Quick Answer
If shingles are the part of your roof everybody sees, underlayment is one of the parts doing quiet work underneath. It is not flashy. It does not make your house look bet
If shingles are the part of your roof everybody sees, underlayment is one of the parts doing quiet work underneath. It is not flashy. It does not make your house look better from the street. But when Utah weather starts doing Utah weather things - snow, wind, freeze-thaw, summer heat, and sudden storms - the layers under your shingles matter a lot.
So yes, you need underlayment. And more importantly, you need the right underlayment installed in the right places as part of a complete roof system.
At IWC Roofing, we do not look at underlayment as a throwaway line item. A roof replacement should include proper underlayment, upgraded ice and water protection, and the accessories needed to help the whole system perform the way it is supposed to.
TLDR: Do You Need Roof Underlayment?
Yes. Roof underlayment is a protective layer installed between the roof decking and the shingles. It helps protect the roof deck from water intrusion if wind, ice, snow, or a damaged shingle lets moisture get past the outer roofing layer.
For Utah homeowners, underlayment matters because roofs deal with snow, ice damming, wind-driven rain, UV exposure, and big temperature swings. The basic roof quote should explain what underlayment is included, where ice and water barrier is installed, and whether the roofing products are part of a matched system.
IWC Roofing typically installs Owens Corning Duration shingles with Owens Corning accessories, upgraded ice and water barrier, and 6 feet of ice and water protection at the eaves instead of the standard 3 feet. IWC also includes ridge ventilation, uses all in-house Utah crews, and offers a 20-year workmanship warranty.
What Is Roof Underlayment?
Roof underlayment is the layer installed directly over the roof decking before the shingles go on. Think of it like a backup jacket underneath your outer coat. The shingles take the first hit from the weather, but the underlayment helps protect the wood deck if water gets past the shingles.
Underlayment is not meant to be your main waterproofing forever. Shingles are still the primary roof covering. But underlayment gives the roof system another line of defense, especially during installation, storms, wind events, ice damming, or shingle damage.
A roof quote that only talks about shingles is missing part of the story. A roof is a system, and underlayment is one of the important hidden pieces.
The Main Types of Roof Underlayment
1. Felt Underlayment
Traditional felt underlayment has been used for a long time. It is usually made with asphalt-saturated material and often comes in 15-pound or 30-pound versions. Felt can work, but it is not always the best option compared to modern synthetic products, especially when you are building a higher-quality roof system.
2. Synthetic Underlayment
Synthetic underlayment is a newer, commonly used option that is generally lighter, more tear-resistant, and easier for crews to work with than traditional felt. It can also perform better during installation because it tends to lay flatter and hold up better while the roof is being installed.
On a Utah roof, synthetic underlayment is often a better fit for homeowners who want a cleaner, stronger roof system instead of the bare-minimum approach.
3. Ice and Water Barrier
Ice and water barrier is not the same thing as basic underlayment. It is a self-adhered membrane used in the most vulnerable parts of the roof. It is commonly installed at eaves, valleys, roof-to-wall areas, and other leak-prone areas.
This is a big deal in Utah because ice damming is one of the most common problems we see. When snow melts and refreezes near the eaves, water can back up under the shingles. Ice and water barrier helps add protection where that kind of problem is most likely to happen.
Where Should Underlayment and Ice and Water Barrier Be Installed?
A good roofer should be able to tell you exactly what is being installed and where. Do not settle for a vague line that says “underlayment included” without details.
Important areas include:
• The main roof deck - covered with underlayment before shingles are installed.
• Eaves - especially important in Utah because of snow, ice, and freeze-thaw cycles.
• Valleys - where two roof planes meet and water naturally concentrates.
• Roof-to-wall transitions - where roofing meets siding, stucco, brick, or vertical walls.
• Around penetrations - pipe boots, vents, chimneys, and other areas where leaks commonly start.
• Low-slope or trouble areas - sections that move water more slowly or have a history of leaks.
IWC typically installs 6 feet of ice and water protection at the eaves instead of the standard 3 feet because Utah roofs need more than the bare minimum in many situations.
Why Underlayment Matters So Much in Utah
Utah roofs take a beating. Homeowners along the Wasatch Front, including Salt Lake County, Utah County, Davis County, Weber County, Park City, Tooele, and nearby areas, deal with a mix of weather that can be hard on a roof.
The big Utah roof problems we see most often are:
• Ice damming
• Under-ventilation
• Unaddressed wear and tear
Underlayment helps with water protection, but it works best when the whole system is done right. If the roof is poorly ventilated, hot attic air can contribute to uneven snow melt and ice dam issues. If valleys or flashing details are rushed, underlayment may not save the roof from a bad installation. If a roof is simply worn out, hidden layers can only do so much.
That is why IWC looks at the roof as a complete system: shingles, underlayment, ice and water barrier, ventilation, accessories, flashing details, and workmanship.
Does Underlayment Affect Your Roof Warranty?
It can. Manufacturer warranties often depend on the roofing system being installed according to manufacturer instructions and with qualifying components. Owens Corning’s roofing warranty resources explain that extended warranty options are tied to roofing system products and contractor qualification, not just the shingle sitting on top.
That is one reason IWC most often installs Owens Corning Duration shingles with Owens Corning accessories. Mixing random materials from different brands may save a little money upfront, but it can create warranty headaches later.
A homeowner should not have to become a roofing manufacturer expert just to understand their warranty. Your roofer should be able to explain which products are being used and how they affect the roof system warranty.
What Should a Roof Quote Say About Underlayment?
A detailed roof quote should tell you more than “new roof installed.” When it comes to underlayment, ask for clear answers on:
• What type of underlayment is included
• Whether it is synthetic or felt
• What brand or product line is being installed
• Where ice and water barrier is included
• How much ice and water protection is being installed at the eaves
• Whether valleys are protected
• Whether roof-to-wall areas are addressed
• Whether the accessories match the shingle system
• How the underlayment affects warranty coverage
If one roofer is much cheaper than the others, this is one of the first places to look. They may be using a cheaper underlayment, less ice and water barrier, or vague material specs that leave room for shortcuts.
Red Flags Around Underlayment
Watch out for these red flags:
• The quote does not say what underlayment is being installed
• The roofer says underlayment does not matter
• Ice and water barrier is not mentioned at all
• The quote only includes the bare minimum with no explanation
• The roofer cannot explain where ice and water barrier will be installed
• They mix cheap accessories with upgraded shingles but still talk like you are getting a premium roof system
• They make warranty promises without showing which products qualify
A good roofer should not make you feel annoying for asking about the hidden parts of the roof. That is where a lot of the long-term value lives.
What IWC Includes in a Better Roof System
IWC’s standard roof replacement is built around giving homeowners better long-term value, not just the lowest price on paper.
A typical IWC roof replacement includes:
• Owens Corning Duration shingles
• Owens Corning accessories to help maintain warranty coverage
• Upgraded ice and water barrier
• 6 feet of ice and water protection at the eaves instead of the standard 3 feet
• Ridge ventilation
• All in-house Utah crews
• Most customers qualifying for a 50-year non-prorated manufacturer warranty, transferable once
• IWC’s 20-year workmanship warranty
That is the kind of detail homeowners should be comparing when they look at roofing quotes. Not just “how much is the roof?” but “what roof system am I actually getting?”
Real Utah Example: Why Hidden Details Matter
The Sandy storm leak project is a good example of why roof system details matter. That homeowner had been dealing with serious leaking through the last few storms. IWC was able to replace the roof within two days before the next storm hit, stopping the leaks and helping prevent more interior damage.
When a roof is already leaking, the visible shingle layer is only part of the problem. The eaves, valleys, underlayment, flashing, and ventilation all need to be looked at. A quick patch may help in some situations, but when the system is failing, the hidden layers have to be addressed correctly.
Frequently Asked Questions
- Do I really need roof underlayment?
- Yes. Underlayment is an important protective layer between the roof decking and shingles. It helps protect the roof deck if water gets past the shingles because of wind, ice, storm damage, or installation details.
- Is synthetic underlayment better than felt?
- Synthetic underlayment is often stronger, lighter, and more tear-resistant than traditional felt. Many modern roof systems use synthetic underlayment because it performs well during installation and provides a cleaner roof system.
- Is ice and water barrier the same as underlayment?
- No. Ice and water barrier is a self-adhered membrane used in more vulnerable areas like eaves, valleys, and roof-to-wall transitions. It is more protective than standard underlayment in leak-prone areas.
- Where should ice and water barrier go on a Utah roof?
- Common areas include eaves, valleys, roof-to-wall transitions, and leak-prone areas around penetrations. IWC typically installs 6 feet at the eaves instead of the standard 3 feet.
- Can a roof fail if the shingles are good but the underlayment is bad?
- Yes. A roof is a system. Good shingles help, but poor underlayment, bad ventilation, weak flashing, or sloppy installation can still lead to leaks and early roof problems.
- Should underlayment be listed in my roof quote?
- Yes. A detailed roof quote should explain the type of underlayment, where ice and water barrier is installed, what accessories are included, and how the products affect warranty coverage.
- Does underlayment help with ice dams?
- Ice and water barrier can help protect vulnerable areas from water intrusion caused by ice dams. However, ventilation, insulation, and proper roof design also matter when trying to reduce ice dam risk.
- What areas does IWC Roofing serve?
- IWC serves much of the upper half of Utah, with Salt Lake County, Utah County, Davis County, and Weber County being the most common service areas. IWC also serves areas like Park City, Tooele, and surrounding Wasatch Front communities.