Hurricane and High Wind Zones

In high wind- and hurricane-prone areas, here is a summary of steps that can be taken to improve the storm resistance of exterior doors, based on the detailed information provided below and in the cited documents by FEMA and others:

• All exterior doors on homes in hurricane-prone areas should be pressure and impact rated or protected by a system that is pressure and impact rated, according to the Insurance Institute for Business & Home Safety (IBHS 2019). See the Solution Center guide Exterior Doors Are Insulated, Impact Rated, and Fire Rated for more information.
• Doors should have flashing and weatherstripping, be properly air-sealed, and be set in pan flashings designed to resist the entry of wind and wind-driven rain.
• For increased disaster resistance in coastal and high wind areas, install exterior doors to swing outward rather than inward. Weather stripping should be installed on the interior side of the door to minimize decay.
• Consider designing the home’s entry with a vestibule or double-doored entry. 
• Install water-resistant flooring at all entryways.
• Doors, door framing, and door hardware should be made of water-resistant, corrosion-resistant materials.
• Exterior doors should meet U-factor requirements for the home's climate zone, as required by local building codes. Please see the Compliance Tab for more information.
• See FEMA P-499 Technical Fact Sheet No. 6.1: Window and Door Installation for best-practice approaches that can be taken to reduce water infiltration. Pan flashing, weather stripping, and threshold seals are discussed. The Solution Center guide Windows and Doors are Fully Flashed and the Tech Note: Window and Door Flashing: Code Requirements and Best Practices by Home Innovation Research Labs provide additional detailed instructions for installing window and door flashing.

In all areas where buildings are constructed, windows and doors tend to be more vulnerable to damage than other portions of a building's envelope. In coastal areas where high winds, windborne debris, and wind-driven rain are common and often intense their vulnerabilities are more pronounced (FEMA P-762 2009). Air leaks around doors can allow wind entry during high-wind events, contributing to internal pressure changes that can contribute to building failures (FEMA P-762 2009). Flashing is required by the 2021 International Residential Code (IRC) Section R703.4 to prevent moisture from entering the wall system.

Water leakage around windows and doors is also quite common but because the effects of water leakage are often subtle, the full effects of water leakage are often not readily apparent. Water-resistant siding materials like vinyl and veneer can hide moisture damage in the sheathing caused by rainwater entry for years. Leakage or water entry due to inadequate or improperly installed flashing, weatherstripping, or weather-resistant barriers can allow water to enter a building’s interior even when the structure of the window or door remains intact. Water intrusion can cause rot and fastener corrosion that can weaken the window or door frame or the wall framing itself. Leakage can also cause damage to interior finishes and facilitate mold growth (FEMA P-762 2009).

Windows and doors can fail if they are not strong enough to resist wind pressures from a high-wind event or if forces exerted on the doors or windows exceed the strength of their anchorage. When strength is inadequate, the window or door’s glazing or frames fail; when anchorage is inadequate, the entire door or window unit can be torn from its mounting. As wind speeds increase due to storm strength in Category 2 or weak Category 3 levels, failures of these elements become more frequent. Wind pressure increases resulting from the failure of windows and doors can significantly increase (in some cases doubling) the wind forces working to blow the roof off or blow out exterior walls.

The FEMA P-762 Local Officials Guide to Coastal Construction provides the following guidance on window and door leakage (excerpted): 

Hurricanes and coastal storms can pose significant problems from water-infiltration due to wind-driven rain. Leakage can occur between the door or window and their frames and between the door/window frames and the walls onto which they are mounted. Coastal storms such as tropical storms and hurricanes generate winds that may approach or exceed the wind speeds observed during design wind events. As such, these winds generate high-wind pressures on the outsides of the buildings, exploiting any vulnerability around doors and windows and allowing water to enter buildings.

Further, leakage rates typically increase with greater wind speeds. While the amount of water entry will typically be much less from leakage around windows and doors than the water entry that can result from a breach in the building envelope, actions can and should be taken to help reduce leakage around doors and windows. These actions are often above code or best-practices approaches.

Code Requirements for Window and Door Leakage 

The IRC and the International Building Code (IBC) both specify that windows, sliding doors, and exterior doors meet testing requirements specified in AAMA/ WDMA/CSA 101/I.S.2/A440 and/or ASTM E330.

Reducing Window and Door Leakage 

FEMA P-499 Technical Fact Sheet No. 6.1: Window and Door Installation, provides some best-practice approaches that can be taken to reduce water infiltration. Pan flashing (i.e., flashing under windowsills), weatherstripping, and threshold seals are discussed. Other actions can be taken to reduce the potential for water entry. These include:

• Vestibules. Designing a vestibule, or double-doored entry, to protect a door entry is one method of managing water infiltration problems. Through this approach, both the inner and outer doors can be equipped with weatherstripping, and the vestibule itself can be designed to tolerate water. For example, water-resistant finishes (e.g., concrete or tile) can be specified, and the floor can be equipped with a drain. As a result, a secondary layer of protection is provided for the primary entrance (via the vestibule and vestibule door).
• Door swing. Out-swinging doors offer an advantage compared to in-swinging door assemblies. With out-swinging door assemblies, the weatherstripping is located on the interior side of the door, where it is less susceptible to degradation than the exposed weatherstripping on in-swinging door assemblies. Also, some interlocking weatherstripping products are available for out-swinging door assemblies that provide better performance than those used on in-swinging door assemblies.
• Finish selection. One design approach to deal with leakage is to avoid running carpet (or other finishes that can be damaged by water) entirely to the edge of walls that contain a large amount of glazing. Instead, a strip of water-resistant material (such as tile) could be specified along the wall so if light to moderate leakage occurs, the potential for damage to interior finishes and contents is greatly reduced.

Code Requirements for Strength and Anchorage 

The IRC and the IBC both specify that windows, sliding doors, and exterior doors meet testing requirements for strength and anchorage to resist wind pressures

Pests

In areas where severe termite or insect infestation problems exist (see Figure 1, a termite infestation map), wood frames, shims, and bucks should either be pressure-treated or should be constructed with wood that is naturally insect- and rot-resistant. Since some pressure treatment increases the moisture content of framing, the use of material that is kiln dried after treatment is duggested to control shrinkage. Metal doors are recommended. PVC trim should be used (FEMA P-762 2009). 

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Termite Infestation Probability Map, Adapted from the 2021 International Residential Code (IRC), Figure R301.2(7)

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• Use solid-core doors where possible. Solid-core doors are more durable and do not have hidden recessed areas or cavities that could harbor pests.
• In areas of high rodent pressure, install metal doors or fit external doors with 26-gauge sheet metal kick plates 12 inches tall and mounted no more than 1/4 inch from the bottom of the door.
• Ensure that doors fit tightly with less than ¼ inch between the bottom of the door and the threshold. Use tight-fitting door sweeps if gaps are larger than 1/4 inch.
• Install a door sweep – automatic door sweeps or bristle sweeps are preferable to rubber or plastic sweeps. Install door sweeps that touch the ground and go the entire length of the bottom of the door. If properly installed, the sweep will brush the ground, but not hold the door open (a fire hazard). In areas prone to rodent infestation, do not use vinyl sweeps. 
• Equip exterior doors with self-closing devices.
• Install screen doors with a heavy kick plate and durable frames to prevent warping and ensure a good seal from the outdoors.
• Use weatherstripping on all exterior doors.
• Install screens and weatherstripping on all operable exterior windows.
• Install head flashing, side flashing, and sill pan flashing around all windows and doors.
• Avoid planting shrubs or installing trellises near doorways.