When most Volusia County homeowners picture a new roof, they think about shingles — the color, the brand, the wind rating. But some of the most important protection on your roof is a layer you’ll never see once the job is done: the underlayment, and in particular the secondary water barrier underneath your shingles.
At Affordable Roofing & Construction, we’ve been re-roofing homes across Daytona Beach, Port Orange, New Smyrna Beach, Ormond Beach, DeLand and Deltona for over 20 years. If there’s one upgrade that’s easy to overlook but pays off in a Florida storm — and can even lower your insurance premium — it’s this one. Here’s what a secondary water barrier is, why Florida now requires it, and what it means for your home.
What Is Roof Underlayment?
Underlayment is the layer installed directly on top of your roof deck (the plywood or OSB sheathing) and underneath your shingles. It’s the last line of defense: if wind ever lifts or tears off shingles, the underlayment is what keeps rain out of your attic and living space.
There are three common types you’ll hear about in Florida:
- Felt (asphalt-saturated paper) — the old-school #15 or #30 “tar paper.” Cheap, but it can tear, wrinkle in the heat, and degrade over time.
- Synthetic underlayment — a woven polymer sheet. Lighter, stronger, more tear-resistant and more heat-stable than felt. A big step up.
- Self-adhered (peel-and-stick) underlayment — a rubberized-asphalt membrane that sticks directly to the deck and seals around every nail. This is what creates a true secondary water barrier.
What Makes It a “Secondary Water Barrier”?
A secondary water barrier (SWB) is a specific upgrade recognized by Florida’s insurance and building rules. It means the roof deck itself has been sealed against water intrusion — either with a fully self-adhered peel-and-stick membrane over the entire deck, or by taping the plywood seams with an approved flashing tape before the underlayment goes down.
The idea is simple but powerful. In a hurricane, the most common way water gets into a home isn’t a hole in the roof — it’s wind peeling shingles off and driving rain through the seams and nail holes in the deck. A secondary water barrier keeps that water out even if the shingles are gone. It’s the difference between a roof repair and a flooded, gutted interior.
Florida Now Requires More Than the Old “Tar Paper”
Florida’s Building Code has steadily tightened underlayment and deck-sealing requirements after every major hurricane season. Today, re-roofs in our high-wind region are held to a much higher standard than the single layer of felt that was common on older homes.
Depending on your roof and the current code, that can mean an enhanced underlayment system, sealed deck seams, and proper attachment designed for our wind zone. The practical takeaway for homeowners: if your roof was installed many years ago, it almost certainly does not have the deck sealing that today’s code and today’s insurers expect. A modern re-roof is your chance to fix that.
The Insurance Angle: How This Can Lower Your Premium
Here’s where it gets interesting for your wallet. In Florida, insurers offer wind mitigation credits — discounts for roof features that make your home more resistant to hurricane damage. A qualified secondary water barrier is one of the specific items rated on a wind mitigation inspection (the OIR-B1-1802 form your inspector fills out).
Combined with other mitigation features — like a proper nailing pattern, a sealed roof deck, and a hip roof shape — these credits can add up to meaningful savings on your homeowners premium, year after year. On many Volusia County homes, wind mitigation credits are one of the biggest reasons a new roof partially pays for itself over time.
This is a core part of how we work: we include wind mitigation with every roof we install, so you have the documentation you need to claim every credit you qualify for. If a secondary water barrier is right for your roof, we’ll make sure it’s installed to standard and shows up on your inspection.
Do You Need Peel-and-Stick Over the Whole Roof?
Not always — and honest guidance matters here. Full self-adhered coverage across the entire deck is the gold standard for water protection, but it costs more than synthetic underlayment. Whether it’s worth it depends on your roof slope, your budget, and how much insurance savings offset the cost.
- Low-slope and valley areas almost always benefit from self-adhered membrane — these are the spots most prone to water pooling and wind-driven leaks.
- Eaves and edges are common places to run peel-and-stick even when the field of the roof uses synthetic.
- A full peel-and-stick deck gives you the strongest secondary water barrier and the cleanest wind mitigation result — a smart choice for coastal homes in New Smyrna Beach, Daytona Beach and Ormond Beach.
During your free estimate, we’ll walk you through the options and give you a straight answer about what actually makes sense for your roof — not just the most expensive package.
What to Ask Your Roofer
Because the underlayment is hidden once the shingles go on, it’s an easy place for a low-bid contractor to cut corners. Before you sign, ask:
- What type of underlayment are you installing — felt, synthetic, or self-adhered?
- Will my roof have a secondary water barrier, and will it be documented for wind mitigation?
- Are the roof deck seams being sealed to current Florida code?
- Will I get a wind mitigation inspection so I can claim insurance credits?
If a contractor can’t answer those clearly, that tells you something. A quality Florida re-roof is a system — deck, underlayment, water barrier, flashing, and shingles all working together — not just a bundle of shingles nailed down.
Get a Free Estimate in Volusia County
A secondary water barrier is one of those upgrades you don’t think about — until the one storm where it saves your home. If you’re planning a re-roof anywhere in Volusia County or Central Florida, we’ll show you exactly how your underlayment and water barrier will be built, and how much you could save on insurance.
Affordable Roofing & Construction is licensed and insured (CCC 1327602 & CGC 1509441), CertainTeed ShingleMaster credentialed, and has served Central Florida for over 20 years. Every roof includes wind mitigation and a 5-year labor warranty.
Call us today at 386-392-8952 for a free, no-obligation estimate.
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