Signs Your Roof Underlayment Needs Replacement

Your roof underlayment is a crucial, but often overlooked, component of your roofing system. It sits between your roof deck and shingles, acting as a second line of defense against moisture, wind, and other elements. Over time, underlayment can deteriorate, leaving your home vulnerable to leaks and structural damage.

At Brad’s Construction, we help Wisconsin homeowners identify and address roofing problems before they escalate. If you suspect your underlayment might be failing, here are the signs to look out for, and what to do about it.

What is roof underlayment, and why is it important?

Roof underlayment is a critical component of your roofing system, serving as the hidden barrier between your shingles and the wooden roof deck beneath. It’s typically made from one of three materials:

• • Asphalt-saturated felt (felt paper): An older standard that offers basic protection but degrades over time.
  • Rubberized asphalt: A waterproof material with superior durability, often used in high-risk areas.
  • Synthetic underlayment: A modern, lightweight, and tear-resistant material that provides better water resistance and breathability.

While shingles are your roof’s first line of defense, they aren’t completely waterproof, especially during wind-driven rain or after storm damage. That’s where underlayment comes in. It acts as a second layer of protection, preventing moisture from soaking into the plywood or OSB roof sheathing.

Without properly installed and functioning underlayment, your home may be exposed to:

• • Roof leaks from water intrusion under lifted or broken shingles
  • Rotting roof decking due to long-term exposure to trapped moisture
  • Mold and mildew growth in your attic, which can spread to insulation and framing
  • Ice dam damage during winter when melting snow backs up under the shingles
  • Reduced insulation performance, as wet insulation loses its effectiveness

Additionally, underlayment plays an important role in:

• • Fire resistance in certain roofing systems
  • Shingle longevity, by providing a smoother surface for proper shingle installation
  • Meeting building codes and warranty requirements for roof materials

Whether you're maintaining an older roof or preparing for a complete roof replacement, understanding and evaluating your underlayment is essential. At Brad’s Construction, we inspect every layer of your roof system to ensure your home stays dry, structurally sound, and energy-efficient, season after season.

Common signs your roof underlayment needs replacement

Roof underlayment problems often go unnoticed until leaks or damage begin to show. While some issues can be spotted from the ground or attic, others require a thorough inspection from an experienced roofing contractor. Here are the most common warning signs that your underlayment may be failing:

1. Persistent roof leaks

If you’re dealing with recurring leaks, especially after storms or melting snow, your underlayment may no longer be providing a watertight barrier beneath the shingles.

• • • Ceiling stains, peeling paint, or damp drywall are all signs of ongoing water intrusion.
    • Even if the shingles appear intact, water can still find its way in through nail holes, flashing gaps, or worn-out seams in the underlayment.

Brad’s Construction inspects the entire roofing system to identify whether your shingles, flashing, or underlayment are responsible for the leak.

2. Curling, cracking, or blistered shingles

Shingles showing signs of curling or cracking may be more than just cosmetic damage.

• • • Trapped heat or moisture beneath the surface often causes shingles to deform.
    • This usually signals deteriorating or improperly installed underlayment that no longer allows the roof to breathe.

Left unaddressed, these issues can shorten the life of your shingles and increase the risk of moisture intrusion.

3. Mold or mildew in the attic

When underlayment fails, moisture can rise into the attic space, especially in homes without proper ventilation.

• • • Look for musty odors, dark patches on rafters, or visible mold on insulation.
    • These symptoms may not be apparent from the roof surface, but they often indicate that your underlayment is no longer preventing moisture transfer from outside.

Mold and mildew can also reduce indoor air quality, making this more than just a roofing concern, it becomes a health concern, too.

4. Sagging or soft roof decking

Your roof deck (typically plywood or OSB) should feel solid underfoot and appear straight from the ground.

• • • If your roof feels spongy when walked on or appears wavy or sagging, it’s a strong indicator that moisture is infiltrating beneath the shingles and soaking into the decking.
    • Often, this happens when the underlayment fails to protect the decking from water saturation.

This can lead to costly structural damage if left unresolved, and it usually requires more than just shingle replacement.

5. Ice dams followed by interior water damage

In cold Wisconsin winters, ice dams are a common problem, but they shouldn’t lead to interior leaks.

• • • Ice that forms along roof edges can trap melting snow, forcing water to back up under shingles.
    • If your underlayment isn’t waterproof or has degraded, it won’t prevent that water from seeping into your attic or walls.

High-performance underlayment, like the materials used by Brad’s Construction, can help prevent damage from even the harshest winter conditions.

6. Your roof is 20 years old or more

Even if your roof looks fine from the ground, aging underlayment can become brittle, curled, or cracked over time, especially with older felt-based products.

• • • Most asphalt roofs have a lifespan of 20–25 years, and underlayment is often the first component to deteriorate.
    • If your roof is approaching this age, it's smart to schedule a professional evaluation before problems start.

When replacing a roof, Brad’s Construction installs modern synthetic underlayments that offer greater durability, better moisture resistance, and longer lifespans than outdated felt options.

Case example: Underlayment failure in Waupun

We recently worked with a homeowner in Waupun who noticed dark ceiling stains after a windstorm. While the shingles were still intact, our inspection revealed deteriorated felt underlayment that had absorbed years of moisture. We replaced the old roofing system with high-performance synthetic underlayment and architectural shingles, restoring their home's protection and peace of mind.

Why professional inspection matters

Not all roof issues are visible to the untrained eye. In fact, roof underlayment problems are often hidden beneath shingles, making them difficult to detect without removing materials or conducting a proper attic inspection. That’s why working with an experienced contractor like Brad’s Construction is so important.

Our team brings years of expertise in identifying signs of underlayment failure, even when your roof appears fine from the outside. We use hands-on techniques and modern tools—like moisture meters and thermal imaging—to examine your roofing system from the surface down to the structure.

When you schedule a professional inspection with Brad’s Construction, you can expect:

• • Thorough roof inspections that go beyond surface-level damage
  • Honest assessments and clear explanations of what we find and why it matters
  • Roof repairs to address localized issues without unnecessary replacement
  • Full roof replacements when damage is extensive or the roof is nearing the end of its life
  • Energy-efficient roofing upgrades that can improve performance and help lower utility bills
  • Detailed written estimates so you understand every cost before we begin

We don’t pressure you into a service you don’t need. At Brad’s Construction, our priority is helping you protect your home, maximize your investment, and make confident decisions about your roofing system.

Whether you're in Beaver Dam, Mayville, or anywhere else in Dodge County, we take pride in delivering trusted, high-quality roofing services with a reputation for honesty and craftsmanship.

Proudly serving Dodge County and surrounding areas

Brad’s Construction provides roofing and exterior remodeling services throughout Dodge, Fond du Lac, and Washington Counties, including:

• • Beaver Dam
  • Mayville
  • Waupun
  • Columbus
  • Horicon
  • Watertown
  • Fond du Lac
  • West Bend
  • Hartford
  • Campbellsport

We’re known for our craftsmanship, transparency, and commitment to helping homeowners get the most from their investment.

Don’t wait—get a roof inspection today

Protect your home with expert roofing from Brad’s Construction

If you’ve noticed signs of roof leaks, attic moisture, or shingle damage, don’t wait until costly structural damage occurs. Contact Brad’s Construction for a comprehensive roof inspection and honest evaluation of your underlayment and overall roof health.

We’re proud to serve homeowners across Dodge County and surrounding Wisconsin communities with reliable roofing services, siding replacement, gutter installation, and more.

Ready to schedule your estimate? Call today or request your inspection online.