Building standards: how construction drives coverage
Construction is the foundation underwriters price on. Codes, the FORTIFIED standard, roof age, and opening protection determine how a building survives a catastrophe — and how it insures.
Why building standards drive your insurance
Of the four things underwriters price on — Construction, Occupancy, Protection, and Exposure — construction is the foundation. How a building is built and to what standard determines how it performs in a fire, a hurricane, or a hailstorm, and that performance is exactly what carriers are pricing. A building constructed and maintained to a recognized resilience standard is easier to place, tends to earn better terms, and in catastrophe-exposed markets can be the difference between an offer and a decline.
This page covers the standards that matter most: modern building codes, the FORTIFIED resilience standard, and the construction and roofing choices that most affect both loss and insurability.
Building codes: the baseline
Building codes set the minimum. Modern codes — and how strictly a jurisdiction enforces them — strongly predict how a building survives a catastrophe. Two code-related points matter for insurance:
- Year built and code edition. A building built or updated to a recent code edition generally performs better and is viewed more favorably by underwriters than an older structure built to weaker standards.
- Ordinance-or-law exposure. After a loss, current codes may require you to rebuild to a higher standard than the original construction — and standard policies limit how much of that upgrade cost they'll pay. Ordinance or law coverage (available by endorsement) closes that gap. It's one of the most overlooked coverages in older buildings.
FORTIFIED: the resilience standard above code
FORTIFIED is a construction and re-roofing standard from the Insurance Institute for Business & Home Safety (IBHS) that strengthens a building against hurricane, high wind, and hail — going beyond typical code minimums. It comes in three commercial tiers — FORTIFIED Roof, Silver, and Gold — each building on the last:
- FORTIFIED Roof — the foundation of the program. It requires a Class A fire-rated roof cover installed as new construction or full re-roof (stripped to the deck — re-covering isn't permitted), a sealed roof deck secondary water barrier, enhanced edge securement, and roof systems engineered to meet code wind-uplift loads (ASCE 7, minimum Exposure Category C or D). The roof is the first thing to fail in a windstorm, so this tier delivers the most protection per dollar.
- FORTIFIED Silver — builds on the roof with protection for the rest of the envelope: impact-rated windows, doors, and opening protection rated to the building's design pressures, plus securement of roof-mounted equipment (a major source of commercial wind loss) and other attachments.
- FORTIFIED Gold — adds a continuous load path: an engineered series of connections that carries wind forces from the roof through the walls to the foundation so the building resists the storm as a single unit, eliminating the "weak links" where failures start. The most complete level of protection.
A FORTIFIED designation is verified by a certified evaluator and is time-limited (re-evaluation keeps it current). Because it's an insurance-industry standard, a FORTIFIED designation is recognized by underwriters and can materially improve availability and terms in wind-exposed markets.
Even if the roof covering blows off in a storm, a sealed roof deck keeps water out of the building — preventing the interior and contents damage that drives the largest hurricane claims. It's the highest-value single upgrade in wind country.
A FORTIFIED Commercial designation is issued by an IBHS-certified evaluator and is valid for five years, with re-evaluation required to keep it current — low-slope commercial roofs may need in-situ moisture or uplift testing at re-designation. Because the standard is designed and recognized by the insurance industry, the designation is a credential underwriters understand.
The six ISO construction classes
Underwriters classify every building into one of six construction classes defined by ISO — the framework that, more than almost anything else, determines how a building rates for fire and how it's viewed for wind. In broad terms, classes improve as the structure moves from combustible to noncombustible to fire-resistive:
Frame
Combustible exterior walls — wood or similar (including brick-veneer or stucco over wood frame). Typically smaller, low-rise buildings. The most combustible class and generally the highest-rated for fire.
Joisted Masonry (JM)
Masonry load-bearing exterior walls (block, brick, concrete) with a combustible (wood) floor and roof. The walls resist fire; the roof and floors don't.
Noncombustible (NC)
Walls, floors, and roof of noncombustible materials — commonly steel frame with metal or masonry infill. Pre-engineered metal buildings are typical. Materials don't burn but have limited fire-resistance rating.
Masonry Noncombustible (MNC)
Masonry load-bearing walls (block, reinforced masonry, tilt-up concrete) with noncombustible floors and roof (commonly concrete on steel deck). A common, well-regarded commercial class.
Modified Fire-Resistive
Masonry or fire-resistive walls, floors, and roof with a fire-resistance rating of one hour or more but less than two. A step up from MNC in fire performance.
Fire-Resistive
Walls, floors, and roof of masonry or fire-resistive materials rated at two hours or more. Common in high-rises. The highest class — best fire performance and generally the most favorable rating.
Wind performance doesn't track fire class perfectly — a masonry building can still lose a poorly attached roof — which is why construction class, roof attachment, and opening protection are all assessed together. But knowing your class is the starting point for any underwriting conversation.
Construction class drives the base fire rate and shapes appetite before any other factor. It's usually the first thing on a submission — so having your class (and roof age, and year built) documented speeds a cleaner, better quote.
Construction factors that move your risk
Beyond formal standards, specific construction attributes consistently affect both loss and pricing:
- Construction class. Frame vs. joisted masonry vs. masonry non-combustible vs. fire-resistive — each performs differently in fire and wind, and each rates differently. Non-combustible and fire-resistive construction generally earns better terms.
- Roof age and covering. The single most scrutinized attribute in many markets. Impact-resistant roofing and a recent roof age materially help; an aging roof can drive higher deductibles, exclusions, or declinations.
- Opening protection. Impact-rated glazing and shutters keep the envelope intact under wind and debris.
- Protective systems. Sprinklers, fire alarm, and monitored security round out the "Protection" picture that pairs with construction quality.
The building standards playbook
- Know your construction class, year built, and roof age — these are the first things an underwriter asks, and having them documented speeds a better quote.
- Pursue FORTIFIED (at least FORTIFIED Roof / sealed roof deck) when re-roofing in wind country — it's the highest-value resilience upgrade and is a credential carriers recognize.
- Add ordinance or law coverage for older buildings, so a code-driven rebuild doesn't become an uninsured cost.
- Document upgrades — roof certifications, FORTIFIED designations, code-compliance records — and bring them to submission.
Frequently asked questions
ISO defines six commercial construction classes: Frame (1), Joisted Masonry (2), Noncombustible (3), Masonry Noncombustible (4), Modified Fire-Resistive (5), and Fire-Resistive (6). They range from combustible to fire-resistive and are a primary factor in how a building rates for property insurance.
Yes. Construction is one of the core factors underwriters price on. A building built or upgraded to a recognized standard — modern codes, FORTIFIED, impact-resistant roofing — generally sees better availability and terms, though pricing is always determined by underwriting on the full risk.
A resilience construction and re-roofing standard from the Insurance Institute for Business & Home Safety (IBHS) that strengthens buildings against wind, hurricane, and hail beyond typical code. It has three commercial tiers — FORTIFIED Roof (Class A roof cover and sealed roof deck), Silver (opening protection and roof-mounted equipment), and Gold (continuous load path) — verified by an IBHS-certified evaluator and valid for five years.
A secondary water barrier installed under the primary roof covering. If the covering is lost in a storm, the sealed deck keeps water out of the building — preventing the interior and contents damage that drives the largest hurricane claims. It's a core part of the FORTIFIED Roof standard.
Coverage (available by endorsement) that pays the extra cost of rebuilding to current codes after a loss — costs a standard policy limits. It's especially important for older buildings, where modern codes may require significant upgrades during a rebuild.