Uniform Mitigation Verification Inspection Form OIR-B1-1802 (Rev. 04/26) Adopted by Rule 69O-170.0155, F.A.C. Page 3 – Section 8 — Sealed Roof Deck / Secondary Water Resistance (SWR)
Section 8 — Sealed Roof Deck / Secondary Water Resistance (SWR)
Section 8 addresses something that may not be as dramatic as losing your roof in a hurricane, but is often just as costly to deal with afterward — water intrusion. When a major storm damages or strips away your roof covering, everything beneath it is suddenly exposed to rain. Without a secondary layer of protection under that covering, water can pour directly into your home through the roof decking. Section 8 documents whether your roof has such a layer.
The form defines this feature as a Secondary Water Resistance layer, commonly referred to as SWR or a sealed roof deck (often also called a secondary water barrier). The section opens with an important clarification that sets the tone: standard underlayment and hot-mopped felts do not qualify. The standard felt paper that goes under shingles or tile on most roofs is not a sealed roof deck for the purposes of this form. The materials that qualify are specifically engineered to create a true secondary barrier against water penetration — not just a drainage layer.
Answer A — Sealed Roof Deck / SWR Present
To qualify as Answer A, one of the following must be present:
- Sub-item 1 — Fully Adhered Polymer-Modified Bitumen Underlayment A fully adhered modified bitumen membrane installed directly over the roof decking, complying with ASTM D1970. This is a self-adhering peel-and-stick product that bonds directly to the deck surface, sealing it against water intrusion. It is one of the most reliable SWR methods available and is commonly seen on homes where the roof was replaced under the 2007 or later Florida Building Code, which began requiring SWR more broadly.
- Sub-item 2 — Tape Over Roof Deck Seams A minimum 3.75-inch-wide strip of self-adhering modified bitumen tape, complying with ASTM D1970, applied over every seam where two pieces of roof decking meet. An alternative qualifying product is self-adhering flexible flashing tape complying with AAMA 711 Level 3. The idea here is that the seams between sheets of plywood or OSB are the most vulnerable points for water to enter — taping those seams creates a sealed barrier even when the rest of the deck is covered with standard underlayment.
- Sub-item 3 — Double Layer of Felt or Synthetic Underlayment Two complete layers of qualifying underlayment — ASTM D226 Type II, ASTM D4869 Type III or IV, or ASTM D8257 — installed without tape at the seams. The double layer provides redundancy that a single layer of standard felt does not. Note that both layers must meet the specified ASTM standards — not every underlayment product qualifies.
- Sub-item 4 — Spray Foam* Spray polyurethane foam installed along all rafter and deck intersections and at all panel joints. This is the same spray foam referenced in Section 5 for deck attachment — when properly installed, it simultaneously strengthens the deck attachment and seals the deck against water intrusion. The form includes an additional checkbox here (marked ★) that the inspector checks if the spray foam covers the entire underside of the roof deck rather than just the seams and joints. Full coverage is a more robust application than perimeter-only foam. (IMPORTANT NOTE: DOES NOT INCLUDE SPRAY FOAM INSULATION, see notes further below*)
Answer B — No Sealed Roof Deck No qualifying SWR layer is present. Standard underlayment was used and the roof deck is not otherwise sealed. This is the most common answer for homes in Southwest Florida, particularly older homes and those re-roofed before SWR requirements became standard practice. Answer B means no credit is applied for this section, but it does not affect any other section of the form.
Answer C — Unknown or Undetermined The inspector was unable to confirm whether a qualifying SWR layer is present. This may occur when the roof covering is tile or metal and the underlayment beneath it cannot be directly observed, when attic access is limited, or when documentation of the underlayment type is not available. In these situations the inspector records what could and could not be verified and selects Answer C.
What This Means for SWFL Homeowners
If your roof was replaced in the last 10 to 15 years, there is a reasonable chance it has some form of qualifying SWR — particularly if the work was done under a permit and inspected. Fully adhered modified bitumen underlayments have become increasingly common as roofing contractors have become more familiar with Florida’s requirements. Peel-and-stick products like GAF WeatherWatch, CertainTeed WinterGuard, and similar products are widely used in this market.
If you are planning a roof replacement, asking your contractor specifically about SWR and requesting a product that meets ASTM D1970 is one of the more straightforward ways to improve your wind mitigation report outcome before the inspector ever arrives.
*Important: Standard Spray Foam Insulation Does Not Qualify
This is one of the most commonly misunderstood points in this section. If you have spray foam insulation in your attic — the kind sprayed across the underside of the roof deck as a thick continuous blanket for energy efficiency — that does not qualify as Answer E. The spray foam that qualifies is a completely different product used in a completely different way. It is a purpose-engineered closed-cell polyurethane foam adhesive applied precisely along the junction where each rafter or truss meets the roof deck and at every seam between deck panels. It must carry a Florida product approval number confirming it has been independently tested to achieve a specific wind uplift resistance rating. Standard spray foam insulation has not been tested for structural wind uplift and carries no such rating regardless of how thick or complete the application is.
To make things more complicated, a full spray foam insulation application can actually prevent the inspector from evaluating deck attachment at all — the nails and fasteners beneath the foam are completely obscured — which can result in an Unknown answer rather than any credit. If a contractor has suggested your spray foam will help your wind mitigation report, ask them for the specific product name, the Florida product approval number, and documentation confirming it was applied for structural wind uplift purposes. Without that documentation, it will not qualify.
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