I’m the owner-inspector behind By Builder Home Inspections. When I climb a roof in Tampa, Apollo Beach, or St. Petersburg, I look for one feature that separates storm-ready homes from the rest: a self-adhering membrane called Secondary Water Resistance.
SWR in One Sentence
A SWR is a peel-and-stick, polymer-modified bitumen sheet bonded directly to roof sheathing before shingles, tiles, or metal go on, creating a watertight seal over every nail hole and seam.
Why This Hidden Layer Pays Off in Florida
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Stops interior floods when wind tears off shingles during a hurricane.
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Adds points on the Florida Uniform Mitigation Verification Form (OIR-B1-1802), which means insurance discounts.
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Extends deck life by keeping plywood dry, cutting rot repairs.
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Raises resale value because buyers see lower risk on inspection reports.
The bar chart above compares average repair bills after a major Gulf-coast storm. Homes without SWR trend near $15 k in water damage, while those with SWR hover around $2.5 k. That one graphic tells the whole savings story.
What Counts as SWR ✅
| Qualifying Product | How Crews Install It |
|---|---|
| Peel-and-stick membrane (Grace Ice & Water Shield, Polyglass, GAF WeatherWatch) | Full-deck coverage, seams rolled tight |
| Closed-cell spray-foam deck seal | Applied from attic side, bonds each gap |
Anything that passes ASTM D1970 or TAS 114 meets the Florida standard. During an inspection I verify the brand stamp or pull up a shingle tab for proof.
What Doesn’t Count ❌
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Synthetic underlayment such as Tiger Paw unless self-adhered
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Standard 15- or 30-lb felt
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Hot-mop asphalt layers that lack peel-and-stick bonding
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Mechanically fastened tar paper
If your last roofer chose one of these, you won’t see the mitigation credit.
Field Checklist: How I Confirm SWR on Your Property
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Review re-roof permits to spot membrane brands ahead of time.
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Slide a flat bar under one shingle in a safe corner and photograph the membrane.
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Match product codes to manufacturer data sheets.
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Mark “A – Secondary Water Resistance” on the mitigation form.
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Email the signed PDF to you and your carrier the same afternoon.
I offer this service across the region:
Typical Upgrade Costs vs. Savings
| Scenario | Added Roof Cost | Insurance Payback |
|---|---|---|
| Full re-roof, peel-and-stick | $0.40 – $0.85 / sq ft | 2-4 years |
| Attic spray-foam seal | $2.00 – $2.75 / sq ft | 5-7 years |
Most clients recoup the expense long before the next major storm season rolls through.
Quick FAQ
Does partial valley coverage qualify?
No, the membrane must cover the entire deck.
Will spray foam overheat my shingles?
Deck temperatures rise a few degrees, well within manufacturer limits.
How long does peel-and-stick last?
Lab tests show adhesion past 30 years.
Still unsure? Ask anything when I’m on the ladder.
Ready to Verify Your SWR?
Send a request through my contact form and mention “SWR check.” I’ll confirm your membrane, document it for your insurer, and help you lock in the credit—saving money before the next storm cloud hits.
