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1. The design wind speed for the area is 130 mph or greater regardless of tree covering or the surroundings.
2. The design wind speed for the area is 120 mph or greater and you live in an area with moderate tree covering.
3. The home is in a neighborhood with few trees and the design wind speed for the area is 110 mph or greater.
4. The vulnerability goes up significantly if the home has a tile roof or if one or more of the neighbors has a tile roof, a flat roof with gravel ballast or, old shingles that are starting to curl.
If the home does not have hurricane clips or straps holding the roof structure to the walls, window and door protection may make the critical difference between losing the roof and keeping it on. If a large window or door is broken open on the wall facing into the wind, the overall uplift forces that are trying to lift the roof off the house may be doubled. In other words, if it is likely that the roof of the home would lift off during a Category 2 hurricane if a large window broke open on the windward side of the house, it might take a Category 3 or Category 4 storm to lift the roof off if all of the windows and doors are kept in tact.
Installing impact rated shutters over windows and doors can protect them from the impacts of windborne debris and can keep wind pressures from building up in the house. However, shutters may not keep the doors and windows from failing due to wind pressure if they are weak or poorly anchored to the walls of the house.
The test standards for water intrusion are set at 15% of the design pressure for the window or door. If the window or door in the home has a design pressure rating of 50 pounds per square foot of wind pressure (a pressure you might expect from a storm with wind gusts of 140 mph) it only has to resist a pressure of 7.5 pounds per square foot without leaking (a pressure that occurs when wind gusts reach 55 mph) to pass the water intrusion test standard. Keeping water from being driven against and building up on windows and doors is one way to minimize the water intrusion during a hurricane.
• The strength of the door including its ability to resist windborne debris impacts.
• The anchorage of the door to the door frame in its closed and locked position including its ability to remain closed.
• The anchorage of the door frame to the wall structure.
• Reducing the potential for water intrusion.
Hinged doors are usually large compared to a piece of glass in a window. So if a door gets broken open by wind, unless it is shuttered with a non-porous system, it will almost always result in pressurization of the interior of the home.
Strength of the Door
If the door opens to the outside, the door and framing are metal and there is no glass in the door, the door panel itself has a good chance of resisting wind pressures and hurricane debris. Some solid wood doors will also provide good protection from wind pressure and debris impacts. In some cases, we have found stickers on the edge of the door where the hinges are mounted that indicate the design pressure and impact rating for the door.
Doors may not be as strong as they seem. Even doors with metal surfaces/skins frequently have a wood framework around the edges and possibly a foam core. While the metal may help keep windborne debris from penetrating the face of the door, it is not uncommon to have the edge of the door split at the latch and the metal buckle around the latch, under either wind pressure or the impact of debris. While a shutter system will typically protect the door from the impact of windborne debris, most allow enough air leakage around the edges of the shutter or through corrugations, even if they are capped, so that the door can become fully loaded with the wind pressure from the storm. In Hurricane Charley, a number of homeowners had their exterior entry doors burst open even though they were shuttered with porous shutters.
Doors with metal skins often perform better than wood doors. However, the latching and framing are critical to total system performance. The best way to keep the exterior entry doors closed during a storm is to have pressure rated doors that are well anchored to the frame with adequate locks to handle the wind pressure. Having a door that is also impact rated will mean that you do not need to shutter the door to protect it from windborne debris.
You can shutter doors with a code approved pressure and impact rated shutter system, but you must keep at least one door operable from inside the house to provide emergency escape to the outside. This can be done by using an accordion shutter system that can be operated from both inside and outside the house. Also consider replacing at least one door with one that is code approved for wind pressures appropriate for the area and debris impact tested and approved.
Sliding Glass Doors
Sliding glass doors (patio doors), while wonderful for views and openness, do expose houses to risk. The problem is that unless sliding glass doors were specifically designed for high wind, they typically are not very resistant to being pushed into or out of a house by wind pressure. When that happens wind driven rain will come in and it is possible that doors and windows on the other side of the house will get blown out. When this happens, wind and water can blow through the house, and damage can be extensive.
Newer sliding glass doors use tempered glass, which is about twice as strong as regular window glass. (If it is tempered glass, a label indicating this will be etched in one of the corners.) However, even if a door has tempered glass it is still very vulnerable to getting pushed out of its tracks and head piece or being shattered by large debris. The tracks and head pieces on non-wind rated doors have not been designed to hold the doors in place in strong winds.
Shuttering the doors is one of the most effective ways to protect them from flying debris, and helps reduce water intrusion. Using a non-porous shutter system will also help prevent the house from getting pressurized if a sliding glass door fails during a hurricane. However, most shutter systems, even those that are considered non-porous, allow pressure to build up behind the shutter on the sliding glass door. That pressure can cause the door to pop out or the glass to break. In some cases, the tracks for the doors may not be well attached to the walls of the house.
There are many of shutter products available for protecting sliding glass doors. If the doors open onto a porch or lanai, installing code approved impact resistant screen products or accordion shutters around the perimeter may be the most cost effective ways to protect all the openings to that area from flying debris and also reduce water intrusion around the doors.
Failure of the garage door allows the full fury of the hurricane to act on interior walls, doors, ceiling or roof that form the barriers between the inside of the garage and the rest of the house. This frequently leads to failure of these surfaces and can lead to significant loss of roof sheathing and roof integrity.
Water intrusion around the perimeter of a garage door is not usually a big problem unless you have things that can be damaged by water sitting directly on the floor. Most garage floors are sloped towards the door so that water that blows in around the door will tend to drain out of the garage. However in a hurricane, winds may blow water into the garage for some time so it is probably prudent to raise vulnerable contents off the floor and away from the door.
Backing the car against the door provides little additional bracing. It may help brace the bottom panel from positive (inward acting) pressure; but, it will do nothing to help with negative (outward acting) pressures. It just puts the car closer to possible debris impact damage.
Protecting the Garage Door Opening:
One of the simplest solutions is to replace the door and its tracks with a door that is code approved for both wind pressure and impact protection. When selecting a door there are two primary considerations. One is to be sure the door is rated for the correct wind pressure for the area in which the house is located. The other is to select a door that is also debris rated.
Another solution is to protect the garage door with a shutter or screen product that is rated for both wind pressure and debris impact. Storm panels are an easy way to protect a garage door because they are effective and are relatively easy to deploy. If the door is pressure rated as required by the current building code, then storm panels may be the best choice. On the other hand if the door is deteriorated and is or will be in need of replacement then replacing the door will be most cost effective in the long term.
Impact rated residential doors and windows or the protective systems for doors and windows are tested to determine their ability to resist the impact of large wind borne debris (missiles) by shooting 2x4s of specified lengths and weights against them at specific speeds. Several different groups have developed engineering standards that establish missile sizes, test methods and acceptance criteria for the tests. For houses, the typical large missile test consists of a 9-pound 2x4 piece of lumber impacting the shutter or product end on at 34 mph.
The referenced standards for opening protection in hurricane windborne debris area are:
Florida Building Code: TAS 201 Large and Small Missile Test Standards, TAS 202 Uniform Structural Load Standards, and TAS 203 Uniform Cyclic Pressure Test Standards. These are the Test Standards required for a Miami-Dade Product Approval. A product with a NOA (Notice of Acceptance) is approved for use in Miami-Dade and Broward counties if it meets the requirements of these test standards.
ASTM E 1886 Standard Test Method for Performance of Exterior Windows, Curtain Walls, Doors, and Storm Shutters Impacted by Missile(s) and Exposed to Cyclic Pressure Differentials, and, ASTM E 1996 Standard Specification for Performance of Exterior Windows, Curtain Walls, Doors and Storm Shutters Impacted by Windborne Debris in Hurricanes. These are the Test Standards required for Product Approval in the rest of Florida and in International Building Code for use in Windborne Debris Regions for the US, Hawaii, and Caribbean Islands.
SBCCI Test Standard for Determining Impact Resistance From Windborne Debris SSTD-12-97 (Note: This Test Standard will no longer be accepted.)
There is a fundamental difference in the acceptance criteria for impact rated windows and doors and storm shutter performance between the Miami-Dade County Standard (Florida Building Code High Velocity Hurricane Zone test standard – HVHZ) and those of other organizations. The Miami-Dade County Standard does not allow the test missile (9-pound 2x4 at 34 mph) to penetrate the unit or protective system and does not allow it to break the glass behind the protective system. The other standards allow the test missile to penetrate the protective system provided the opening does not increase in size as it is subjected to wind pressures and so long as after all the testing is completed, the hole is small enough so that a 3-inch diameter sphere will not pass through the hole. The focus of these alternative test standards is to prevent pressurization of the home and reduce the chances of additional pressure related failures of the home. The Miami-Dade County Standard targets protection of the window behind the protective system. Consequently, a protective system that meets the Miami-Dade Standard and is installed according to their product approval requirements may provide a higher level of protection. An exception is impact resistant glass, where all of the standards including the Miami-Dade County Standard allow the glass to be broken, but not penetrated.
Accordion Shutters (Porous and Non-porous)
The system operates from side to side and is permanently attached to the exterior. It can be operated from the outside or inside of the house with in-swing or sliding glass doors. It can also be operated from inside if the window is a slider, single or double hung. Operation from the inside is not possible with out-swing doors, casement windows, some jalousie windows, or fixed windows. Accordion shutters, like screen protection systems are also very effective at closing off large areas like patios or lanais.
Roll Shutters (Porous and Non-porous)
These shutters can be operated from inside, outside, remote control, or even automatically on any type window or door.
Colonial Hinged Shutters (Porous and Non-porous)
This popular style works well in historical districts or where a decorative feature is desired. The operation is generally from the outside only and requires installation of additional hardware or storm bars to keep them closed in a hurricane. The technology of shutters is evolving. A few inside locking systems are beginning to emerge on the market. Many of these systems are non-porous because they use a solid backing behind the slats.
Bahama Shutters (Porous and Non-porous)
Like the Colonial hinged shutters, these systems add a decorative accent. In addition they shade the windows, like an awning, reducing heat gain through the glazing system. Some systems are designed to be operated from inside but the majority are designed for operation from the outside. Most also have additional hardware that must be added to secure the shutter for a hurricane. Most of these systems are Non-Porous systems, the system in this picture is only impact resistant when the louvers are covered by a .040 aluminum sheet on the back, and this blocks all visibility through the slats.
Windows and Doors
Introduction
Protecting windows and doors (including sliding glass doors and garage doors) from windborne debris is an important part of protecting the home, the belongings, and the roof in a hurricane. A home is particularly vulnerable to having unprotected windows being broken by windborne debris if:1. The design wind speed for the area is 130 mph or greater regardless of tree covering or the surroundings.
2. The design wind speed for the area is 120 mph or greater and you live in an area with moderate tree covering.
3. The home is in a neighborhood with few trees and the design wind speed for the area is 110 mph or greater.
4. The vulnerability goes up significantly if the home has a tile roof or if one or more of the neighbors has a tile roof, a flat roof with gravel ballast or, old shingles that are starting to curl.
If the home does not have hurricane clips or straps holding the roof structure to the walls, window and door protection may make the critical difference between losing the roof and keeping it on. If a large window or door is broken open on the wall facing into the wind, the overall uplift forces that are trying to lift the roof off the house may be doubled. In other words, if it is likely that the roof of the home would lift off during a Category 2 hurricane if a large window broke open on the windward side of the house, it might take a Category 3 or Category 4 storm to lift the roof off if all of the windows and doors are kept in tact.
Installing impact rated shutters over windows and doors can protect them from the impacts of windborne debris and can keep wind pressures from building up in the house. However, shutters may not keep the doors and windows from failing due to wind pressure if they are weak or poorly anchored to the walls of the house.
The test standards for water intrusion are set at 15% of the design pressure for the window or door. If the window or door in the home has a design pressure rating of 50 pounds per square foot of wind pressure (a pressure you might expect from a storm with wind gusts of 140 mph) it only has to resist a pressure of 7.5 pounds per square foot without leaking (a pressure that occurs when wind gusts reach 55 mph) to pass the water intrusion test standard. Keeping water from being driven against and building up on windows and doors is one way to minimize the water intrusion during a hurricane.
Entry Doors
There are four things to consider for exterior entry doors and how to make them less likely to be damaged or to leak during a hurricane. They are:• The strength of the door including its ability to resist windborne debris impacts.
• The anchorage of the door to the door frame in its closed and locked position including its ability to remain closed.
• The anchorage of the door frame to the wall structure.
• Reducing the potential for water intrusion.
Hinged doors are usually large compared to a piece of glass in a window. So if a door gets broken open by wind, unless it is shuttered with a non-porous system, it will almost always result in pressurization of the interior of the home.
Strength of the Door
If the door opens to the outside, the door and framing are metal and there is no glass in the door, the door panel itself has a good chance of resisting wind pressures and hurricane debris. Some solid wood doors will also provide good protection from wind pressure and debris impacts. In some cases, we have found stickers on the edge of the door where the hinges are mounted that indicate the design pressure and impact rating for the door.
Wood panel door before impact test.
Wood panel door after impact with 2x4 missile.
Doors with metal skins often perform better than wood doors. However, the latching and framing are critical to total system performance. The best way to keep the exterior entry doors closed during a storm is to have pressure rated doors that are well anchored to the frame with adequate locks to handle the wind pressure. Having a door that is also impact rated will mean that you do not need to shutter the door to protect it from windborne debris.
You can shutter doors with a code approved pressure and impact rated shutter system, but you must keep at least one door operable from inside the house to provide emergency escape to the outside. This can be done by using an accordion shutter system that can be operated from both inside and outside the house. Also consider replacing at least one door with one that is code approved for wind pressures appropriate for the area and debris impact tested and approved.
Sliding Glass Doors
Sliding glass doors (patio doors), while wonderful for views and openness, do expose houses to risk. The problem is that unless sliding glass doors were specifically designed for high wind, they typically are not very resistant to being pushed into or out of a house by wind pressure. When that happens wind driven rain will come in and it is possible that doors and windows on the other side of the house will get blown out. When this happens, wind and water can blow through the house, and damage can be extensive.
Newer sliding glass doors use tempered glass, which is about twice as strong as regular window glass. (If it is tempered glass, a label indicating this will be etched in one of the corners.) However, even if a door has tempered glass it is still very vulnerable to getting pushed out of its tracks and head piece or being shattered by large debris. The tracks and head pieces on non-wind rated doors have not been designed to hold the doors in place in strong winds.
Failure of the French doors at the front of this house resulted in the sliding glass doors being blown out of their tracks. Note that one of the tempered glass panels did not break.
There are many of shutter products available for protecting sliding glass doors. If the doors open onto a porch or lanai, installing code approved impact resistant screen products or accordion shutters around the perimeter may be the most cost effective ways to protect all the openings to that area from flying debris and also reduce water intrusion around the doors.
A screen product protecting an entire porch area keeps water away from doors.
Garage Doors
Because garage doors are so big, usually the single biggest opening on the house, and because most old doors are so weak, the survival of the garage door is very important to the survival of the house. Experience has shown in older houses that when garage doors fail in hurricane winds, serious additional damage follows. Older garage doors and new ones that are not pressure rated are highly susceptible to wind damage, including buckling, twisting off the tracks and failure due to impact from windborne debris. Doors can be pushed in by winds blowing onto the door or pulled out as winds whip around the corner of the house where the door is located.
Garage door pushed in by the wind.
Garage door pulled out by the wind.
The failure of this garage door probably contributed to the loss of roof sheathing.
Backing the car against the door provides little additional bracing. It may help brace the bottom panel from positive (inward acting) pressure; but, it will do nothing to help with negative (outward acting) pressures. It just puts the car closer to possible debris impact damage.
Garage door blown in on top of car.
One of the simplest solutions is to replace the door and its tracks with a door that is code approved for both wind pressure and impact protection. When selecting a door there are two primary considerations. One is to be sure the door is rated for the correct wind pressure for the area in which the house is located. The other is to select a door that is also debris rated.
Another solution is to protect the garage door with a shutter or screen product that is rated for both wind pressure and debris impact. Storm panels are an easy way to protect a garage door because they are effective and are relatively easy to deploy. If the door is pressure rated as required by the current building code, then storm panels may be the best choice. On the other hand if the door is deteriorated and is or will be in need of replacement then replacing the door will be most cost effective in the long term.
Windows
Shutter and awning systems have been in use for over 200 years. They can be designed to provide protection from wind and water, increase security, block solar heat, increase privacy, and some are designed purely for decorative use. Here we focus on their impact resistance and the test standards that have been developed in the last 20 years to assess their ability to provide protection from windborne debris. While shutter systems may also provide some additional protection from water damage, this is not their primary purpose nor are they tested in any way to determine a specific level of water penetration protection. Impact resistant shutter systems are designed to protect the openings in a house from the type of failure that can lead to a large increase in internal pressure in the house.Impact rated residential doors and windows or the protective systems for doors and windows are tested to determine their ability to resist the impact of large wind borne debris (missiles) by shooting 2x4s of specified lengths and weights against them at specific speeds. Several different groups have developed engineering standards that establish missile sizes, test methods and acceptance criteria for the tests. For houses, the typical large missile test consists of a 9-pound 2x4 piece of lumber impacting the shutter or product end on at 34 mph.
The referenced standards for opening protection in hurricane windborne debris area are:
Florida Building Code: TAS 201 Large and Small Missile Test Standards, TAS 202 Uniform Structural Load Standards, and TAS 203 Uniform Cyclic Pressure Test Standards. These are the Test Standards required for a Miami-Dade Product Approval. A product with a NOA (Notice of Acceptance) is approved for use in Miami-Dade and Broward counties if it meets the requirements of these test standards.
ASTM E 1886 Standard Test Method for Performance of Exterior Windows, Curtain Walls, Doors, and Storm Shutters Impacted by Missile(s) and Exposed to Cyclic Pressure Differentials, and, ASTM E 1996 Standard Specification for Performance of Exterior Windows, Curtain Walls, Doors and Storm Shutters Impacted by Windborne Debris in Hurricanes. These are the Test Standards required for Product Approval in the rest of Florida and in International Building Code for use in Windborne Debris Regions for the US, Hawaii, and Caribbean Islands.
SBCCI Test Standard for Determining Impact Resistance From Windborne Debris SSTD-12-97 (Note: This Test Standard will no longer be accepted.)
There is a fundamental difference in the acceptance criteria for impact rated windows and doors and storm shutter performance between the Miami-Dade County Standard (Florida Building Code High Velocity Hurricane Zone test standard – HVHZ) and those of other organizations. The Miami-Dade County Standard does not allow the test missile (9-pound 2x4 at 34 mph) to penetrate the unit or protective system and does not allow it to break the glass behind the protective system. The other standards allow the test missile to penetrate the protective system provided the opening does not increase in size as it is subjected to wind pressures and so long as after all the testing is completed, the hole is small enough so that a 3-inch diameter sphere will not pass through the hole. The focus of these alternative test standards is to prevent pressurization of the home and reduce the chances of additional pressure related failures of the home. The Miami-Dade County Standard targets protection of the window behind the protective system. Consequently, a protective system that meets the Miami-Dade Standard and is installed according to their product approval requirements may provide a higher level of protection. An exception is impact resistant glass, where all of the standards including the Miami-Dade County Standard allow the glass to be broken, but not penetrated.
Accordion Shutters (Porous and Non-porous)
The system operates from side to side and is permanently attached to the exterior. It can be operated from the outside or inside of the house with in-swing or sliding glass doors. It can also be operated from inside if the window is a slider, single or double hung. Operation from the inside is not possible with out-swing doors, casement windows, some jalousie windows, or fixed windows. Accordion shutters, like screen protection systems are also very effective at closing off large areas like patios or lanais.
Accordion shutters open
Shutters closed
These shutters can be operated from inside, outside, remote control, or even automatically on any type window or door.
Hidden mount Roll completely hide the hood when built into the eave.
Typical installation of Roll Shutters.
Roll shutters are typically mounted under the eaves with the hoods exposed. Left: When the span reaches a certain width, additional vertical reinforcing bars called storm bars are used to keep the slats from coming out of the tracks under positive or negative pressure.
Fabric Roll Shutters
This popular style works well in historical districts or where a decorative feature is desired. The operation is generally from the outside only and requires installation of additional hardware or storm bars to keep them closed in a hurricane. The technology of shutters is evolving. A few inside locking systems are beginning to emerge on the market. Many of these systems are non-porous because they use a solid backing behind the slats.
These shutters add an attractive accent to the front of the home. Less expensive shutter systems were used elsewhere to reduce the overall cost of the job. One drawback is that the upper shutters must be operated from the outside which requires using a ladder to install the hurricane hardware.
Colonial Hinged shutters can also be customized for a historical look; these are integral arch top shutters to cover the large arch top windows.
Like the Colonial hinged shutters, these systems add a decorative accent. In addition they shade the windows, like an awning, reducing heat gain through the glazing system. Some systems are designed to be operated from inside but the majority are designed for operation from the outside. Most also have additional hardware that must be added to secure the shutter for a hurricane. Most of these systems are Non-Porous systems, the system in this picture is only impact resistant when the louvers are covered by a .040 aluminum sheet on the back, and this blocks all visibility through the slats.
The picture shows a decorative Bahama awning shutter system. Impact resistant shutters were not required in this area until 2002. The remaining openings were covered with metal panels to reduce the overall cost. Since those openings could be accessed from the decks the panels did not have to be installed from a ladder.
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