IBHS FORTIFIED Roof

FORTIFIED is a voluntary building program run by the Insurance Institute for Business & Home Safety (IBHS), a US research organization funded by property insurers. FORTIFIED Roof is its first and most widely used level; FORTIFIED Silver and Gold add requirements for windows, doors, gable ends and the connection of the roof to the walls. The program is based on IBHS laboratory and field research into how homes fail in storms.

Unlike a product rating, FORTIFIED is a designation for a whole home. A trained evaluator inspects and documents the work during installation, and IBHS issues a certificate when the requirements are met.

Key requirements

The FORTIFIED Roof standard asks for several upgrades beyond typical code minimums:

• Sealed roof deck. The joints in the roof sheathing are sealed, so if wind strips off the roof covering, rain cannot pour through the gaps. IBHS says this can reduce water entry by up to 95%.
• Ring-shank nails. Sheathing is fastened with 8d ring-shank nails at closer spacing instead of smooth nails. IBHS testing indicates this can roughly double uplift resistance.
• Locked-down edges. A wider drip edge and a fully adhered starter strip help keep wind from getting under the roof edge.
• Rated roof covers. Asphalt shingles must carry an ASTM D3161 Class F or ASTM D7158 Class H wind rating, and all roof systems must be rated for the design pressures at the site.

Hail supplement

An optional hail supplement targets hail-prone regions. It calls for asphalt shingles rated "Good" or "Excellent" in IBHS's own hail impact ratings, UL 2218 Class 4 for metal and low-slope roofs, and FM 4473 Class 4 for tile.

Insurance and public programs

Several US states have linked insurance rules and grants to FORTIFIED. Alabama is the best-known case: a 2009 state insurance law requires insurers to offer premium discounts for homes certified as FORTIFIED, with savings reported of up to 50% on the wind portion of a policy, and a state grant program has paid for FORTIFIED roofs in coastal counties. Georgia, Mississippi, North Carolina and Oklahoma have passed similar insurance laws, and other states, including Louisiana and South Carolina, encourage FORTIFIED construction. Discount levels and eligibility differ by state and insurer.

Relationship to building codes

FORTIFIED is not a building code. In most places it is an above-code option chosen by homeowners, builders or grant programs. Some features, such as sealed roof decks, have been proposed or adopted in code updates in hurricane-prone states.