause wrinkles and cracks.
- Volatile compounds present can dissipate when exposed to heat.
- Prone to absorb more moisture when its volatile compounds dissipate.
With all things considered, asphalt-saturated felt is best used for inexpensive roof repairs and standard slate or tile shingles. Be mindful of the weight (typically 15 or 30 pounds).
Synthetic Underlayment
Most roofing professionals recommend using synthetic underlayment for your roofing. That’s because it’s lightweight, has better water and tear resistance, and has improved stability.
It’s also made with saturated asphalt, but fiberglass is added. The result is a more vital underlayment effective against harsh weather conditions and moisture buildup.
Pros:
- Lightweight compared to asphalt-saturated felt
- It is designed to be used across the entire roof deck
- It is more effective against strong winds and heavy rains.
- It lasts longer than most underlayment types.
- Better seepage barrier
Cons:
- More expensive than asphalt-saturated felt
- Requires more tools and skills to install
Synthetic underlayment is best if you want something tear-resistant, durable, and mold/water-resistant.
Rubberized Asphalt
Rubberized asphalt is the most expensive underlayment, and for good reason. With the highest percentage of asphalt and rubber polymers, rubberized asphalts are waterproof, not just water resistant.
Before installation, rubberized asphalt strips come with sticky protective membranes on the back. Once the membrane is removed, it creates a waterproof seal between the underlayment and your roof deck.
Just ensure that the roof deck is clean before installation. This covers any potential water damage or leaks following storms or heavy rains. Here are some of its pros and cons:
Pros:
- You get waterproof underlayment
- You get better heat and cold insulation than other underlayment types
- Can be exposed to the elements for up to 180 days while waiting for roofing cover
Cons
- It’s the most expensive underlayment material on the market
- Installation needs to be done by professional roofing contractors
How to Choose the Right Roofing Underlayment?
We’ve already learned the main types of roofing underlayment. Now, which one is the best fit for your home? Before investing in an underlayment, consider these critical factors:
Climate
Climate plays a huge role in the material you can get. For example, asphalt-saturated roofs are good options if you’re situated in an area with low weather fluctuations. Regions with harsh, seasonal weather changes might be better off with rubberized or synthetic underlayment.
Type of Roof
Different roof types work best with specific roofing underlayment. Here’s a quick checklist to help you identify what underlayment works best for your roof type:
- Traditional Asphalt Shingles: Rubberized asphalt and asphalt-saturated underlayment
- Slate Roof: Rubberized asphalt and asphalt-saturated underlayment
- Metal: Synthetic roof underlayment (because it’s more heat resistant)
Durability
You want an underlayment that lasts long, requires little maintenance, and needs minimal repairs. If you want something durable and tear-resistant, invest in a synthetic roof. But, if your area is prone to rain or storms, you might want rubberized asphalt instead.
Cost
Asphalt-saturated felt underlayment is the most affordable. But, also consider where your home is located. It might be cheap now, but roof repairs and maintenance can quickly stack up.
Like any other roofing material, underlayment is quoted per square foot or roofing square (100 square feet). Here’s a quick rundown of estimated costs (not including labor)
- Asphalt-saturated felt: $0.05 to $0.50
- Synthetic underlayment: $0.17 to $0.55
- Rubber underlayment: $0.55 to $0.65
Final Thoughts
Roofing underlayment is essential in any roofing installation. It adds extra layers of protection and insulation and can waterproof your home with the proper underlayment material. If you’re planning on installing or repairing roofing underlayment, consider the following:
- Choose an underlayment that works best for your climate
- Different underlayment types fit better with certain roof types
- Consider the cost of the materials
- Always ask professionals to install your underlayment