Does Having Roof Underlayment Matter in the Greater Seattle Area? 

Are you researching the components of a roof and feeling skeptical about the value of roof underlayment? Are you curious about what roof underlayment is and why it even matters if you have it on your roof?

At RoofSmart, we do hundreds of roof replacements every year. During each of those projects, we make sure to include underlayment as a base layer on the roof. It is a vital protective layer for the roof, especially in a rainy area like Seattle. But, before the roofing job even begins, we take our customers through our detailed proposal.

Customers often ask why roof underlayment matters and if they even need it. We make sure to educate them on the benefits of roof underlayment and explain their options so that they can choose the one that best fits their needs and budget.

In this article, you’ll learn why it is important to have roof underlayment as an added barrier of protection on your roof. By the end, you’ll understand why roofing code requires the use of underlayment and how it can be extra beneficial during a roof installation in the Greater Seattle area.

What is roof underlayment?

Even though it is a vital piece of your roof, underlayment is not discussed very much. Many homeowners do not know about it.

Underlayment is a protective layer of synthetic material that lays on top of the roof deck. Once it is applied, the shingles get installed on top of it. Underlayment can be made of different materials, but the most common kind is synthetic. Its job is to keep water off of the roof deck.

Why is roof underlayment necessary?

Roof underlayment is a code requirement for roofers to install in the Seattle area, so you cannot choose to exclude it. You also need it in order to get warranty coverage for your roof. But, roof underlayment can make a huge difference when it comes to protecting your roof.

Here’s how:

During installation

Underlayment protects the roof deck from moisture infiltration, ensuring its durability during and after the roof installation.

It creates a barrier for the wooden roof deck during rainy conditions so that the plywood does not absorb any moisture. This is necessary because water can cause serious damage to your roof.

Having a wet roof deck can lead to mold, which is a risk to your health. It can also cause the wood to rot, which can lead to structural damage to your roof. The last thing you want after paying for a new roof is to spend thousands more on fixing issues that could’ve easily been prevented!

It also contributes to safe working conditions by providing a more stable walking surface.

After installation

Once the shingles are on the roof, they are the main protective barrier for the roof. But if there was ever a situation where water got underneath the shingles, then the roof underlayment would still help to keep the water out.

For example, your shingles might blow off in a windstorm, but your roof’s underlayment would still help to protect it.

Ice dams

Underlayment can help protect your roof if ice dams form. Ice dams happen when the water from melted snow refreezes on your shingles. This can create a barrier that prevents water from flowing off the roof, which can cause it to pool up on the shingles and get underneath them.

If this happens, your roof’s underlayment will be there to help protect your roof until a roofer can fix the problem.

Why is roof underlayment important for roofing jobs in the Seattle area?

The Greater Seattle area is well-known for its extensive rainy season. Rain is not ideal weather for roofing, but underlayment makes it possible to keep going.

If your roof deck were to get wet during the installation of your new roof, it could lead to issues later on (such as mold or rotting wood). This is a concern when it is raining, but underlayment solves this problem because it is meant to keep moisture out.

Your roofing contractor will divide your roof into sections and quickly install underlayment right after the old shingles have been removed. And, you can install shingles on wet underlayment without causing any problems to your roof.

This process can be done in light rain or rainy conditions. However, in heavy rain, it is not safe for roofers to work, so they’d have to wait until the rain slows down or stops.

So, depending on how rainy it is, your roof can stay dry with the use of underlayment. Without underlayment, your roof wouldn’t be properly protected from the rain and you would have to wait even longer to get your roof installed.

How do I know which type of underlayment is right for my roof?

There are three types of underlayment:

• Felt: This underlayment is made of paper and asphalt. It is the most affordable option and has been around the longest. It is meant to be water resistant, but it will absorb water and wrinkle. It still keeps water off of the roof, though.
• Synthetic: This underlayment is made of various polymers woven together, making it water-resistant. This is the most commonly used option in the Greater Seattle area.
• Self-adhered: Instead of being nailed or stapled down, this type of underlayment sticks right to the roof. It is made of asphalt and rubber, making it a great option for water resistance. It’s also designed to be less slippery to walk on.

When choosing your preferred type of roof underlayment, you need to consider your preferences and the environment you live in.

If you’re looking for the most affordable option, then you should consider felt underlayment. It is the cheapest option, but if it’s installed in the rain it can wrinkle and make the roof uneven.

Typically, homeowners in this area want good water resistance at a reasonable price, which is why synthetic underlayment is most commonly used. It offers the necessary protection for your roof while also being durable.

If you’re looking for the standard option that will get the job done, then synthetic underlayment is a good option for you.

If you want to be extra cautious about preventing water from reaching the roof deck, then adhesive underlayment might be a good option for you. It sticks to the roof instead of being nailed on, which drastically reduces the amount of times it gets pierced with nails.

Why Roof Underlayment Matters: Protect Your Roof in Seattle’s Rain

When it comes to roofing in the rainy Seattle area, underlayment isn’t just a bonus—it’s a necessity. Whether during installation or long after your shingles are in place, underlayment provides a critical layer of protection against moisture, mold, and structural damage.

No matter your choice, underlayment plays a vital role in protecting your roof and home from Seattle’s relentless rain.

In order to help you get the best protection for your roof’s unique needs, it’s important to find a qualified contractor who can help you choose between the different types of underlayment.

Not sure how to find a qualified contractor? We can help! Read our article “How Do I Know If A Roofing Contractor is Qualified?” to guide your search for a trustworthy, experienced roofing contractor.