Self-adhered (peel-and-stick) underlayment is a waterproof, self-sealing membrane. Synthetic underlayment is a tough polymer sheet that sheds water but is nailed down. For most sloped asphalt-shingle roofs, synthetic is the everyday choice and self-adhered goes in the places water is most likely to get in. In South Florida, where storms push rain sideways, many homeowners also want self-adhered over more of the deck. But underlayment only gets chosen when the old roof comes off. If your shingles are aging but still maintainable, you may be able to put that decision, and the bill that goes with it, years down the road. Call us before you call the roofer, and we'll inspect the roof and tell you whether it qualifies for renewal.
TL;DR
- Self-adhered membrane bonds to the deck and seals around nails. Synthetic is a woven polymer sheet fastened with cap nails or staples. It is water-resistant, not fully waterproof.
- Typical installed cost is roughly $0.35 to $0.65 per square foot for synthetic and $1.00 to $2.50 for self-adhered, depending on the source. Full-deck self-adhered costs the most.
- Florida requires a secondary water barrier when you reroof, and self-adhering products are one of the ways to meet it. Your roofer and permit office confirm what applies to your address.
- Underlayment is chosen at tear-off. If your shingles still qualify for preservation, you may not need a tear-off yet.
Table of Contents
- What underlayment does and where it sits
- Self-adhered vs. synthetic: how they compare
- What about ice and water shield?
- What Florida requires
- What it costs
- How long does self-adhered underlayment last?
- Which should you choose?
- The question to ask first: do you need a new roof yet?
- What we do about it
- Our perspective
- FAQ
- Sources
What underlayment does and where it sits
Underlayment is the layer between the plywood deck and your shingles. Shingles are the first line of defense. Underlayment is the backup that catches water if wind lifts a shingle, a nail hole leaks or a shingle goes missing in a storm.
The two products you are comparing work differently:
- Synthetic underlayment is a woven or spun polypropylene or polyethylene sheet that is mechanically fastened with cap nails or staples. The asphalt roofing industry's technical bulletin describes it this way.
- Self-adhered underlayment (also sold as peel-and-stick, or under the ice and water shield name) is a rubberized asphalt or butyl membrane with an adhesive backing. The installer peels off a release liner and presses it onto a clean, dry deck, per the same bulletin.
The butyl-based versions are the premium tier. Fine Homebuilding reports that butyl adhesive costs 50% to 90% more than asphalt-based membranes. It has a higher use temperature, 300°F against 240°F for most asphalt-based ones, and is better suited to hot, sunny locations.
Self-adhered vs. synthetic: how they compare
| Factor | Synthetic | Self-adhered (peel-and-stick) |
|---|---|---|
| Material | Woven or spun polypropylene or polyethylene | Rubberized asphalt or butyl with adhesive backing |
| Attachment | Cap nails or staples | Adhesive bond to the deck |
| Waterproof? | Water-resistant, not fully waterproof | Waterproof |
| Around nail holes | Can leak if fasteners are uncapped or water stands | Seals around fasteners |
| Weight and handling | Light, large rolls, fewer seams | Heavier, sticky, needs clean dry deck |
| Typical use | Most of the roof | Eaves, valleys, low slopes, or full deck for extra protection |
| Cost | Lower | Higher |
The differences come down to three things.
Water protection
Roofing Elements magazine states that self-adhesive underlayment provides a waterproof barrier, while synthetic is water-resistant but not entirely waterproof. Fine Homebuilding adds that peel-and-stick seals around nail shanks, so water is much less likely to leak through than with ordinary underlayment.
That matters in Broward and Palm Beach counties. Summer thunderstorms and tropical systems drive rain sideways, and water that gets under a lifted shingle meets the underlayment next.
Fastening
Synthetic needs capped nails or staples to hold securely. A manufacturer's technical paper notes that fastener holes can stretch or leak if uncapped fasteners are used. Self-adhered membranes avoid this because the adhesive plugs the hole.
Heat and sun exposure
Both products spend their service life under shingles, not in open sun. Still, installers work on hot decks. Self-adhered needs a clean, dry deck to bond. Synthetic rolls cover large areas quickly, which means fewer seams and less time on the roof.
What about ice and water shield?
Ice and water shield is the common name for a self-adhered membrane. It was developed for cold climates, where melting snow backs up behind ice dams and pushes water under shingles. You won't see ice dams in Boca Raton or Fort Lauderdale. The same property, a waterproof membrane that self-seals, is what makes it useful here against wind-driven rain. Fine Homebuilding notes peel-and-stick is attractive wherever water can get under shingles, from ice dams or wind-driven rain.
So the question here is not ice. It is how much of your deck you want sealed.
What Florida requires
Florida's building code calls for a secondary water barrier, a layer that protects the structure if the primary roof covering is damaged or removed by hurricane-force winds. The state's secondary water barrier guidance lists methods for reroofing site-built single-family homes. One is covering all sheathing joints with a strip of self-adhering polymer-modified bitumen tape at least 4 inches wide, then installing an approved underlayment over the deck and tape. Another approach is a self-adhering membrane over the deck.
In the High Velocity Hurricane Zone (Miami-Dade and Broward), the Florida Building Code 8th Edition mandates secondary water barriers beneath steep-slope roof coverings. Palm Beach County and individual cities can have their own permit details, so the permit your roofer pulls is the final word on what your roof needs.
The practical point: at your next replacement, you will almost certainly end up with some self-adhering product on the deck, whether as seam tape, as a full membrane or in vulnerable areas, topped by synthetic or another approved layer.
What it costs
Prices vary widely by source, roof and region. Here is what recent published guides report per square foot, installed:
| Source (2026) | Synthetic | Self-adhered |
|---|---|---|
| Rise Roofing | $0.35 to $0.65 | $1.00 to $2.50 |
| Maryland Siding Pros | $0.70 to $1.80 | $1.10 to $2.50 |
| Parrottsville Roofing | $0.60 to $1.20 | $1.50 to $3.00 |
A typical 2,000 sq ft roof needs roughly 2,200 sq ft of underlayment, because of overlaps and waste. Using the first row above as an example, that is about $770 to $1,430 for synthetic and $2,200 to $5,500 for full-deck self-adhered. That is our arithmetic on a published range, not a quote for your home.
Three things move the number:
- Coverage. The price spread is driven largely by how much peel-and-stick goes on: only eaves and valleys, or the full deck.
- Complexity. Steep pitches, multiple angles and complicated eaves raise labor.
- Adhesive type. Butyl costs more than asphalt-based membranes, as noted above.
In all cases, underlayment is a line in a bigger bill. A full replacement on a South Florida home typically runs $15,000 to $30,000 by our owner's estimate, and underlayment is one part of that.
How long does self-adhered underlayment last?
There is no single number. One roofing company reports that peel-and-stick under shingles typically lasts 10 to 30 years, depending on exposure and product grade. Another points out that because it sits beneath the roof covering, its useful life depends on the whole assembly: the product, installation, drainage, weather and warranty terms.
That last point is the key one. Underlayment is protected by your shingles. When the shingles dry out, crack and lose granules, the backup layer starts working harder than it was meant to.
Which should you choose?
For most homeowners, the decision is simple:
- Synthetic across the field of the roof is the modern default on most shingle work, according to one field guide.
- Self-adhered at the weak points: eaves, valleys, penetrations and low-slope sections.
- Full-deck self-adhered if you live on the coast, in a high-wind area or want a stronger secondary barrier. Some homeowners and insurers opt for it as protection against wind-driven rain. Full coverage is premium and costs more.
Whatever you pick, get the exact product named in the written proposal. A broad category tells you less than a specific product and installation method.
The question to ask first: do you need a new roof yet?
Everything above applies when shingles come off. Many South Florida roofs get replaced because they look tired, not because they have failed. Sun and heat dry out asphalt, shingles turn brittle, and granules wash off. That is a maintenance problem before it is a replacement problem.
If your shingles are aging but intact, preservation can restore flexibility and slow the deterioration. A roof that qualifies can stay in service rather than going to the landfill, and the underlayment decision waits. Our guides on checking shingle adhesion and affordable weatherproofing for South Florida show what to look for. If wind resistance is your concern, see how wind-rated shingles qualify in Florida.
If the roof is leaking at the deck, soaked through or structurally failing, replacement is the right call, and the comparison above is your guide.
What we do about it
We are not roofers or roof cleaners. We inspect the roof, assess its condition and tell you whether it qualifies for preservation and renewal. The inspection is free.
If your roof qualifies, our certified Fresh Roof Green Soy Technology is designed to restore flexibility, lock in granules and extend the life of qualifying asphalt shingle roofs, and you could save up to 80% compared with a full replacement. The work comes with a 6-year transferable warranty. We serve homes in Broward and Palm Beach counties.
Schedule your free roof assessment and find out whether your roof qualifies before you spend on a tear-off. You can read how our process differs from standard rejuvenation oils or see our services.
Our perspective
Homeowners ask us about underlayment because they are about to replace a roof and someone handed them a quote with three options on it. It is a good question. Self-adhered membrane is the better water barrier. Synthetic is the practical workhorse. In our climate, a good installer uses both where they make sense.
What we want you to ask first is a different question: does this roof need to come off at all? Florida sun and heat dry out shingles over time. The result is brittle, curling shingles that shed granules. That happens long before the deck or the underlayment has failed. Too often, a roof gets replaced at $15,000 to $30,000 when it could have been maintained.
Our approach is built on that gap. We inspect, we assess honestly and we tell you if the roof qualifies for renewal. Our certified Green Soy Technology is designed to restore flexibility and hold granules in place, and we back qualifying jobs with a 6-year transferable warranty. If you preserve the roof you have, you keep the shingles and the underlayment working together for longer. You also keep thousands of pounds of old shingles out of the landfill.
Call us before you call the roofer.
Daniellison
FAQ
Is self-adhered underlayment better than synthetic?
For water protection, yes. It is waterproof and seals around nails, while synthetic is water-resistant. Synthetic costs less and is the usual choice for most of a shingle roof. Many installs combine them, with self-adhered at eaves, valleys and other vulnerable spots.
Is peel and stick the same as ice and water shield?
In practice, yes. Both names describe a self-adhering rubberized membrane. Ice and water shield began as a cold-climate product against ice dams. In South Florida it earns its place against wind-driven rain.
Does a roof need underlayment?
Yes. Underlayment is the backup layer under the shingles. Florida's building code also calls for a secondary water barrier when you reroof, so your roofer should specify one in the proposal and the permit.
Can I choose underlayment without replacing the roof?
No. Underlayment sits under the shingles, so it is installed during a tear-off or new roof. If your roof is still maintainable, a free assessment from us can tell you whether it qualifies for preservation, which may let you delay a tear-off.
Sources
- ARMA technical bulletin on asphalt shingle underlayment
- Fine Homebuilding: adhesive layers of peel-and-stick membranes
- Roofing Elements: Underlayment 101
- Fine Homebuilding: basics of peel-and-stick underlayment
- Tarco: Rethinking Roofing Underlayments
- Florida Building Commission: secondary water barrier
- Florida Building Commission: underlayment performance in extreme wind
- Rise Roofing: underlayment types compared
- Maryland Siding Pros: underlayment costs
- Parrottsville Roofing: underlayment cost factors
- HomeMatchup: underlayment cost
- New England Metal Roof: peel-and-stick lifespan
- Carrollton Roof Contractor: peel-and-stick lifespan factors
- Anvil Field: roofing underlayment types