When insuring a home in Florida, insurance agents may require a Wind Mitigation report to be provided. This report identifies the building features of the home that contribute to protection against hurricane force winds and preventing them from lifting the roof from the house. While this report may not determine if the home can be insured, it will contribute to the credits that impact insurance rates. The higher the level of hurricane protection, the more credits and potential discounts may be applied.
Roof Deck Attachment
The first category of the wind mitigation is the roof deck attachment, which addresses how the roof decking is attached to the roofing trusses. There are three common levels in this category, with C having the highest rating against hurricane uplift. The most common attachments in each category are as follows:
- A: 6d nails spaced 12 inches apart in the field and 6 inches apart along the edges.
- B: 8d nails spaced a maximum of 12 inches apart in the field.
- C: 8d nails spaced a maximum of 6 inches apart in the field.
Roof to Wall Attachment
The next category is the roof to wall attachment, which addresses how the roofing members are secured to walls of the home. This is achieved with nails or metal brackets which are embedded in the exterior walls and attach near the ends of the roofing members, near the soffits.
- Toe Nails: This refers to the roof being secured with either nails anchoring the trusses to the top plate of the wall, or a metal bracket attached to the top plate of the wall and attached to the rafter with 2 nails.
- Clip: A clip can use the same bracketing as a toe nail, however it is attached with 3 or more nails, which has been assessed through past evidence to hold more securely than just 2 nails.
- Single Wrap (Strap): This consists of a metal strap nailed twice to one side of the rafter, which then wraps over the top of the rafter to be nailed at least once more to either the top or opposite side of the rafter.
- Double Wrap: This can consist of a metal strap attached to the wall on both sides of the rafter, as well as nailed with at least three nails on each side of the rafter, or can consist of two single wraps side-by-side.
Roof Geometry
The roof geometry section identifies the wind deflection properties of the shape of the roof. These are categorized into being a Hip, Flat, and Other.
- A hip roof has downward slopes at all sides to deflect wind up and over the roof, with an allotment of up to 10% of the length allowed to be an other type.
- A flat roof is a roof on a building with 5 or more units, with at least 90% of the surface area being less than 2:12 slope.
- An Other roof is one that does not qualify as Hip or Flat. This is generally used to identify a gable roof.
Secondary Water Resistance
A Secondary Water Resistance barrier is an adhesive, Modified -Bitumen roofing layer that is applied to the roof sheathing. It is an additional waterproof layer to provide protection in the event of the loss of the roof covering. The wind mitigation simply asks for verification of if this layer is or is not present.
Opening Protection
The opening protection is an identification of the types of openings into the home as well as the impact ratings of the doors or windows in these openings. This category is an all-or-nothing credit. If any opening is not hurricane rated, the entirety of the structure is no longer considered to be impact rated. In order to consider an opening to be impact rated , the inspector will need to verify the rating, most likely through the rating sticker or label the manufacturer places on it.