Question 3 of the Uniform Mitigation Verification Inspection Form (OIR-B1-1802), commonly referred to as the Wind Mitigation Form, assesses the roof deck attachment, which serves as a critical structural element in preventing roof failure during high winds. This question evaluates how the roof sheathing (like plywood or OSB) is fastened to the trusses or rafters, directly impacting your eligibility for insurance credits. In this deep dive, we’ll explore the history of roof deck attachment standards, what the question asks, how inspectors assess it, the science behind its importance, common scenarios, and what it means for you as a homeowner.
The History of Roof Deck Attachment Standards in Florida: Lessons from the Storms
Florida’s roof deck attachment requirements were shaped by the devastating lessons of Hurricane Andrew in 1992, a Category 5 storm that exposed the vulnerabilities of inadequate fastening systems. Many roofs failed as sheathing panels were uplifted and blown off, leading to structural collapse and water intrusion that compounded damages, contributing to over $25 billion in losses. This catastrophe prompted a major overhaul of building standards, particularly in Miami-Dade and Broward Counties, designated as the High-Velocity Hurricane Zone (HVHZ). The South Florida Building Code (SFBC-94), effective September 1, 1994, introduced rigorous requirements for roof deck attachments, mandating stronger fasteners and closer spacing to withstand high wind uplift forces.
By March 1, 2002, the Florida Building Code (FBC 2001) was implemented statewide, requiring 8d common nails at 6 inches on center along edges and 12 inches in the field for plywood decks. From October 1, 2007, FBC 2007 mandated 8d ring-shank nails for roof replacements on pre-2002 homes, driven by IHRC research post-Hurricane Charley (2004), with wind zones ≤110 mph needing added ring-shank nails and ≥120 mph requiring full re-nailing. Refinements in FBC 2020, informed by Hurricanes Irma (2017) and Michael (2018), eliminated weaker attachments in high-wind areas, building on lessons from Hurricane Andrew (1992) and SFBC-94 (1994). The 2024 ARA and IHRC studies validate these standards, showing up to 38% loss reductions, with ring-shank nails (140 psi uplift) outperforming 2″ staples (79 psi).
What is Question 3? Breaking Down the Question Itself
“Roof Deck Attachment: What is the weakest form of roof deck attachment?”
Question 3 on the Wind Mitigation Form evaluates the strength of the attachment between the roof sheathing (typically plywood, OSB or lumber decking) and the supporting trusses or rafters. It categorizes the attachment into levels based on fastener type, size, spacing, and equivalent uplift resistance, identifying the “weakest” level present. Attachment Levels
A. Basic Attachment This category represents the minimum standard, such as using staples or 6d nails spaced 6 inches apart on the edges and 12 inches in the “field” (the central area of the sheathing panel). This connection has a mean uplift resistance of approximately 55 psf.
B. Improved Attachment This level is met by having a connection system that provides a mean uplift resistance of at least 103 psf. While commonly achieved with 8d nails spaced a maximum of 12 inches in the field, this category explicitly includes any system of screws, nails, adhesives, or other documented fastening methods that is proven to have an equivalent or greater wind resistance.
C. Strongest Attachment This represents the most secure attachment, requiring a mean uplift resistance of at least 182 psf. While commonly achieved with 8d nails spaced a maximum of 6 inches in the field, this category explicitly includes any system of screws, nails, adhesives, or other documented fastening methods that is proven to have an equivalent or greater wind resistance.
How to Answer Question 3: Evaluation and Documentation
We perform an inspection inside your attic to verify your roof deck fastening and ensure there is clear documentation for review. We confirm sheathing thickness and truss/rafter spacing, identifying fastener type and size with exposed nails or what we call “shiners” (2.5″ nails protruding less than 2″). With a tape measure, we assess spacing, allowing up to 3 missed or split nails per 48″. Our photos include close-ups of the nails and lengths, plus wider shots marking measurement between those nails, reflecting the weakest attachment area. Classifications are: Checkmark A (staples or 6d nails), Checkmark B (7/16″ OSB/plywood with 8d at 12″), Checkmark C (8d at 6″ or ring-shank equivalents), with reinforced concrete noted separately. If access is obstructed or size/spacing can’t be confirmed, we select “No Access” or “Unknown” with a clear explanation. The report features photos with captions linking to spacing and fastener details.
The Science Behind the Savings: ARA Studies and Loss Reductions
The insurance discounts tied to Question 3 are grounded in data from engineering studies, most recently the 2024 ARA Loss Mitigation Study commissioned by the Florida Office of Insurance Regulation. Using the HURLOSS model, this study simulates hurricane impacts across thousands of scenarios, analyzing how roof deck attachments perform under wind uplift and debris impacts. The findings show that stronger attachments (Levels B and C) reduce insured losses compared to Level A, particularly in high wind events, by preventing sheathing uplift and subsequent water damage.
These reductions translate into meaningful premium discounts for the wind portion of your policy, covering the dwelling, contents, and additional living expenses. The Florida Commission on Hurricane Loss Projection Methodology validates these models, ensuring their reliability. Compliant attachments not only save money but also enhance a home’s ability to withstand storms, protecting both property and occupants.
Common Field Scenarios and Nuances: What Affects Question 3
Roof configurations and access issues can complicate Question 3, but they don’t always change the answer:
- Attic Access Challenges: If inaccessible, it may be marked “Unknown,” potentially forfeiting credits; inspectors may use alternative views if possible.
- Mixed Attachments: Homes with varying levels (e.g., main roof Level C, addition Level A) are rated by the weakest section.
- Upgrades: Adding nails or ring shanks to existing decks can elevate from A to C; programs like My Safe Florida Home offer grants for this.
- Condition Issues: Question 3 doesn’t assess decay or corrosion, but severe issues may disqualify credits.
What It All Means for Homeowners: Savings, Safety, and Next Steps
Question 3 signals that your roof deck attachment meets wind resistance standards, unlocking insurance credits that can substantially reduce your annual premiums. Beyond savings, stronger attachments offer greater protection against hurricanes, reducing the risk of costly repairs and ensuring safer shelter for your family. Programs like My Safe Florida Home can provide grants to upgrade weaker attachments, amplifying these benefits.
Plain-Language Takeaway
If your roof deck uses strong fasteners like 8d nails at close spacing (Level C), you’re likely in line for savings from Question 3. This means lower insurance costs and a roof better equipped to handle Florida’s storms. Reach out to the professionals here at Orlando Inspex to confirm eligibility, and schedule an inspection to document it.
For more resources, visit the Citizens Insurance wind mitigation page or contact us to schedule your inspection!
