In a hurricane the roof usually lets water in long before it lets go.
Steep-slope and low-slope · single-family and small multifamily
The photographs after a storm show roofs peeled to the deck. FEMA's own account of what it finds afterwards is duller and more expensive: envelope damage and wind-driven rain, on houses whose roofs are still there.
What actually decides how a roof does in a hurricane?
Hurricane water damage does not wait for the covering to blow off: FEMA reports that structural failures are less common than envelope damage and wind-driven rain intrusion. Rain is driven through gaps in the deck, through attic vents, and around openings. A sealed roof deck, a secured edge, and protected openings decide how a house does — more than any mph number, which is marketing rather than a design determination.
The short versionSection link
Nothing below is a determination for a specific building. Design wind speed, exposure category, and every requirement that follows from them are set by the code edition your jurisdiction has actually adopted, and confirmed by your authority having jurisdiction.
- What usually fails first
- The building envelope and wind-driven rain intrusion — not the structureFEMA P-804 states plainly that structural failures are not as common as other wind-related damage such as damage to the building envelope or wind-driven rain intrusion. That single sentence is the reason this page is organised the way it is.
- Where uplift is worst
- Corners, edges, and ridge linesFEMA P-499 Fact Sheet 7.1. It is also why FEMA P-804 specifies a tighter deck-fastener schedule inside a four-foot edge zone than in the field of the roof.
- Water through an open deck
- IBHS estimates nine bathtubs per inch of rainIBHS: the equivalent of nine bathtubs of water can enter a home for every inch of rain that falls on a traditional roof deck where space between the boards is exposed — and there are four ways to cover those gaps that reduce the risk by as much as 95 percent.
- When shingles start to go
- As low as 60 mph on aged materialIBHS testing, quoted in its own research release. A shingle that has not yet sealed — which can take one to two weeks in good conditions and one to two months or more in poor ones — is more vulnerable still.
- A broken window is a roof problem
- Sudden internal pressurization can cause roof lossFEMA P-499 Fact Sheet 6.2: if the envelope is breached, sudden pressurization of the interior may result in major structural or non-structural damage, e.g. roof loss.
- Two different mph numbers
- Storm categories are 1-minute averages; design wind speed is a 3-second gustNOAA reports hurricane intensity as the highest one-minute average wind at 10 metres. FEMA's coastal guidance states design wind speeds as 3-second peak gusts. The two numbers are not interchangeable and neither is a product rating.
- Vents are a water entry route
- Hurricane winds drive large amounts of water through attic ventilation openingsFEMA P-499 Fact Sheet 7.5, which adds that the accumulating water soaks insulation and can lead to mould growth and, in some cases, to the collapse of ceilings.
- What a product approval is
- A jurisdiction's document about one product, with an expiry dateA Miami-Dade Notice of Acceptance says it is issued for use in Miami-Dade County and other areas where allowed by the authority having jurisdiction, and that it is not valid after its stated expiration date. It is not a national rating.
Spend on the deck, the edge, and the openings — and where that advice is wrongSection link
The position on this page is that the money goes into what keeps water out of an intact-looking house, in this order: deck attachment, a sealed deck, the roof edge, vents, and openings. There are real buildings where that is not the right first move.
Best when
- The roof is due for replacement anyway. Deck re-nailing, a sealed deck, and a proper edge are only cheap while the covering is off, and expensive at every other moment.
- The house is in a windborne-debris region or close to it, where FEMA's guidance and adopted codes already treat opening protection as a requirement rather than an upgrade.
- The building has a wood-board deck with gaps between the boards. That is the specific case IBHS quantifies at nine bathtubs of water per inch of rain.
- The attic contains ductwork, an air handler, or finished storage, so water that gets past the deck lands on something expensive rather than on a bare joist bay.
- There is a state or utility retrofit grant programme. Alabama's Strengthen Alabama Homes programme, for example, funds retrofits to the FORTIFIED standard; the insurance department reports more than 8,700 homes fortified under its grants, inside a statewide total of more than 50,000 FORTIFIED designations.
- You intend to hold the building for long enough that the work is amortised over more than one storm season.
Think twice if
- The real exposure is storm surge or inland flooding rather than wind. The National Hurricane Center calls surge the greatest threat to life and property along the coast, and calls flooding the major threat for people living inland. A sealed roof deck does nothing about either. Elevation, flood insurance, and siting are different projects.
- The proposal sells a full self-adhered membrane and nothing else. Sealing the deck without first checking and improving deck-to-framing attachment is protecting a panel that can still leave the building; FEMA P-804 sequences the fastening first, deliberately.
- Someone proposes converting a vented attic to an unvented one as part of the same job. FEMA calls an unvented attic a reliable way to keep wind-driven rain out, and in the same breath calls the conversion controversial, says it must be done with the advice of knowledgeable experts, and warns that one side effect may be voiding the roof covering warranty.
- The covering is new and sound. Most of this work needs the covering off, and tearing off a serviceable roof to reach the deck is a decision with its own arithmetic.
- The house is a HUD-certified manufactured home. It is built to a federal standard rather than to a locally adopted building code, and the retrofit guidance discussed here explicitly excludes manufactured homes.
- You are in a historic district or under an HOA covenant that constrains materials, edge profiles, and vent products. Confirm what is approvable before anyone specifies a product.
- You are selling within the year. The right answer for the building and the right answer for a short ownership horizon are different answers, and it is more honest to say so than to pretend they converge.
What changes the answer
- The design wind speed and exposure category at the site, which are the inputs everything else is derived from — and which are set by the adopted code edition, not by a contractor's judgement.
- Whether the site is inside a windborne-debris region. That is a mapped determination your building department makes, not one you make from a coastline.
- Deck type. A wood-board deck with gaps behaves nothing like continuous structural panel sheathing, and the sealing method that suits one is not the one that suits the other.
- Roof geometry. A hip roof has no gable end wall to brace; a gable does, and FEMA treats gable-end overhangs and gable-end walls over four feet tall as separate retrofits.
- Whether the garage door is rated. FEMA notes garage doors are commonly damaged in high-wind events and that many labels carry no wind pressure rating at all.
- Distance from saltwater. Inside 3,000 feet, FEMA calls for stainless or hot-dip galvanised fasteners and treats aluminium soffits as a corrosion problem in their own right.
- Whether your jurisdiction runs a product approval regime, and therefore whether the specified assembly has to appear on a list before it can be installed.
- Your insurer. Premium credits, deductible structures, and what a carrier will recognise vary by carrier and by state, and none of it is decided by this page.
Wind does not press on a roof evenly, and rain does not wait for the roof to leaveSection link
Two things run at once in a hurricane: suction that is concentrated at the corners and edges of a roof, and rain being driven horizontally at whatever the wind can find a way through. They are separate problems with separate fixes, and contractor copy usually collapses them into one.
1 · Suction, not pressure, and not evenly spread
Wind flowing over a roof accelerates at the corners and edges and separates from the surface, which produces suction — the roof is being pulled up, not pushed down. FEMA’s coastal fact sheet on roof sheathing puts the consequence in one line: the highest uplift forces occur at roof corners, edges, and ridge lines. That is the whole reason for the concept of a pressure zone: a roof is treated as a field, a perimeter, and a set of corners, and attachment gets denser as you move outward.
FEMA P-804 turns that into a schedule. Its deck-refastening tables give one fastener spacing inside a four-foot roof edge zone and a looser one outside it, and it illustrates those zones on both gable and hip roofs. The same logic runs through every part of the assembly: it is why edge metal and the starter course matter out of all proportion to their cost, and why damage photographs so often show a roof that has unzipped from one corner inward rather than lifted off as a sheet.
2 · The deck is the part that has to stay
FEMA calls sheathing loss one of the most common structural failures in hurricanes, and warns that the loss of just one panel can lead to total building failure. That is why the first move in its Basic mitigation package is not a better shingle. It is securing the roof deck to the framing with more and better fasteners — ring-shank nails rather than smooth, full round heads rather than clipped, and no staples.
This is also the one upgrade that is only available for a few hours in a building’s life. Deck re-nailing happens while the deck is bare during a tear-off, and it is priced as a separate line item or it does not happen at all.
3 · Now the part almost nobody sells: the deck leaks
A steep-slope roof covering is a water-shedding assembly. Under a horizontal wind load, water does not shed — it is driven sideways and upward, into and through every joint it can reach. If the covering is lifted, torn, or simply not yet sealed, what stands between that water and the ceiling below is whatever is on the deck.
IBHS quantifies the case that makes this vivid. On a traditional wood-board deck with gaps between the boards, its research estimates the equivalent of nine bathtubs of water entering a home for every inch of rain falling on it. Its answer is a sealed roof deck — and IBHS states that there are four ways to cover those gaps and reduce that risk by as much as 95 percent.
FEMA has its own name for the same idea. Its coastal fact sheet 7.2 exists, in its own words, to give recommended practices for using roofing underlayment as an enhanced secondary water barrier, and it ranks three methods in decreasing order of resistance to long-term weather exposure following the loss of the roof covering. Those three methods are set out further down this page, with what each one costs the building in exchange.
4 · Vents are holes, and hurricanes find holes
Attic ventilation is a building-science requirement in most assemblies and a water entry route in a hurricane, both at once. FEMA is direct about it: hurricane winds can drive large amounts of water through attic ventilation openings, the accumulating water soaks insulation, and that can lead to mould growth and, in some cases, to the collapse of ceilings. It lists soffit vents, ridge vents, gable end vents, off-ridge vents, gable rake vents, and turbines as devices observed to admit water, some of which have also been observed to blow off.
Soffits deserve their own sentence. FEMA notes that some water gets in through almost any soffit vent, but that the amount increases dramatically when the soffit material itself is missing. A vinyl or aluminium soffit panel that lets go turns a ventilation opening into an open hole under the eave, pointed straight into the attic.
There is a legitimate alternative and a large caveat attached to it. FEMA calls an unvented attic the most conservative approach to preventing wind-driven rain from entering the attic, and a reliable way to do it where the building code allows it and the climate and interior humidity suit it. In the same fact sheet it calls unvented attics controversial, says a conversion on an existing house has to be done very carefully with the advice of knowledgeable experts, and notes that one side effect may be voiding the warranty for the roof covering. Both a vented and a correctly designed unvented assembly are legitimate. Neither is a product you buy; the arithmetic and the design questions live on the ventilation guide.
5 · A failed window can lift a roof from the inside
This is the interaction that makes opening protection a roofing subject rather than a window subject. FEMA states it plainly: if the envelope is breached, sudden pressurization of the interior may result in major structural or non-structural damage — it gives roof loss as its example — and will lead to significant interior and contents damage from wind-driven rain.
Think of the roof as being pulled up from outside by suction while the house behind a broken window is being inflated from inside. The two loads add. Garage doors are the most common way this happens: FEMA notes they represent large unreinforced openings, are commonly damaged in high-wind events, could allow a building to be pressurized if breached, and that many garage door labels do not include a wind speed or wind pressure rating at all.
Two corrections come attached. First, covering an opening is not the same as relieving the pressure on it. FEMA P-804 notes that systems protecting glazing from debris impacts are often not rated to reduce wind pressures on the opening they protect — a pressure rating on such a system is typically a rating against its own blow-off or deflection — and Fact Sheet 6.2 adds that the glazing and its frame should therefore still be designed for the full design loads. Second, shutters are not a rain measure: FEMA says the addition of shutters will not eliminate the potential for wind-driven rain entering the building, and that it should be assumed that a shutter will not significantly decrease the wind-driven rain demand on the glazed assembly.
6 · The evidence that the water half is the expensive half
This is not only a laboratory argument. After Hurricane Sally in 2020, the Alabama Department of Insurance issued a data call and the University of Alabama’s Center for Risk and Insurance Research analysed the result: 40,195 single-family owner-occupied wind policies, of which 8,629 reported claims totalling $181,466,480.
Two findings from that report are worth carrying away. The first is that rainfall demonstrated a higher correlation with the damage ratio than either of the wind measures the study used. The second is the report’s own explanation of why: on its own, rainfall is less likely to damage a house than wind speed or wind duration, because rainfall cannot easily penetrate the envelope of a house. However, combined with wind, rainfall increases damage once the envelope begins to fail. The roof does not have to leave for the house to be ruined. It only has to start letting go.
Four numbers that all end in mph, and what each one actually measuresSection link
Almost every misunderstanding about hurricane roofing starts here: four different quantities are all quoted in miles per hour, they are not interchangeable, and only one of them is about your building.
| The number | What it actually measures | What it cannot tell you |
|---|---|---|
| Storm category (Saffir-Simpson) | NOAA's 1-to-5 rating, based only on a hurricane's maximum sustained wind speed — the highest one-minute average wind at 10 metres with unobstructed exposure. Category 3 is 111–129 mph on that basis. | Anything about your site. NOAA states the scale does not account for storm surge, rainfall flooding, or tornadoes, and a one-minute average is not the gust that loads a roof. |
| Gust | NOAA describes a gust as a 3 to 5 second burst of wind higher than the maximum sustained wind. Reported gusts are what an anemometer recorded at a specific station. | What the wind did at your house. Terrain, height, and shielding change it over a few hundred feet — which is what an exposure category exists to account for. |
| Design (basic) wind speed | A mapped value in the adopted code, stated as a 3-second peak gust, that is combined with exposure category, height, geometry, risk category, enclosure, and pressure zone to produce actual design pressures. | Nothing on its own. It is an input. FEMA also notes the mapped speeds changed between ASCE 7 editions — 110 and 120 mph under ASCE 7-05 correspond to 139 and 152 mph under ASCE 7-10 for ordinary buildings — so the edition matters as much as the number. |
| A shingle's wind class | A laboratory result on new material at a stated fastening pattern. FEMA points to UL 2390, whose classes are D (90 mph), G (120 mph) and H (150 mph), and says to select a class at or above the basic wind speed the building code specifies. | Whether the roof will hold. FEMA says in the same fact sheet to use ratings to choose among shingles but not to rely on them for performance, and lists conditions — Exposure D, over 60 feet, Risk Category III or IV, abrupt topography — where the class stops being sufficient on its own. |
Read this table one item at a time
Storm category (Saffir-Simpson)
- What it actually measures
- NOAA's 1-to-5 rating, based only on a hurricane's maximum sustained wind speed — the highest one-minute average wind at 10 metres with unobstructed exposure. Category 3 is 111–129 mph on that basis.
- What it cannot tell you
- Anything about your site. NOAA states the scale does not account for storm surge, rainfall flooding, or tornadoes, and a one-minute average is not the gust that loads a roof.
Gust
- What it actually measures
- NOAA describes a gust as a 3 to 5 second burst of wind higher than the maximum sustained wind. Reported gusts are what an anemometer recorded at a specific station.
- What it cannot tell you
- What the wind did at your house. Terrain, height, and shielding change it over a few hundred feet — which is what an exposure category exists to account for.
Design (basic) wind speed
- What it actually measures
- A mapped value in the adopted code, stated as a 3-second peak gust, that is combined with exposure category, height, geometry, risk category, enclosure, and pressure zone to produce actual design pressures.
- What it cannot tell you
- Nothing on its own. It is an input. FEMA also notes the mapped speeds changed between ASCE 7 editions — 110 and 120 mph under ASCE 7-05 correspond to 139 and 152 mph under ASCE 7-10 for ordinary buildings — so the edition matters as much as the number.
A shingle's wind class
- What it actually measures
- A laboratory result on new material at a stated fastening pattern. FEMA points to UL 2390, whose classes are D (90 mph), G (120 mph) and H (150 mph), and says to select a class at or above the basic wind speed the building code specifies.
- What it cannot tell you
- Whether the roof will hold. FEMA says in the same fact sheet to use ratings to choose among shingles but not to rely on them for performance, and lists conditions — Exposure D, over 60 feet, Risk Category III or IV, abrupt topography — where the class stops being sufficient on its own.
A marketing “rated to 130 mph” claim is the fourth row of this table being quoted as if it were the third. It is not a code determination, it is not about your building, and no product rating ever is.
Three ways to seal a roof deck, and what each one costs youSection link
FEMA ranks three underlayment methods in decreasing order of resistance to long-term weather exposure after the covering is lost, and states where each is appropriate. The fourth column is the one no brochure prints.
| Method | What goes on the deck | Where FEMA advocates it | What it costs you |
|---|---|---|---|
| Full self-adhered membrane | One layer of self-adhering modified bitumen meeting ASTM D1970 over the whole roof area, sealed to deck penetrations with roof tape or asphalt roof cement, then a bond-break layer of ASTM D226 Type I (#15) felt, then the covering. | FEMA P-499 Option 1: the greatest reliability for long-term exposure following loss of the roof covering. Advocated in heavily populated areas where the design wind speed is 120 mph or more — the equivalent of 152 mph under ASCE 7-10 for Risk Category II buildings. | The highest material cost of the three, and a permanent change to the deck. The bond-break layer is not optional: FEMA P-804 specifies it to stop the covering bonding to the membrane, which damages the sheathing when the covering is replaced later. It also makes the top of the deck vapour-tight, which is a design question in some assemblies rather than a product swap. |
| Taped seams under two layers of felt | Self-adhering modified bitumen tape at least 4 inches wide over every sheathing joint, rolled, with penetrations sealed; then two layers of ASTM D226 Type II (#30) with offset side laps, secured with low-profile capped-head nails or tin-caps at about 6 inches on centre along laps and 12 inches on centre in the field. | FEMA P-499 Option 2: the middle of the three, between the full membrane and the single-felt option. | More labour in the taping step than a conventional underlayment, and it depends on the tape being rolled properly onto a broom-cleaned deck. The felt itself can still blow off; what remains is the sealed joint line, which is the part doing the work. |
| Taped seams under one layer of felt | The same 4-inch tape over sheathing joints and around penetrations, then a single layer of ASTM D226 Type I (#15) felt, tacked to hold it until the shingles go on. | FEMA P-499 Option 3: described as providing limited protection, and advocated only in areas with modest population density and a design wind speed of 110 mph or less — 139 mph under ASCE 7-10 for Risk Category II. | FEMA states the limit itself: the underlayment has limited blow-off resistance, water infiltration resistance is provided by the taped and sealed sheathing panels, and the option is intended for use where temporary or permanent repairs are likely within several days of the covering blowing off. That is a real assumption about how fast a contractor can reach you after a regional storm. |
| Sealing without replacing the covering | FEMA P-804's second Basic-package option: securing deck attachment and providing a secondary water barrier using spray polyurethane foam adhesive at the deck-to-framing connections, without removing the roof covering. | P-804 lists it as a legitimate route for a house whose covering is not due for replacement, and points to South Carolina Sea Grant guidance on using structural adhesive to strengthen sheathing attachment. | P-804 says Option 1 is preferred, because replacing the covering is what ensures the deck-to-framing connections are actually checked and an adequate underlayment installed — and notes that homes retrofitted this way will likely receive a smaller insurance premium reduction. It is contractor work in a confined attic, not a homeowner job. |
Read this table one item at a time
Full self-adhered membrane
- What goes on the deck
- One layer of self-adhering modified bitumen meeting ASTM D1970 over the whole roof area, sealed to deck penetrations with roof tape or asphalt roof cement, then a bond-break layer of ASTM D226 Type I (#15) felt, then the covering.
- Where FEMA advocates it
- FEMA P-499 Option 1: the greatest reliability for long-term exposure following loss of the roof covering. Advocated in heavily populated areas where the design wind speed is 120 mph or more — the equivalent of 152 mph under ASCE 7-10 for Risk Category II buildings.
- What it costs you
- The highest material cost of the three, and a permanent change to the deck. The bond-break layer is not optional: FEMA P-804 specifies it to stop the covering bonding to the membrane, which damages the sheathing when the covering is replaced later. It also makes the top of the deck vapour-tight, which is a design question in some assemblies rather than a product swap.
Taped seams under two layers of felt
- What goes on the deck
- Self-adhering modified bitumen tape at least 4 inches wide over every sheathing joint, rolled, with penetrations sealed; then two layers of ASTM D226 Type II (#30) with offset side laps, secured with low-profile capped-head nails or tin-caps at about 6 inches on centre along laps and 12 inches on centre in the field.
- Where FEMA advocates it
- FEMA P-499 Option 2: the middle of the three, between the full membrane and the single-felt option.
- What it costs you
- More labour in the taping step than a conventional underlayment, and it depends on the tape being rolled properly onto a broom-cleaned deck. The felt itself can still blow off; what remains is the sealed joint line, which is the part doing the work.
Taped seams under one layer of felt
- What goes on the deck
- The same 4-inch tape over sheathing joints and around penetrations, then a single layer of ASTM D226 Type I (#15) felt, tacked to hold it until the shingles go on.
- Where FEMA advocates it
- FEMA P-499 Option 3: described as providing limited protection, and advocated only in areas with modest population density and a design wind speed of 110 mph or less — 139 mph under ASCE 7-10 for Risk Category II.
- What it costs you
- FEMA states the limit itself: the underlayment has limited blow-off resistance, water infiltration resistance is provided by the taped and sealed sheathing panels, and the option is intended for use where temporary or permanent repairs are likely within several days of the covering blowing off. That is a real assumption about how fast a contractor can reach you after a regional storm.
Sealing without replacing the covering
- What goes on the deck
- FEMA P-804's second Basic-package option: securing deck attachment and providing a secondary water barrier using spray polyurethane foam adhesive at the deck-to-framing connections, without removing the roof covering.
- Where FEMA advocates it
- P-804 lists it as a legitimate route for a house whose covering is not due for replacement, and points to South Carolina Sea Grant guidance on using structural adhesive to strengthen sheathing attachment.
- What it costs you
- P-804 says Option 1 is preferred, because replacing the covering is what ensures the deck-to-framing connections are actually checked and an adequate underlayment installed — and notes that homes retrofitted this way will likely receive a smaller insurance premium reduction. It is contractor work in a confined attic, not a homeowner job.
These are FEMA's December 2010 recommendations, not code requirements, and the wind speeds are stated in the ASCE 7 editions FEMA used. Fastener metal changes near the coast: within 3,000 feet of saltwater FEMA recommends stainless steel or hot-dip galvanised fasteners for underlayment attachment. Confirm what your jurisdiction actually requires with your building department before specifying any of this.
What a product approval document actually says about itselfSection link
A few jurisdictions run formal product approval regimes. Reading one of their documents is the fastest cure for believing that a wind rating is a national credential.
Florida is the clearest example, and its statute does something unusual: it makes approval the condition of the advertising, not only of the installation. Section 553.842 of the Florida Statutes provides that a product may not be advertised, sold, offered, provided, distributed, or marketed as hurricane, windstorm, or impact protection from wind-borne debris unless it is approved under that section — and that anyone who does so anyway is subject to the Florida Deceptive and Unfair Trade Practices Act. Roofing is one of the named categories.
The statute also settles the relationship between state and local authority. Statewide approval precludes a local jurisdiction from requiring further testing or evidence as a condition of using the product, so long as the product is being used consistent with the conditions of its approval — and a building official may still deny a local application, by written report, on the ground that the application is inconsistent with the approval. Both halves matter. The approval travels; the use has to match it.
Miami-Dade County runs its own Product Control section and issues a Notice of Acceptance. It is worth reading what one says about itself, because the standing language is the whole lesson. A current NOA for a roofing underlayment states that the documentation was reviewed and accepted to be used in Miami-Dade County and other areas where allowed by the Authority Having Jurisdiction; that the NOA is not valid after the expiration date stated on it; that renewal is considered only on application and only where the applicable building code has not changed in a way that negatively affects the product; that any revision to the materials, use, or manufacture terminates it; and that misuse of the NOA as an endorsement for sales or advertising automatically terminates it. The one on this page’s source list was approved in September 2022 and expires in September 2027.
Two things follow. An approval is a document about a named product from a named manufacturer, installed a named way — the same NOA specifies the head lap, the end lap, the fastener, and the spacing. And an approval is a document with a date on it. “Miami-Dade approved” on a brochure, with no number and no expiry, is not a claim you can check, which is the only kind of claim worth anything.
Most of the country has no regime like this at all. Where there is none, the equivalent question is the ordinary one: which adopted code edition applies, what does it require of this assembly, and will the building official pass it? Ask the authority having jurisdiction, not the salesperson.
The week after, which is where most of the money is lostSection link
The decisions that go wrong after a hurricane are made under time pressure, with a wet ceiling, by people who have never bought a roof before. Knowing the sequence in advance is most of the defence.
The sequence that protects you
Document before anyone touches anything. Photographs from the ground on every elevation, wide and then close. Interior photographs of every stain, with a date. Keep receipts for anything you spend, including a hotel. This is the record every later conversation — with an insurer, a contractor, or a building department — will be argued from.
Stabilise, do not repair. Emergency covering is about stopping ongoing intrusion, not about fixing the roof, and it is work to buy rather than attempt. The emergency tarping page covers where the line is and what the first hours actually require.
Expect the driveway visit. After a regional storm the supply of roofing labour is fixed and the demand is not, which is what produces door-knocking, same-day contracts, and deposits requested before a scope exists. The verification steps do not change because it is an emergency: licence or registration, a current certificate of insurance naming the carrier, a written scope, and references you actually call. They are set out on how to check a roofing contractor.
Know that a storm scope and a good roof are different documents. An insurance scope describes what a carrier considers a covered loss on this policy. It is not a specification for a roof that will do better next time, and the upgrades on this page — deck re-nailing, a sealed deck, better edge metal, rated vents — are usually not in it. If you want them, they are a conversation you start, priced separately, at the moment the deck is bare. That moment does not come round again until the next tear-off.
Do not let the repair erase the evidence. Before a tear-off begins, photograph the deck: fastener pattern, board gaps, existing underlayment, and any water staining on the sheathing. Ten minutes there answers questions nobody can answer afterwards.
What the season is, so the calendar is not a surprise
The Atlantic hurricane season runs from 1 June to 30 November. NOAA gives the 1991–2020 average season as 14 named storms, 7 hurricanes, and 3 major hurricanes, with the peak on 10 September and most activity between mid-August and mid-October. Roofing work booked in April is work done on a dry deck by a contractor who is not triaging; the same work booked in September is not.
And the exposure is not only coastal. NOAA notes that winds can stay above hurricane strength well inland — Hurricane Charley in 2004 produced gusts over 100 mph across central Florida — and that flooding, from rainfall often in excess of 6 inches, is the major threat for people living inland. A house two hundred miles from the water has a hurricane exposure. It is a different one.
What changes this on a real buildingSection link
- Wind
Wind performance is a property of a building on a site, not of a product in a box. The basic wind speed mapped for the location is only the first input; exposure category, mean roof height, building geometry, risk category, whether the building is treated as enclosed or partially enclosed, which pressure zone a given fastener sits in, and the actual tested assembly all move the answer. FEMA describes the exposure categories in ordinary language: B is urban, suburban and wooded; C is open terrain, which includes shoreline in hurricane-prone regions; D is flat, unobstructed exposure to wind flowing over open water.
Two houses on the same street can land in different exposure categories, and two roofs of the same shape can need different fastener schedules because one is taller. FEMA P-804 points readers to the Applied Technology Council’s wind speed website to find the applicable speed for a location; it is a starting point for a conversation with a building department, not a substitute for one.
A marketing “130 mph roof” is not a code determination and is not a claim about your building. It is, at best, a class rating from a laboratory test on new material at a stated fastening pattern. FEMA's own coastal guidance says to use wind-resistance ratings to choose among shingles, but not to rely on ratings for performance.- Code and jurisdiction
There is no nationwide building code for site-built houses in the United States. Everything on this page that sounds like a requirement is either FEMA guidance, which is not adopted law anywhere, or a specific jurisdiction’s rule that applies in that jurisdiction. Which code edition is in force, whether it was amended locally, whether your address sits inside a mapped windborne-debris region, and what a re-roof triggers as opposed to new construction are four separate local questions with four local answers.
Two of them are worth asking out loud before a contract is signed. Does the work trigger a requirement to bring anything else up to current code? And is the specified assembly one this jurisdiction will accept — which, in a product approval state, is a documentary question with a documentary answer.
Record the jurisdiction, the adopted edition, the amendments, the effective date, and the official URL for any code claim, and confirm it with the authority having jurisdiction. Nothing on this page is a code determination for your building.- Moisture and ventilation
Sealing a deck changes how it dries. A full self-adhered membrane over the whole roof area is a vapour-tight layer above the sheathing, and where it goes on an assembly that was designed to dry upward, that is a building-science decision rather than a product substitution. FEMA’s own underlayment guidance distinguishes between southern and northern climates in the sequence it recommends, which is a signal that climate is part of the specification and not an afterthought.
The same applies in the other direction. Making an attic unvented to keep wind-driven rain out removes the ventilation that was managing moisture from below. Both approaches are legitimate; neither survives being improvised on a Tuesday afternoon by whoever is already on the roof.
Vented and correctly designed unvented assemblies are both recognised approaches, and there is no universal ventilation ratio. Whether an unvented assembly is permitted at all, and what it requires, depends on the adopted code edition, the climate zone, and the assembly. Confirm with the authority having jurisdiction, and treat a conversion as design work.- Structural weight
Behind the envelope there is a load path question: whether the uplift on the roof is transferred through roof-to-wall connections, through the walls, and into the foundation. FEMA puts continuous load path work in its most advanced retrofit package for a reason — it is invasive, and it is best done during substantial renovation or rebuilding.
It also records why it matters at all. Its example of a house whose roof structure was destroyed because the connections could not transfer roof loads to the foundation is a house where the wind speeds were estimated at only 50 mph.
Load path, uplift capacity, and connection design are engineering determinations for a specific building. They are made by a licensed design professional looking at that structure, never by a website and never by a retrofit brochure.- Maintenance
Asphalt shingles rely on a sealant strip that bonds each course to the one below under heat and time. IBHS states that in optimal conditions that takes one to two weeks, and in poor conditions one to two months or more — and that wind can lift unsealed shingles so water seeps underneath them. A roof installed in October in cool, overcast weather may not be a sealed roof when the next storm arrives.
The other maintenance item is the one nobody schedules: after every storm, the ground-level look. Missing or displaced edge metal, a hanging soffit panel, a ridge vent sitting proud, and granules in the gutters are all readable from a driveway.
- Insurance
The Alabama study is the strongest public evidence available that this class of construction changes insurance outcomes: across three analytical approaches, FORTIFIED construction reduced loss frequency by 55 to 74 percent, loss severity by 14 to 40 percent, and loss ratio by 51 to 72 percent in Hurricane Sally. It is worth reading with its own caveats attached. It is one storm, in one state, in one year; 46 percent of the claims in the sample were caused by trees falling on houses, which FORTIFIED is not designed to address; and the study measures insurance outcomes, not the physics of any individual roof.
It is also not disinterested work, and that belongs on the record next to the numbers. The report names its technical support on its own cover: IBHS, which owns and certifies the FORTIFIED programme being evaluated, together with Smart Home America, which promotes it, and RenaissanceRe Risk Sciences. The data call and the analysis came from a state regulator and a university centre, which is why this page cites it at all; the programme owner’s involvement is why it is cited as strong evidence rather than as settled.
Nothing here tells you what your policy covers. Coverage, wind and hurricane deductibles, whether a designation earns a premium credit, and how a claim is settled are governed by the policy document and by the law of the state you are in.
This page cannot promise coverage, a premium credit, a deductible outcome, or a claim result. Those are decided by the carrier, the policy language, and state law and regulation, on the facts of a specific loss.
What the paperwork covers, and what it quietly excludesSection link
- A wind class is a test result, not a promise about your roof
FEMA’s shingle fact sheet recommends determining wind resistance under UL 2390, whose classes are D (90 mph), G (120 mph) and H (150 mph), and says to select a class rating equal to or greater than the basic wind speed specified in the building code. It also says the older methods, ASTM D3161 and UL 997, do not provide adequate information about wind performance even when shingles are tested at the highest fan speed the standard prescribes. And it adds that if the building is in Exposure D, or over 60 feet tall, or a Risk Category III or IV, or sited on an abrupt change in topography such as an isolated hill or escarpment, you consult the manufacturer — because the class alone has stopped answering the question.
- A durability warranty is not a wind warranty
FEMA states it directly: a shingle’s durability rating, indicated by warranty life, is not an indicator of its ability to resist a particular wind speed. A warranty term describes resistance to deterioration from climate conditions. A 50-year shingle is not a 50-year-storm shingle, and the two numbers are unrelated.
- Wind coverage inside a manufacturer warranty is usually narrow
Wind coverage in a manufacturer’s warranty is typically limited in years, limited in speed, conditioned on installation exactly as specified, and often conditioned on a specific fastener count and starter product. Read the actual document for the product and installer in front of you, and read the exclusions before the headline. How roofing warranties actually work covers the general shape of the problem.
- A retrofit can void something else
FEMA notes that one side effect of converting to an unvented attic may be voiding the warranty for the roof covering. The same caution applies to any change that departs from the covering manufacturer’s published installation instructions — including well-intentioned ones. If a proposal enhances an assembly beyond what the manufacturer specifies, ask in writing what that does to the warranty.
Repairability
A sealed deck makes the roof more repairable in one sense and less in another. It buys time after a covering loss — which is precisely the interval FEMA is ranking its three underlayment options against. But a full self-adhered membrane bonds to the deck, and FEMA P-804 specifies a bond-break layer over it for a stated reason: to prevent the roof covering bonding to the membrane, which can damage the sheathing when the covering is replaced later. That is a real, sourced, permanent tradeoff, and it is one a reader should hear from this page rather than from a tear-off crew at the next replacement.
In a product approval jurisdiction, repairability also means availability: a repair has to use components the approval covers, and approvals expire. Keep the approval numbers with the closeout documents.
A warranty is a contract between a reader and whoever wrote it. What it covers, what voids it, whether it transfers, and how it is enforced are set by that document and by the law where the reader lives. Read the actual warranty for the product and the installer in front of you — not a summary of one, including this one.
Questions to ask an installerSection link
These are the questions that separate a proposal written for a hurricane from a proposal written for a driveway conversation. Every one of them has a documentary answer.
What design wind speed and exposure category are you using for this house, and where did you get them?
A good answer names the adopted code edition and the source of the mapped speed, and says which exposure category the site falls in and why. An answer that quotes a product’s mph number back at you has not answered the question, because a product rating is not a site determination.
Will you be re-nailing the deck, and what is the fastener, the pattern in the field, and the pattern in the edge zone?
FEMA’s schedules use different spacings inside and outside a four-foot edge zone, and specify ring-shank nails with full round heads rather than staples or clipped-head nails. If the answer does not distinguish between the field and the edge, the schedule has not been read.
Which deck-sealing method are you proposing, and which of FEMA's three options is it?
Full self-adhered membrane, taped seams under two layers of felt, and taped seams under one layer are three different products at three different prices with three different performance claims. FEMA ranks them and states where each is appropriate. Ask which one this is.
If you are using a full self-adhered membrane, what bond-break layer goes over it?
FEMA P-804 specifies a bond-break underlayment over the membrane so the covering does not bond to it and damage the sheathing at the next replacement. A contractor who has not thought about the roof after this one will not have an answer.
What is going on at the eaves and rakes — the drip edge profile, its gauge, its width, and its fastening?
The roof edge is where wind gets its first purchase and it is the most under-specified line in coastal proposals. IBHS’s FORTIFIED programme calls for a wider drip edge together with a fully adhered starter strip specifically because the two work as a system.
What is happening to the vents and the soffits, and are the replacements rated for wind-driven rain?
FEMA treats vents and soffits as a required part of even its most basic package, and records that much of the damage in past high-wind events has been due to attic ventilation openings that could not resist high-wind forces. “We’ll reuse the existing ones” is an answer, and it tells you something.
Does this jurisdiction require product approval, and can you give me the approval numbers for every component?
In Florida the statute makes statewide approval the condition of advertising a product as hurricane or windstorm protection at all. A contractor working in an approval jurisdiction should be able to produce the numbers without effort, and you should be able to look each one up.
How long after installation will the shingles be sealed, and what happens if a storm arrives before then?
IBHS puts sealing at one to two weeks in optimal conditions and one to two months or more in poor ones. A contractor who acknowledges the interval is being straight with you; one who says the roof is fully rated the day the truck leaves is not.
Require these in writing
- The design wind speed and exposure category used, stated on the proposal
- Deck inspection and re-nailing as a separate priced line, with the fastener type and both spacing schedules
- The deck-sealing method by name, with the referenced standard for each material (for example ASTM D1970 for a self-adhered membrane)
- The bond-break underlayment where a full self-adhered membrane is used
- Drip edge material, gauge, width, lap, and fastener spacing at eaves and rakes
- Starter product by name, and whether it is fully adhered
- Every vent product by name, with its wind and wind-driven-rain performance documentation
- Fastener metal, with stainless or hot-dip galvanised specified where the building is within 3,000 feet of saltwater
- Product approval or Notice of Acceptance numbers, with expiration dates, for every component in an approval jurisdiction
- The covering's wind class and the standard it was tested to, stated as a class rather than as a marketing speed
Misconceptions and failure modesSection link
Common misconceptions
Common belief
My shingles are rated 130 mph, so my roof is good to 130 mph.
What is actually true
A shingle class is a laboratory result for new material at a stated fastening pattern, and it is one component of an assembly that also includes the deck, its attachment, the underlayment, the edge, and the framing beneath. FEMA’s coastal guidance is unusually blunt about the gap: use wind-resistance ratings to choose among shingles, but do not rely on ratings for performance. A roof’s capacity is a calculation for a building; a rating is a label on a bundle.
Common belief
A Category 3 hurricane has 111 to 129 mph winds, so a roof designed for 130 mph is covered.
What is actually true
These are two different measurements wearing the same unit. NOAA reports hurricane intensity as the highest one-minute average wind at an elevation of ten metres, and the Saffir-Simpson scale is a 1-to-5 rating based only on that maximum sustained wind speed. FEMA’s design guidance is written in 3-second peak gusts, and a gust is a short burst higher than the sustained wind. Adding to the confusion, ASCE’s own mapped wind speeds changed between editions: FEMA notes that a 110 mph and a 120 mph speed under ASCE 7-05 correspond to 139 mph and 152 mph under ASCE 7-10 for ordinary buildings. The number alone means nothing until you know which convention it is in.
Common belief
If the shingles stay on, the inside stays dry.
What is actually true
This is the belief this whole page exists to correct. FEMA states that structural failures are not as common as damage to the building envelope and wind-driven rain intrusion. Water is driven through deck joints, through vents and soffits, and around windows and doors while the covering is still in place. The Alabama claims study found rainfall more strongly correlated with the damage ratio than either of its wind measures.
Common belief
Impact windows or shutters will keep the rain out.
What is actually true
They are debris protection, and debris protection is genuinely important — a breach admits both water and a sudden rise in internal pressure. But FEMA says the addition of shutters will not eliminate the potential for wind-driven rain entering the building, and that it should be assumed a shutter will not significantly decrease the wind-driven rain demand on the glazed assembly. Water resistance is a property of the window and its installation, not of the thing bolted over it.
Common belief
It has a Miami-Dade approval, so it is approved everywhere.
What is actually true
A Notice of Acceptance says of itself that it is issued for use in Miami-Dade County and other areas where allowed by the authority having jurisdiction, that it is not valid after its stated expiration date, and that misusing it as an endorsement for sales or advertising automatically terminates it. Approval regimes are jurisdiction-specific by design. That is the point of them.
Common belief
The roof is only ten years old, so hurricane work would be wasted on it.
What is actually true
Age is not the variable. Deck attachment, deck sealing, edge detail, and vent products are the variables, and a ten-year-old roof installed to the minimum of an older adopted code may have none of them. Whether the work is worth doing now is mostly a question of whether the covering has to come off to reach the deck — which is a cost question, not an age question.
How it actually fails
- Corner-first peel
- Suction is highest at corners and edges, so the first courses to lift are almost always there. Once one course lifts, the one above it loses its lap and the failure runs inward along the edge.What you can see: From the ground, after a storm: a stepped or ragged line starting at a corner or rake rather than a hole in the middle of a slope. Creased-but-attached shingles along the edge count as damage even where nothing is missing.
- Water through the deck with the covering still on
- Wind-driven rain reaches the deck through lifted or unsealed courses and passes through sheathing joints or the gaps in a board deck. Nothing is visibly wrong from outside.What you can see: Ceiling stains appearing during the storm rather than after it, often near an exterior wall. The confirming sign is wet attic insulation with no identifiable hole above it — which is a contractor’s finding to report, not a reason to go up there yourself.
- Soffit loss into the attic
- Pressure on the underside of an overhang pushes vinyl or aluminium soffit panels out of their channels. FEMA records that water intrusion increases dramatically when the soffit material is missing.What you can see: Panels hanging, missing, or bowed under the eave. Water stains running down the inside face of an exterior wall rather than from the ceiling.
- Vent blow-off and vent water entry
- Ridge, off-ridge, gable, and turbine vents are surface-mounted devices in the highest-suction part of the roof. Some admit water under wind load; some leave entirely.What you can see: A ridge vent sitting proud of the ridge line, or a missing turbine — both readable from the ground. Daylight at a gable vent is a real sign, and it is one an inspector reports from inside.
- Garage door failure, then roof loss
- A large unreinforced opening fails, the interior pressurizes, and that internal pressure adds to the external suction already on the roof. FEMA lists roof loss as the example of what sudden interior pressurization can produce.What you can see: A bowed, buckled, or blown-in garage door. In a post-storm assessment this is a structural finding, not a cosmetic one.
- Sheathing loss
- Deck panels attached with too few fasteners, the wrong fasteners, staples, or nails that missed the framing. FEMA calls sheathing loss one of the most common structural failures in hurricanes and warns that losing one panel can lead to total building failure.What you can see: Bare framing visible from the ground, and sometimes daylight showing through a failed ceiling in the room below. This is the point at which a house is open, and a professional and the local building department are involved immediately.
Sources and further readingSection link
Understanding Roofing / Published
Scope and limitations
- It cannot tell you your design wind speed, your exposure category, or whether your address sits inside a windborne-debris region.
- Those are determinations for the code edition your jurisdiction adopted and for your building department.
- It cannot tell you what a specific roof will survive.
- Wind capacity is a calculation for a specific building with a specific geometry, height, attachment, and enclosure condition, made by a qualified design professional.
- It publishes no cost figure.
- Hurricane-resistance work is priced by deck condition, access, geometry, local labour, and which of several methods is specified, and there is no defensible national dataset that separates it from general re-roofing spend.
- The comparison table compares obligations and tradeoffs instead of dollars.
- It cannot tell you what your insurance covers, what a premium credit would be worth, or how a claim would be settled.
- The Alabama study describes portfolio outcomes in one storm in one state; it is not a statement about any policy.
- It cannot tell you whether an unvented assembly is permitted where you live, or whether it is right for your building.
- That is a design decision made against your adopted code, your climate zone, and your existing assembly.
- Most of what it describes — deck re-nailing, deck sealing, edge detail — can only be done with the covering off.
- It cannot tell you whether tearing off your current roof to reach the deck is worth it, because that depends on the covering's remaining life.
- The FEMA documents relied on here are the December 2010 editions.
- FEMA has published a second edition of P-804; this page has not read it, and nothing here should be treated as reflecting it.
Wind Retrofit Guide for Residential Buildings, FEMA P-804
U.S. Federal Emergency Management Agency / December 2010
That structural failures are not as common as other wind-related damage such as damage to the building envelope or wind-driven rain intrusion; the Basic, Intermediate, and Advanced Mitigation Packages and their cumulative structure; the two Basic options, with and without roof covering replacement, and that Option 1 is preferred because it ensures deck connections are checked and adequate underlayment installed; the deck refastening schedules distinguishing a four-foot roof edge zone from the field, and the illustration of those zones on gable and hip roofs; 8d ring-shank nails for structural wood panels and the instruction not to use clipped-head nails; the three secondary water barrier alternatives for shingle and metal roofs, including the ASTM D1970 membrane, the 4-inch self-adhering tape over sheathing joints, and the felt options, with Alternative 3 limited to design wind speeds of 110 mph or less; the bond-break underlayment over a full self-adhered membrane, specified to stop the covering bonding to the membrane and damaging the sheathing at the next replacement; the ASCE 7-05 exposure categories B, C, and D; the definition of the hurricane-prone region and the windborne-debris region; that a broken window or glass door may allow wind pressures to increase within the house, leading to structural damage; that systems protecting glazing from debris impacts are often not rated to reduce wind pressures on the opening they protect, a pressure rating on such a system typically being a rating against its own blow-off or excessive deflection; that an Intermediate-package retrofit protecting only the glazing of a garage door addresses windborne debris and not design pressures; that much of the damage in past high-wind events has been due to attic ventilation openings unable to resist high-wind forces; the stainless or hot-dip galvanised fastener recommendation within 3,000 feet of saltwater; that a shingle's durability rating indicated by warranty life is not an indicator of its ability to resist a particular wind speed; the Hurricane Ike house damaged at an estimated 93 mph, below the design wind speed; the Jefferson Parish house whose roof structure was destroyed at estimated wind speeds of only 50 mph; the pointer to the Applied Technology Council's wind speed website; and that the guide excludes manufactured homes.
FEMA technical guidance, not adopted law in any jurisdiction. Its wind speeds are keyed to ASCE 7-05 and ASCE 7-10 and to model code editions from 2009; the mapped speeds and the section numbering have changed since. fema.gov refused direct requests for this document, so the copy read was the federal PDF hosted by the National Institute of Building Sciences' Whole Building Design Guide. FEMA has published a second edition of P-804 that this page has not read; every attribution above is to the December 2010 first edition.
Home Builder's Guide to Coastal Construction, FEMA P-499 — Technical Fact Sheets 6.2, 7.1, 7.2, 7.3 and 7.5
U.S. Federal Emergency Management Agency / December 2010
Fact Sheet 7.1: that the highest uplift forces occur at roof corners, edges, and ridge lines; that sheathing loss is one of the most common structural failures in hurricanes; that loss of just one panel can lead to total building failure; that deformed-shank nails are required near ridges, gables, and eaves above 110 mph design wind speed; and that staples are not recommended. Fact Sheet 7.2: that its purpose is recommended practice for underlayment as an enhanced secondary water barrier; the three options listed in decreasing order of resistance to long-term weather exposure following loss of the roof covering; that Option 1 is advocated where design wind speed is 120 mph or greater and Option 3 only where it is 110 mph or less with modest population density; the ASCE 7-05 to ASCE 7-10 equivalences of 139 and 152 mph for Risk Category II; the specific materials and fastening for each option; and the statement that with Option 3 the underlayment has limited blow-off resistance and the option is intended where repairs are likely within several days of the covering blowing off. Fact Sheet 7.3: that wind-resistance ratings should be used to choose among shingles but not relied on for performance; that ASTM D3161 and UL 997 do not provide adequate information about wind performance; the UL 2390 Class D, G, and H ratings at 90, 120, and 150 mph; and the conditions — Exposure D, over 60 feet, Risk Category III or IV, abrupt topography — under which the manufacturer must be consulted. Fact Sheet 7.5: that hurricane winds can drive large amounts of water through attic ventilation openings, the accumulating water soaking insulation and leading to mould growth and in some cases ceiling collapse; the list of vent types observed to admit water or blow off; that water intrusion increases dramatically when soffit material is missing; that an unvented attic is the most conservative approach and a reliable way to prevent wind-driven rain entering the attic where permitted and appropriate; that unvented attics are controversial, that a conversion needs the advice of knowledgeable experts, and that one side effect may be voiding the roof covering warranty. Fact Sheet 6.2: that if the envelope is breached, sudden pressurization of the interior may result in major structural or non-structural damage such as roof loss and significant interior damage from wind-driven rain; that shutters will not eliminate wind-driven rain and should be assumed not to significantly decrease the wind-driven rain demand on the glazed assembly; and that garage doors are large unreinforced openings, commonly damaged, capable of allowing a building to be pressurized, and often labelled without a wind pressure rating.
FEMA technical guidance for coastal residential construction, not adopted law anywhere, and keyed to ASCE 7-05, ASCE 7-10, and 2009 model code editions. The fema.gov URL recorded above is the authoritative location but refuses automated requests. Every quotation used here was checked against the individual December 2010 fact sheet PDFs of the same federal publication as republished by municipal building departments — Fact Sheet 7.2 at townofedistobeach.com, Fact Sheet 7.3 at goosecreeksc.gov, Fact Sheet 6.2 at townofedistobeach.com — with Fact Sheet 7.1 checked against the identically worded Roof Sheathing Installation fact sheet at apps.floridadisaster.org and Fact Sheet 7.5 against the FEMA Hurricane Ike Recovery Advisory of the same title that it reprints.
IBHS research shows two critical ways to reduce risk of storm damage ahead of potentially active hurricane season
Insurance Institute for Business & Home Safety
That IBHS research estimates the equivalent of nine bathtubs of water can enter a home for every inch of rain that falls on a traditional roof deck where space between the boards is exposed; that there are four ways to cover those gaps and reduce the risk by as much as 95 percent; and that IBHS testing shows asphalt shingles, particularly as they age, can dislodge in winds as low as 60 mph, after which rain can pour into a house through gaps in the wood roof decking.
A research organisation's own news release summarising its own testing, not a peer-reviewed publication and not a code determination. The nine-bathtub estimate is stated for a board deck with exposed gaps, which is not every roof, and the 95 percent figure is stated as a reduction in the risk of water entering through those gaps, not as a reduction in total storm damage.
FORTIFIED Roof
FORTIFIED, a programme of the Insurance Institute for Business & Home Safety
That the FORTIFIED standard requires a sealed roof deck, ring-shank nails installed in an enhanced pattern with decreased spacing, a wider drip edge together with a fully adhered starter strip as a system, and attic vents that are wind and rain resistant.
A voluntary programme standard published by the organisation that owns it, not adopted code. Its requirements apply to buildings enrolled in and certified under the programme; they are not requirements anywhere by force of law, and this page does not treat them as such.
Roof 101
Insurance Institute for Business & Home Safety
That asphalt shingle tabs bond to the sealant strip of the shingle beneath and that this sealing is a critical part of installation; that sealing takes one to two weeks in optimal conditions and one to two months or more in poor conditions; that wind can lift unsealed shingles and water can seep underneath them before sealing occurs; and that the FORTIFIED approach combines a sealed roof deck with additional detail at the drip edge.
Consumer-facing educational material from a research organisation. It is not a manufacturer instruction for any specific product, and actual sealing behaviour depends on the product, the season, and the orientation of the slope.
Performance of IBHS FORTIFIED Home Construction in Hurricane Sally
Alabama Department of Insurance and the Center for Risk and Insurance Research, University of Alabama / 5 May 2025
The sample — 40,195 single-family owner-occupied wind policies from a state data call, of which 8,629 reported claims totalling $181,466,480, including 7,417 FORTIFIED houses; that across three analytical approaches FORTIFIED construction reduced loss frequency by 55 to 74 percent, loss severity by 14 to 40 percent, and loss ratio by 51 to 72 percent; that 46 percent of the claims in the sample were caused by trees falling on houses, which FORTIFIED is not designed to mitigate; that rainfall demonstrated a higher correlation with the damage ratio than either wind measure; that on its own rainfall is less likely to damage a house than wind speed or duration because rainfall cannot easily penetrate the envelope, but combined with wind it increases damage once the envelope begins to fail; that Alabama leads the nation with more than 50,000 FORTIFIED designations statewide; and that the Strengthen Alabama Homes grant programme accounts for more than 8,700 of those homes.
A retrospective insurance-claims analysis of one storm, in one state, in one year, on single-family owner-occupied policies south of I-10. It measures insurance outcomes rather than the physics of individual roofs, and its authors note they cannot test what caused the difference in performance between designation levels. It is also not disinterested: the report's own cover credits technical support from IBHS, which owns the FORTIFIED programme it evaluates, from Smart Home America, which promotes it, and from RenaissanceRe Risk Sciences. The data call and the analysis are the state regulator's and the university centre's, which is why it is cited here; the programme owner's involvement is why it is not treated as settled. It says nothing about what any particular policy covers, and it is not a basis for predicting a claim outcome.
Saffir-Simpson Hurricane Wind Scale
NOAA National Hurricane Center
That the Saffir-Simpson Hurricane Wind Scale is a 1 to 5 rating based only on a hurricane's maximum sustained wind speed; that it does not take into account other potentially deadly hazards such as storm surge, rainfall flooding, and tornadoes; and the category wind speed ranges, including Category 3 at 111 to 129 mph.
A meteorological intensity scale. It is not an engineering design value, it is not stated in the 3-second gust convention that wind design uses, and it describes the storm rather than the wind at any particular building.
NHC Glossary of Terms — Maximum Sustained Surface Wind
NOAA National Hurricane Center
That the standard measure of a tropical cyclone's intensity is the highest one-minute average wind, at an elevation of 10 metres with an unobstructed exposure, associated with that weather system at a particular point in time.
A definitions page. It establishes the averaging convention NOAA uses; it does not establish any relationship between that number and a structural design value.
Hurricane Research Division FAQ
NOAA Atlantic Oceanographic and Meteorological Laboratory
That maximum sustained wind is determined as winds lasting for an average of at least one minute at about 33 feet (10 metres), and that gusts are classified as a 3 to 5 second burst of wind higher than the maximum sustained wind.
A public-education FAQ from a NOAA research laboratory. It describes meteorological convention, not the 3-second gust convention as it is defined for structural design in ASCE 7, which this page does not quote directly.
Hurricane Preparedness — Hazards
NOAA National Hurricane Center
That storm surge and large waves pose the greatest threat to life and property along the coast; that hurricane-force winds of 74 mph or more can destroy buildings and mobile homes and can stay above hurricane strength well inland, with Hurricane Charley in 2004 given as the example of inland gusts exceeding 100 mph across central Florida; that tropical cyclones often produce widespread torrential rains in excess of 6 inches; and that flooding is the major threat from tropical cyclones for people living inland.
Public preparedness guidance. It describes hazards in general terms and is not a source for building performance or for any determination about a specific site.
Tropical Cyclone Climatology
NOAA National Hurricane Center
That the Atlantic hurricane season runs from June 1 to November 30; that an average season over the 1991–2020 base period includes 14 named storms, 7 hurricanes, and 3 major hurricanes; and that the peak of the season is 10 September, with most activity between mid-August and mid-October.
Basin-wide climatology. It says nothing about the probability of a storm affecting any particular location in any particular year.
Florida Statutes § 553.842 — Product evaluation and approval (2025)
The Florida Senate, publishing the Florida Statutes — adopted law in Florida only / 2025 Florida Statutes; the section's history line records its last amendment as s. 6, ch. 2021-201
That statewide approval precludes local jurisdictions from requiring further testing, evaluation, or submission of other evidence as a condition of using the product so long as it is used consistent with the conditions of its approval; that roofing is among the categories the commission must approve by one of the statutory methods; that a product may not be advertised, sold, offered, provided, distributed, or marketed as hurricane, windstorm, or impact protection from wind-borne debris unless it is approved under this section or s. 553.8425, and that doing so exposes the seller to the Florida Deceptive and Unfair Trade Practices Act; and that a building official may deny local application of a statewide-approved product by written report concluding the application is inconsistent with the approval.
Adopted law in Florida and nowhere else, in the 2025 compilation published by the Florida Senate. It is not evidence about any other state, most of which have no product approval regime at all. Confirm the current text and any subsequent amendment with the Florida Building Commission and the local building official.
Notice of Acceptance 22-0816.05, BLACKKNIGHT underlayment (Microfiber Corp Private Limited)
Miami-Dade County, Department of Regulatory and Economic Resources, Product Control Section / Approved 8 September 2022; expires 8 September 2027
The standing language of a Notice of Acceptance: that it is issued to be used in Miami-Dade County and other areas where allowed by the authority having jurisdiction; that it is not valid after the stated expiration date; that renewal is considered only on application and where there has been no change in the applicable building code negatively affecting the product's performance; that termination follows the expiration date or any revision or change in the materials, use, or manufacture; that misuse of the NOA as an endorsement for sales or advertising automatically terminates it; that a copy must be available for inspection at the job site; and that the approval names specific installation requirements — here 4-inch head laps, 6-inch end laps, and corrosion-resistant tin-caps with 12-gauge annular ring-shank nails at stated spacings.
One approval document, for one underlayment product, from one jurisdiction, with an expiration date in 2027. It is cited here only as evidence of what an approval document is and what it says about its own limits. It is not a recommendation of the product, and nothing in it applies to any other product or assembly.
Fall Protection in Residential Construction
U.S. Occupational Safety and Health Administration
That falls are the leading cause of death for workers engaged in residential construction, and that workers engaged in residential construction six feet or more above lower levels must be protected by conventional fall protection.
Occupational-safety guidance for employers and workers. It is not homeowner guidance; that trained workers use fall protection is a reason for an untrained reader to stay off a roof, not a procedure to copy.