Florida Roof Deck Attachment Wind Mitigation Guide

Roof deck attachment is an important wind mitigation feature on the Florida OIR-B1-1802 inspection form. It describes how roof decking is secured to the trusses or rafters and helps determine which wind mitigation credits may apply under an insurance carrier’s approved rating plan.

How Roof Deck Attachment Is Graded on the Wind Mitigation Form

Section 5 of the April 2026 OIR-B1-1802 form asks inspectors to identify the weakest form of roof deck attachment. The form provides Options A through H, covering different fastening methods, uplift-resistance thresholds, reinforced concrete roof decks, spray foam systems, and situations where the attachment cannot be identified.

Inspectors evaluate the applicable roof decking and fastening characteristics, including sheathing thickness, nail size, nail spacing, truss or rafter spacing, and other approved attachment methods. Where the form permits an equivalent fastening system, documented uplift resistance may also be considered.

The resulting classification is used by insurance carriers to evaluate applicable roof deck attachment credits. The actual credit depends on the insurer’s approved rating methodology.

Roof Deck Attachment Options (Florida OIR-B1-1802)

• Option A – Basic Roof Deck Attachment:
  Plywood or oriented strand board (OSB) roof sheathing with a minimum thickness of 7/16″, attached to trusses or rafters spaced a maximum of 24″ on center, using staples or 6d nails spaced 6″ along the edges and 12″ in the field.
  OR batten decking supporting wood shakes or wood shingles, with maximum 24″ truss or rafter spacing.
  OR another fastening system with equivalent mean ultimate uplift resistance of at least 55 psf, but less than the requirements for Options B or C.
  Important form instruction: When the nailing or rafter spacing exceeds the specified limits, or the roof decking is thinner than specified, Option F – Other applies.
• Option B – 8d Common Nails at Maximum 12″ Field Spacing:
  Plywood or OSB roof sheathing with a minimum thickness of 7/16″, attached to trusses or rafters spaced a maximum of 24″ on center, using 8d common nails spaced a maximum of 12″ in the field.
  OR another fastening system shown to provide resistance equivalent to or greater than 8d common nails at the specified spacing, or a mean ultimate uplift resistance of at least 103 psf.
• Option C – 8d Common Nails at Maximum 6″ Field Spacing:
  Plywood or OSB roof sheathing with a minimum thickness of 7/16″, attached to trusses or rafters spaced a maximum of 24″ on center, using 8d common nails spaced a maximum of 6″ in the field.
  OR dimensional lumber or tongue-and-groove decking with at least 2 nails per board, or 1 nail per board when each board is 6″ wide or less.
  OR another fastening system shown to provide resistance equivalent to or greater than 8d common nails at the specified spacing, or a mean ultimate uplift resistance of at least 182 psf.
• Option D – Reinforced Concrete Roof Deck:
  A reinforced concrete roof deck as identified on the inspection form.
• Option E – Spray Foam Products:
  Spray foam products with an uplift resistance of 110 psf (FOS 1.5).
  The form specifies installation along rafter/deck intersections, all panel joints, and other applicable locations.
• Option F – Other:
  A roof deck attachment system that does not meet the preceding classifications. The inspector provides a description of the system.
• Option G – Unknown or Unidentified:
  The roof deck attachment cannot be adequately identified from the available inspection information.
• Option H – No Attic Access:
  The inspector cannot access the attic to evaluate the roof deck attachment.

Which Roof Deck Attachment Is Weakest?

Among the three conventional wood roof deck attachment classifications, Option A represents a lower documented uplift-resistance level than Options B and C.

Option A includes qualifying systems beginning at 55 psf, while Options B and C include higher specified resistance thresholds of 103 psf and 182 psf, respectively. These thresholds help distinguish the attachment classifications on the inspection form.

However, Options D and E describe different roof deck systems and should not simply be ranked according to the nail-spacing categories. Options F, G, and H identify other or insufficiently documented conditions rather than progressively stronger fastening systems.

The form asks for the weakest applicable attachment, so a stronger fastening pattern observed in one area does not necessarily establish the classification for the entire roof.

Carrier-specific note: Citizens currently maps Option E (qualifying spray foam) to its Level B roof deck attachment category and Options F, G, and H to Unknown or Unidentified for its systems. Other insurers may apply their own approved rating plans. These carrier mappings are not additional checkboxes on the inspection form.

Why Stronger Roof Deck Attachment Can Help Your Premium

Roof deck attachment helps resist wind uplift forces that can act on the roof during severe storms. Properly installed fastening systems with greater documented uplift resistance may qualify for more favorable wind mitigation treatment under an insurer’s rating plan.

For example, a roof deck attachment documented under Option C may qualify for a different credit than one documented under Option A. The actual premium difference depends on the insurance carrier, property characteristics, and other wind mitigation features.

During a roof replacement, a licensed roofing contractor may be able to evaluate whether improvements to the roof deck attachment are appropriate. If qualifying improvements are completed and properly documented, an updated wind mitigation inspection may support a different attachment classification.

The cost of an upgrade should be evaluated separately from any potential insurance savings. A stronger roof deck attachment can be beneficial for wind resistance, but a particular repair or improvement does not guarantee a specific premium reduction.

If you have a wind mitigation report and want to understand how the roof deck attachment classification affects your insurance options, I can review the form and compare available Florida homeowners insurance quotes using the documented features. The insurance carrier determines which credits apply under its approved rating plan.

Florida Roof Deck Attachment Wind Mitigation FAQs

What does roof deck attachment mean on a wind mitigation inspection?

Roof deck attachment describes how the roof decking is secured to the trusses or rafters. The Florida OIR-B1-1802 form evaluates fastening methods, sheathing characteristics, spacing, and applicable uplift-resistance criteria to classify the roof deck attachment.

How do inspectors determine the roof deck attachment rating?

Inspectors evaluate accessible roof deck attachment characteristics, including nail type, nail spacing, sheathing thickness, and truss or rafter spacing. The form requires the weakest applicable attachment classification. Other systems may require supporting documentation of equivalent uplift resistance.

Do 8d nails provide better wind mitigation credits than 6d nails?

Qualifying 8d common nail attachment patterns can meet the higher roof deck attachment classifications identified under Options B and C. However, nail size alone does not determine the classification. Sheathing thickness, nail spacing, framing spacing, and other applicable requirements must also be satisfied. The insurance credit depends on the carrier’s approved rating plan.

Does the spacing of nails affect wind mitigation discounts?

Yes. Nail spacing is one factor used to determine the roof deck attachment classification. Under the form’s conventional 8d common nail criteria, maximum field spacing of 12 inches is associated with Option B, while maximum field spacing of 6 inches is associated with Option C when the remaining requirements are met. The premium effect varies by insurer.

What documentation helps confirm roof deck attachment compliance?

Useful documentation may include inspection photographs, roofing contractor records, installation specifications, and supporting information about fastener type, spacing, sheathing thickness, or tested uplift resistance. The inspector must have sufficient evidence to support the reported classification, and the insurance carrier may request additional documentation.

Wind Mitigation Knowledge Center

Explore detailed guides for each wind mitigation feature:

• Florida Roof Covering & Product Approval Listing
• Roof Deck Attachment
• Roof-to-Wall Connection
• Roof Geometry
• Sealed Roof Deck / Secondary Water Resistance (SWR)
• Opening Protection
• Florida Wind Mitigation Inspection Hub

For personalized quotes with applicable wind mitigation credits evaluated, visit my Florida Home Insurance Quotes Page or complete the form below to request a homeowners insurance quote.

Disclaimer: This guide provides general information about roof deck attachment classifications on the Florida OIR-B1-1802 wind mitigation inspection form and their potential insurance implications. It does not replace a qualified inspection or professional roofing evaluation. Wind mitigation credits and premium calculations depend on the documented construction features and the insurance carrier’s approved rating plan.

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