Mitigation Assessment Team Report
Hurricane Charley in Florida
Observations, Recommendations, and Technical Guidance
FEMA 488
April 2005

Chapter 8. Recommendations

The recommendations in this report are based solely on the observations and 
conclusions of the MAT, and are intended to assist the State of Florida, local 
communities, businesses, and individuals in the reconstruction process and to 
help reduce damage and impact from future natural events similar to Hurricane 
Charley. The general recommendations presented in Section 8.1 relate to policies 
and education/outreach that are needed to ensure that designers, contractors, 
and building officials understand the requirements for disaster resistance 
construction in hurricane-prone regions. Proposed changes to codes and statutes 
are presented in Section 8.2.

In addition to these general and code related recommendations, specific 
recommendations for improving the performance of the building structural system 
and envelope, as well as the protection of critical and essential facilities (to 
prevent loss of function) are provided later in this chapter. Implementing these 
specific recommendations in combination with the general recommendations of 
Section 8.1 and the code and statute recommendations of Section 8.2 would 
significantly improve the ability of the built environment to resist damage from 
hurricane force winds. Recommendations specific to building structural and  
envelope issues, critical and essential facilities, and education and outreach 
have also been provided. 

8.1	General Recommendations

As the people of Florida rebuild their lives, homes, and businesses, there are a 
number of ways they can avoid the effects of future natural hazards, including:

--Design and construct facilities to at least the minimum design requirements in 
the 2001 FBC and the 2004 FBC (after it becomes effective in the summer of 2005)

--When renovating or remodeling for  a building's structural or envelope 
improvements (both residential and commercial), involve a structural 
engineer/design professional/licensed contractor in the design and planning 

--Assure code compliance through increased enforcement of construction 
inspection requirements such as the Florida Threshold Inspection Law or the IBC 
Special Inspections Provisions

--Perform follow-up inspections after a hurricane to look for interior moisture 
that may affect the structure or building envelope

--Use the necessity of roof repairs to damaged buildings as an opportunity to 
significantly increase the future wind resistance of the structure

The following recommendations are specifically provided for state and Federal 
government agencies:

--The government should place a high priority on and allocate resources to 
hardening, providing backup power and data storage to NOAA's/NWSs surface 
weather monitoring systems, including ASOSs located in hurricane-prone regions. 
Continued support is also needed for maintenance, expansion, and deployment of 
stand-alone unmanned surface observation systems that can be safely and reliably 
placed in advance of a landfalling hurricane. Support should be provided for the 
real-time communication of data from all these systems to forecasters and wind 
field modeling efforts.

--The government should place a high priority on continuing to fund the 
development of several different tools for estimating and mapping wind fields 
associated with hurricanes and for making these products available to interested 
parties as quickly as possible after a hurricane strikes.

8.2 	Proposed Changes to Codes and Statutes

Buildings constructed in accordance with 2001 FBC (and those that had been 
mitigated to resist high-wind loads) were observed to perform substantially 
better than typical buildings constructed to earlier codes, but their 
performance was not without exception. The study of buildings and their 
interaction with high winds associated with hurricanes is a continuous process 
and much has been learned since the current FBC was developed and adopted. 
Incorporating these recommendations into the next available code cycle is key to 
setting the new standard in hurricane-resistant construction in Florida and all 
hurricane-prone regions. 

The following is a list of recommendations specific to the codes and statutes 
currently adopted and being enforced in the State of Florida. If these 
recommendations are not codified by the state in response to the hurricanes of 
2004, the design changes recommended herein should be considered best 
practices in hurricane-resistant construction and incorporated in all new 
construction and mitigation projects to the maximum extent possible. The 
preliminary conclusions and recommendations from this MAT report were presented 
to the Florida Building Commission and to FL DCA in December 2004 at the 
Hurricanes Charley, Frances, Ivan, and Jeanne Workshop sponsored by the 
Commission and IBHS.

In response to Hurricane Season 2004, the Florida Building Commission 
established a Hurricane Research Advisory Committee composed of researchers, 
engineers, academics, material suppliers, code officials, and the insurance 
industry. The Commission invited FEMA to be a member of the Committee. At its 
first meeting on March 15, 2005, the various members of the Committee made 
presentations to the Commission on their observations of building performance 
and the status of their various studies and reports; FEMA also delivered its 
comprehensive report FEMA 490, Summary Report on Building Performance 2004 
Hurricane Season. The report provides the Committee with the recommendations of 
the MATs on design and construction, building code and regulations, public 
outreach, and critical/essential facilities issues. With FEMAs input and that 
of its other members, the Committee will produce a report that presents 
consensus recommendations on needed changes to Floridas building codes, 
standards, and statutes. The Florida Building Commission will consider these 
changes as it begins its building code update cycle in the summer of 2005.

8.2.1	Statutory Building Code Provisions
The following design criteria are recommended for inclusion into statewide 
design requirements for all construction. The criteria are addressed in Ch. 
553.71 and Ch. 2000-141 of the Laws of Florida (and presented in Section 2.2 of 
this report).

--Evaluate and adopt updated versions of ASCE 7 for design-load determination of 
building structures, building envelope systems, attached equipment, accessory 
structures, and critical and essential facilities. Specific improvements related 
to the design of building envelopes, attached structures, and open structures 
that could mitigate damage observed in Hurricane Charley are not available in 
ASCE 7-98.

--Adopt the windborne debris region defined in ASCE 7 2005 and the debris-impact 
design criteria provided in ASCE 7 2005. The findings of this MAT and the 
Hurricane Ivan MAT determined that these code improvements would have a 
significant effect in reducing damage from windborne debris to buildings and 
contents when a high-wind event strikes.

--Review the exemption in windborne debris regions that allows for residences to 
be designed as partially-enclosed structures with unprotected openings. The 
MAT observed numerous instances where the breach of unprotected glazing led to 
significant damage to building contents that would have been prevented if the 
damaged buildings had been equipped with protected glazing to resist windborne 
debris. The next version of the IRC does not allow for the design of partially 
enclosed structures without protecting glazing. Based on observed damages in 
Hurricane Charley, this exemption should not be allowed for any use (residential 
or commercial) in windborne debris regions.

--Define the Exposure Categories used in design in a manner consistent with ASCE 
7. Refinements to design guidance for Exposure Categories have been included in 
the most recent revisions of ASCE 7. Use of the proper Exposure Category would 
help ensure that full-wind loads are calculated in open areas (Exposure C) where 
speed reductions are not appropriate. 

--Revise Chapter 15C of the Rules and Regulations of Florida to provide window 
protection systems (and a strengthened structure around openings) on Zone II and 
Zone III units being installed in the windborne regions defined by Chapter 16 of 
the FBC. 

8.2.2	General Code Changes Proposed for FBC Consideration
The MAT observed damages across the hurricane wind field that may have been 
prevented had existing code sections been enforced for all design wind speed 
regions or if the code had provided additional design or testing guidance with 
respect to the building envelope and attached structures and equipment. In 
response to the observations, the following items are recommended for inclusion 
in future updates of the FBC and consideration should also be given to 
incorporating applicable modifications into the national model building codes 
for other areas of the country exposed to high-wind speeds:

--Develop and adopt wind resistance and wind-load criteria regarding wind 
resistance for soffits. Wind-driven rain resistance of ventilated soffit panels 
should also be added. Testing Application Standard (TAS) 110 may be a suitable 
test method, although it may require modification. 

--FBC Section 1503 (Weather Protection) should require compliance with American 
National Standards Institute (ANSI)/Single Ply Roofing Industry (now just known 
as SPRI) ES-1 for edge flashings and copings.

--Develop and adopt criteria regarding uplift resistance of gutters and add to 
FBC Section 1503 (Weather Protection)
--Criteria regarding wind and wind-driven rain resistance of ridge vents should 
be added to FBC Section 1503 (Weather Protection). Attachment criteria need to 
be developed, but TAS 110 could be referenced for rain resistance.

--FBC Section 1504 (Performance Requirements) should require compliance with 
American Society for Testing and Materials (ASTM) E 1592 for testing the uplift 
resistance of metal panel roof systems.

--FBC Section 1507.2 (Roof Covering Application) should require compliance with 
Underwriters Laboratories (UL) 2390 and six nails per shingle where the basic 
wind speed is 110 mph or greater, and it should require use of asphalt roof 
cement at eaves, rakes, hips, and ridges (refer to FEMA Hurricane Recovery 
Advisory No. 2  in Appendix D for details).

--Technically-based criteria regarding blow-off resistance of aggregate on 
built-up and sprayed polyurethane foam roofs should be added to FBC Section 1508 
(Roof Coverings with Slopes Less Than 2:12).

--In areas where the basic wind speed is 110 mph or greater, FBC Section 1510.3 
(Recovering vs. Replacement) should require removal of the existing roof 
covering down to the deck and replacement of deteriorated decking. In addition, 
if the existing decking attachment does not comply with the loads derived from 
Chapter 16, installation of additional fasteners to meet the Chapter 16 loads 
should be required.

--FBC Section 1522.2 (Rooftop Mounted Equipment) pertaining to anchoring rooftop 
equipment should be applicable throughout the State of Florida for all wind 
speeds. Criteria should be added that pertain to attaching lightning protection 
systems; however, the criteria need to be developed. These provisions should 
also be included in the mechanical and electrical codes.

--Where shutters other than wood are provided to comply with FBC Section 
1606.1.4 (Protection of Openings), a requirement to label the shutters with code 
described performance information should be added to this section. Without a 
label, is it difficult for building owners to know if their shutters are 
suitable.

8.2.3	Code Changes Proposed for Critical/Essential Facilities and Shelters
To address the poor performance and loss of function of critical and essential 
facilities during Hurricane Charley, the following code changes are recommended. 
Some changes in this section are not directly attributed to damage observed from 
the hurricane, but rather to the resulting loss of function that was observed. 
These types of facilities are expected to perform better than standard 
construction (i.e., these buildings are expected to withstand design events such 
as Hurricane Charley with minimal damage or loss of function). These facilities 
are expected to be functional and operational after hurricanes of significant 
magnitude. 

For shelters and Enhanced Hurricane Protection Areas (EHPAs), the need for 
assurance against failure is significant because these facilities are opened and 
people are invited into a building deemed capable of preserving life and 
protecting against harm during an event. Recommended design guidance and best 
practices for the critical and essential facilities, in addition to the code 
changes cited below, are presented in Section 8.6.

--Critical and essential facilities, at a minimum, should be designed with wind 
loads using an importance factor of 1.15 in accordance with ASCE 7. In addition, 
all code changes proposed in Section 8.2.2 should be required (if they are not 
adopted for all buildings).

--In the SESP, the FL DCA recommends that the design wind speed used for the 
design of hurricane shelters and EHPAs should be the 2001 FBC basic wind speed 
plus 40 mph (Performance Criteria 3, shown in Table F-1 in Appendix F). This is 
also the recommended best practice for shelter design provided in the 2001 FBC, 
Section 423, Part 24 (State Requirements for Educational FacilitiesPublic 
Shelter Design Criteria). To better ensure the adequate performance of shelters, 
the MAT recommends that this guidance be changed to a requirement. 

--For shelters and EHPAs, the minimum debris impact protection should be per 
ASTM E 1996 Category E for a 9-pound 2x4 (nominal) missile traveling at 50 mph. 
These criteria should be required by the SESP and should be used until the 
International Code Councils (ICC's) High Wind Shelter Standard is completed in 
2006/2007 and available for adoption. 

8.3 	Structural (Residential and Commercial Construction)

The generally good performance of structural systems implies that the structural 
design of buildings in high-wind areas has been improved. This improvement is 
the result of implementation of code requirements that better account for the 
forces acting on buildings from wind and windborne debris. In addition to 
considerations recommended in Section 8.2, the following best practices 
regarding the design of new structures and mitigation of older structures are 
strongly recommended.

8.3.1	New Residential and Commercial Structures
It is essential that new buildings be constructed to the 2001 FBC and then to 
the revised 2004 Edition. In addition to the proposed changes to codes and 
statutes presented in Section 8.2, the following should also be considered 
during the design and construction of new buildings:

--Detailing for connections that clearly specifies the continuous load path 
through a building should be provided on residential construction drawings.

--Structural attachments, such as carports, and additions to manufactured homes 
should only be constructed when properly designed and permitted documents show 
the addition is capable of withstanding the wind loads generated. If the 
addition or attachment is not free-standing and is connected to the manufactured 
home for structural support, plans should be prepared that clearly detail the 
connection between the unit and the structure being attached. The design and 
construction should be approved, permitted, and inspected by building officials. 

--Design professionals, building officials, and contractors need to work 
together to improve quality control and inspections during the design and 
construction of buildings in high-wind areas. Codifying additional inspections 
does not guarantee improved construction unless building officials are provided 
the resources or funds for these inspections. All parties need to look at ways 
to ensure buildings are constructed as designed and permitted in hurricane-prone 
regions.

8.3.2	Wind Mitigation for Existing Residential Buildings
Some of the existing residences that performed well in Hurricane Charley were 
older residences that had been retrofitted to resist wind and windborne debris. 
In many instances, the mitigation measures observed by the MAT in these older 
homes were key to the improved performance of the structures. However, in some 
cases, these retrofits were incorrectly performed or were incomplete, and damage 
or failure occurred.

The most common mitigation measure for existing residential buildings observed 
was the installation of metal framing connectors such as clips and straps 
between rafters/trusses and bearing walls. However, in each of the observed 
buildings, the mitigation effort did not address other connections between the 
roof deck and the rafters/trusses. Therefore, only part of the load path between 
the roof covering and the foundation was strengthened. 

At many other existing residences, the attachment of the roof covering system to 
the roof structure below had not been upgraded along with other mitigation 
efforts; most of the houses inspected experienced roof covering damage and 
subsequent damage to their interiors and contents from rain. The MAT concluded 
that mitigation measures should have been part of an overall mitigation plan and 
each measure should have been completely, rather than partially, carried out.

The IBHS (http://www.ibhs.org) and the Federal Alliance for Safe Homes 
(FLASH)(http://www.flash.org) have comprehensive guidelines and plans for 
retrofitting existing homes for wind resistance. The mission of both 
organizations is to reduce the loss of life and property damage from natural 
disasters by promoting construction techniques that typically exceed those of 
the minimum adopted building code. Their guidelines are strongly recommended and 
highly relevant for mitigating damage from events such as hurricanes. The 
programs provide recommendations for retrofitting existing buildings from the 
roof deck to the foundations. Some of the highlights and focuses of their 
mitigation programs are outlined below.

For wall openings:

--Windows  Cover windows with impact-resistant shutters or replace them with 
impact-resistant windows

--Garage doors  Replace garage doors with wind and impact-resistant garage 
doors or have a design professional specify bracing for the garage door and 
strengthen methods for the track. Figures 8-1 and 8-2 show a plan view of a 
typical garage door and a recommended reinforced horizontal latch system for a 
typical garage door, respectively.

Figure 8-1. Illustration. Plan view of a typical garage door. This illustration 
shows the exaggerated deflected shape of the door under high winds. The 
locations of detail views shown in Figures 8-2 and 8-3 are shown.

Figure 8-2. Illustration. Detail A  recommended reinforced horizontal latch 
system for a typical garage door. This illustration shows how the garage door 
latch can be upgraded with additional metal plating by the manufacturer and the 
installation of a bracket to strengthen the latch connection. The bracket is 
anchored to the garage door jamb with wall anchors and expansion bolts. the 
installation of horizontal metal or wood girts to strengthen the door is also 
shown.

--Replace doors with wind and impact-resistant doors or install head and foot 
bolts to engage door frames with a longer throw length (a minimum of 1 inch); 
use additional connectors to secure door frames to supporting walls
For roof coverings and roof decks (see FEMA Hurricane Recovery Advisories Nos. 1 
and 2 in Appendix D):

--When installing new asphalt shingle roof covering, perform the following 
activities:
	--Remove the existing roof covering to expose the roof sheathing
	--Remove the bottom row of sheathing at the eave
	--Install straps/clips at the roof-to-wall connections
	--Brace the gable end walls
	--Replace any damaged or deteriorated sheathing panels
	--Refasten all sheathing with 10d common or 8d ring shank nails spaced at 
	4 inches on center on the edges and 6 inches on center in the field

--If the roof covering is not being replaced, perform the following activities:
	--Strengthen the roof deck from inside the attic by using a caulking gun 
	to apply a 1/4-inch bead of wood construction adhesive (certified to AFG-
	01 or ASTM D 3498) at the intersection of the roof deck and truss/rafter 
	on both sides
	--Brace the gable end walls and ensure the bottom chord of the gable end 
	trusses are secured to the top of the wall
	--Install straps/clips at the roof to wall intersection from inside the 
	attic or by gaining access from the exterior

8.3.3	Wind Mitigation for Existing Commercial Buildings
The MAT observed some existing commercial (non-residential) buildings that were 
mitigated to resist additional wind loads or to protect glazing from windborne 
debris. Although this report clearly states that significant contents damage 
claims may be reduced by installing protection systems for glazing, the building 
structure or other portions of the building envelope should still be evaluated. 
At the Charlotte County Sheriffs office and EOC, the roof of this pre-
engineered building was lost over the front third to half of the building, 
despite having shutters protecting the glazing. Even if this facility was not 
used for critical or essential operations, the end result for any tenant would 
have been the same; that is, the contents of the building were completely 
destroyed when the roof covering was lost and rain soaked the interior. It is 
important to remember when retrofitting existing buildings that the building 
will remain vulnerable unless all structural and envelope issues are addressed 
comprehensively.

The MAT observed many rolling and sectional garage doors on critical or 
essential facilities and at commercial and industrial buildings that failed 
during the hurricane, resulting in large openings in the building envelope. A 
typical failure point was the roller and track connection. Designers should 
ensure that wind-resistant doors, all tracks, closure mechanisms, and 
attachments to the building structure are properly designed and installed. For 
these doors, the tracks need to be reinforced (along with the attachment of the 
tracks to the wall and ceiling) or the door itself needs to be supported by 
removable columns or supports that will reduce the loads being transmitted 
through the roller/track connection. These removable supports should be 
installed on garage doors when a hurricane warning is issued. Figure 8-3 shows a 
typical garage door failure and recommended assembly improvements applicable for 
commercial and residential applications.

Figure 8-3. Illustration. Detail b  typical garage door failure at the edge and 
recommended assembly improvements. This illustration shows the failure mode of 
bracket and glider track under wind pressure, and a recommended retrofit that 
involves installing a heavier track and bracket and securing the bracket to the 
exterior wall with an expansion anchor.

8.4	Accessory Structures/Attachments

Given the prevalence of failures of aluminum structures (such as pool cages and 
carports), consideration should be given to improving their designs. Until the 
2004 FBC is adopted (and statutes restricting the referencing of improvements to 
ASCE 7 and the IRC are rescinded), fabricators and engineers of aluminum 
structures can opt to use the readily available AAF Guide to Aluminum 
Construction in High Wind Areas. Alternatively, the MAT recommends the 
following: 1) provide additional anchors at the corner post connections to the 
concrete (these posts should be more securely fastened to the concrete than the 
intermediate posts); 2) ensure that walls parallel to the primary building are 
more resistant to wind forces parallel to those walls by using tension cable 
bracing, solid K bracing, or other methods; 3) provide lateral bracing in roof 
planes by using rigid diagonal structural members; and 4) use stainless steel 
screws to avoid commonly observed corrosion. 

For existing attached structures, it is recommended that these structures be 
evaluated to determine if they are structurally sound for the wind region in 
which they are located. Because prescriptive analysis guidance may not be 
available, it may be advantageous to have a design professional analyze the 
structures to determine whether they are capable of withstanding wind pressures 
without failure and to determine the implications to the attached buildings if 
attached structures collapse or are torn away. In addition, it is recommended 
that detached structures be analyzed by a professional to determine their 
ability to withstand windstorm events. This analysis should include a review of 
the anchoring of lightweight structures. The attention to the code guidelines 
for wind-resistant design is often neglected in these structures. 

Some contractors may view the use of best practices that meet or exceed code 
minimums, such as the AAF Guide to Aluminum Construction in High Wind Areas, as 
an impediment due to a false perception of high costs associated with these 
engineering practices in the competitive arena of home contracting. However, 
some contractors understand that providing durable structures is a sound 
business practice that enhances their reputations and reduces their liabilities. 
Some measures to improve the survivability of aluminum structures are simple and 
inexpensive (e.g., strengthening the anchoring of corner posts and installing 
additional bracing). For this reason, they should be utilized by all aluminum 
contractors.

8.5 	Architectural, Mechanical, and Electrical 

To improve the performance of the building envelope and rooftop equipment, the 
following action items are recommended in addition to the code revisions 
identified previously.

--Wind design guides. 
Design guides need to be developed for gutters and downspouts, soffits, metal 
panel systems, continuous ridge vents (including means to provide secondary 
protection from water intrusion if the vent blows off), rooftop mechanical and 
electrical equipment, and lightning protection systems (LPSs). The guidance in 
FEMA Hurricane Recovery Advisories No. 1 and No. 2 (Appendix D) should be added 
to the Residential Asphalt Roofing Manual published by the Asphalt Roofing 
Manufacturers Association) and to The NRCA Steep-Slope Roofing Manual published 
by the National Roofing Contractors Association (NRCA). The guidance in FEMA 
Hurricane  Recovery Advisory No. 3 (Appendix D) should be considered for 
incorporation into the Concrete and Clay Tile Installation Manual published by 
the Florida Roofing, Sheet Metal and Air Conditioning Contractors Association, 
Inc. (FRSA) and Roof Tile Institute (RTI).

--Loads and attachment. 
It is recommended that designers calculate loads on the building envelope and 
rooftop equipment and specify/detail adequate attachment to resist the loads. A 
minimum safety factor of 2 is typically recommended.

--Roof coverings.
When re-roofing, tear-off rather than re-covering is recommended in areas where 
the basic wind speed is 110 mph or greater. This will allow inspection of the 
integrity and attachment of the roof sheathing. If the existing decking 
attachment does not comply with the loads derived from the current building 
code, installation of additional fasteners to meet the code loads is 
recommended; contractors are reminded that in-process inspections are required 
by many jurisdictions. Further, it provides access to the roof deck so secondary 
underlayments may be installed to improve the roof decks resistance to water 
intrusion. Specific system/component recommendations are:

Asphalt shingles. Guidance given in FEMA Hurricane  Recovery Advisories No. 1 
and No. 2 (Appendix D) is recommended. In addition, installers need to follow 
manufacturers installation instructions with respect to starter strips and nail 
locations. Manufacturers should re-evaluate the attachment of factory-laminated 
tabs (Figure 5-27). Loss and blow-off of the tabs may be reduced if additional 
quantities of adhesive, or a stronger adhesive, is used during the production of 
the shingles.

Metal panels. It is recommended that uplift resistance be based on ASTM E 1592. 
For panels with concealed clips, it is recommended that clip locations be chalk-
lined to ensure that they are not excessively spaced or different from 
manufacturers' recommendations. It is also recommended that designers specify 
close spacing of fasteners at eaves, and hip and ridge flashings (e.g., spacing 
in the range of 3 to 6 inches on center, commensurate with the design wind 
loads).

Tiles: It is recommended that foam-set manufacturers re-evaluate their 
installation recommendations in order to simplify the number of options and to 
clarify the requirements. It is also recommended that they re-evaluate their 
training and certification programs, because it was evident that many foam-set 
roofs were installed improperly, most likely by inadequately trained workers. 
Guidance given in FEMA Hurricane  Recovery Advisory No. 3 (Appendix D) addresses 
both of these issues and should be implemented.

It is recommended that FRSA and RTI re-evaluate the use of a safety factor of 2 
for mechanically attached systems. Field observations of some roofs indicated 
that tile blow-off occurred at wind speeds less than those predicted by the 
resistance tables in the Concrete and Clay Tile Installation Manual. This 
difference between predicted and actual performance may be due to the static 
test method used to evaluate wind resistance. However, tiles are dynamically 
loaded during hurricanes. With dynamic loading, minor oscillating of down-slope 
ends of the tiles may induce fatigue loading, which, during a hurricane, allows 
the oscillating tiles to jack the fasteners out of the deck, or allows the nail 
holes through the tiles to be enlarged enough to allow tiles to pull over the 
fasteners. Until a dynamic test method can be developed, the existing test 
method could be used with a higher safety factor (e.g., 3) applied to the 
ultimate resistance.

Similarly, it is recommended that the foam-set manufacturers re-evaluate the use 
of a safety factor of 2. With foam-set attachment, there is an opportunity for 
variation in size and placement of the foam paddies. Also, as discussed above, 
the static test method may over-predict actual performance. A higher safety 
factor (e.g., 4) may be a more appropriate value to use to account for these 
application and testing concerns.

Edge flashings, copings, and gutters. Successful performance of edge flashings, 
copings, and gutters is vital to avoid progressive lifting and peeling of roof 
membranes. For edge flashings and copings, compliance with 2003ANSI/SPRI ES-1 is 
recommended. However, because ES-1 does not incorporate a safety factor, it is 
recommended that a safety factor of 2 be applied to the ultimate resistance 
values obtained from testing (a safety factor of 3 is recommended for critical 
and essential facilities). 

Further, to avoid progressive failure in the event of gutter, edge flashing or 
coping uplift, it is recommended that a bar be placed over the roof membrane 
near the edge flashing or coping (Figure 8-4). The purpose of the bar is to 
provide secondary protection against membrane lifting and peeling in the event 
that the edge flashing/coping fails. A robust bar specifically made for bar-over 
mechanically-attached single-ply systems is recommended. The bar needs to be 
very well anchored to the parapet or deck. Depending upon design wind loads, 
spacing between 4 and 12 inches on center is recommended for the bar anchors. A 
gap of a few inches should be left between each bar to allow for water flow 
across the membrane. After the bar is attached, it is stripped over with a 
stripping ply.

Figure 8-4. Illustration. Continuous bar near the edge of edge flashing or 
coping. If the edge flashing or coping is blown off, the bar may prevent a 
catastrophic progressive failure. Source: FEMA 55, Coastal Construction Manual, 
2000. This illustration shows details for the installation of flashing and 
coping.

Design guidance and test methods are lacking for gutters. Therefore, it is 
recommended that designers exercise their professional judgment in specifying 
and detailing gutter uplift resistance.

--Windows. It is recommended that the window/curtain wall industry re-evaluate 
the test pressures that are currently used to  assess resistance to wind-driven 
rain. Although this has not been an issue in the past, as building performance 
is improved and water infiltration due to failed envelopes is reduced, the 
damage due to wind-driven rain infiltration is becoming more pronounced. With 
incorporation of more realistic test pressures, development of more water-
resistance assemblies is necessary.

--Motorized shutters. Motorized shutters should be manufactured with a manual 
override. This will allow deployment of the shutters prior to a hurricane, even 
if power has been lost. After a hurricane, they can be rolled up even if the 
electrical power has not been restored; this will facilitate drying the building 
if water infiltration has occurred and speed recovery.

--Rooftop mechanical and electrical equipment. For attachment of rooftop 
equipment, a minimum safety factor of 2 is recommended due to uncertainties 
pertaining to load and resistance in currently required codes. It is recommended 
that cowlings on exhaust fans be anchored with cables to curbs, and that access 
panels that are not securely attached by the manufacturer be field modified 
(guidance is provided in FEMA 424, Design Guide for Improving School Safety in 
Earthquakes, Floods, and High Winds). It is also recommended that special 
attention be given to attachment of LPSs, per guidance provided in FEMA 424.

--Weatherstripping at exterior doors. Specifying wind-driven rain-resistant 
weatherstripping at exterior doors is recommended. Although it has not been an 
issue in the past, as building performance is improved and water infiltration 
due to failed envelopes is reduced, the damage due to wind-driven rain 
infiltration at doors is becoming a more significant problem. FEMA 424 provides 
weatherstripping guidance. 

When the basic wind speed is greater than 120 mph, some leakage should be 
anticipated when design wind-speed conditions are approached. One approach to 
minimize infiltration damage would be to design a vestibule to provide more than 
one level of protection against rain water infiltration, in addition to robust 
weatherstripping. With this approach, both the inner and outer doors can be 
equipped with weatherstripping, and the vestibule itself can be designed to 
tolerate rain water intrusion. 

8.6	Critical and Essential Facilities (Including Shelters)

Designers should be reminded that codes and standards recommend the minimum 
design requirements for facilities (even critical and essential facilities); 
thus, implementing known best practices for high-wind design above the required 
minimums is prudent. To achieve building performance that will not result in the 
loss of function of the facility, the following are recommended in addition to 
the proposed code revisions provided in Section 8.2.3. 

--Expand the use of the critical and essential facility designation. ASCE 7 
Table 1 defines which buildings are required to be classified as critical and 
essential facilities (i.e., Category III and IV buildings).  However, building 
owners and their design professionals should not consider Categories III and IV 
to be an all-inclusive list. Other buildings may be vital in the response before 
and during, and recovery following a hurricane, or they may house functions that 
need to remain operational during an event. For example, a medical office 
building (MOB) is not a Category III or IV building, but the poor performance of 
a MOB could adversely affect the functioning of the hospital. Therefore, 
classifying MOBs that are integrated with hospitals as critical or essential is 
recommended. Similarly, nursing homes are not specially mentioned in ASCE 7 
Table 1; however, health care facilities with 50 or more resident patients are 
classified as Category III. Although an independent living or assisted living 
facility would typically not be considered Category III, a skilled nursing or 
Alzheimers facility (regardless of size) would benefit from being classified as 
Category III.

--Prioritize the critical and essential facilities. All critical and essential 
facilities are important, yet some are more critical than others. Because of the 
realities of funding limitations to mitigate wind effects for both new and 
existing buildings, building owners and their design professionals should 
prioritize their facilities. For example, buildings sheltering large numbers of 
people (e.g., greater than 1,000) and buildings that have regional importance 
(e.g., a county EOC or regional hospital) should be designed, constructed, and 
maintained more conservatively than normal critical and essential facilities. 
Existing critical and essential facilities could also receive the highest 
priority for mitigation (retrofit) projects. 

--Siting. New critical and essential facilities and, specifically, shelters 
should not be constructed below the 500-year flood elevations or within a 
designated storm surge inundation area. Evaluation of existing shelters located 
in storm surge inundation zones that were opened during Hurricane Charley is an 
operational issue that was beyond the scope of this building-focused MAT report. 

--Detailing and notations on the building plans. Designers should clearly 
indicate on the plans the area of the facility that was designed to function as 
a high-wind shelter or hardened area. Further, the designer should provide 
additional details of the portions of the buildings structure and envelope 
elements to ensure that the construction requirements or differences for this 
portion of the building are clearly understood by the builder and the building 
official. Additional notes should also be provided that clearly indicate the 
design criteria used for this facility (or portion thereof) and maximum design 
pressures should be stated for the main wind force resisting system (MWFRS) and 
for components and cladding (C&C) systems. Specific references to design 
assumptions from ASCE 7 and FEMA 361, Design and Construction Guidance for 
Community Shelters should be provided.

--Material selection. Regardless of whether the FBC, ASCE 7, model building 
codes, or FEMA 361 is used to design the critical or essential facility, other 
design measures should be taken for design of the building's structural and 
envelope systems, and rooftop equipment. Structural systems that have a proven 
record of excellent high-wind performance include reinforced cast-in-place 
concrete structures (including insulated concrete forms), reinforced masonry 
structures with concrete or heavy metal decks, and steel frame systems with 
debris-resistant exteriors. Both FEMA 361 and FEMA 424, Design Guide for 
Improving School Safety in Earthquakes, Floods, and High Winds, provide detailed 
guidance on material selection for structural and building envelope systems. 
Although FEMA 361 was developed for shelter design and FEMA 424 was developed 
for schools, much of the information is applicable to other types of critical 
and essential facilities. Finally, a comprehensive design guide addressing 
retrofitting and mitigation of existing essential facilities should be 
developed. This guide would benefit many communities with older facilities. 

--Peer review process. To improve the quality of design, contract drawings and 
specifications for new construction and remedial work on existing building 
envelopes and rooftop equipment should undergo rigorous peer review prior to 
permitting and construction. This would ensure important details are not 
overlooked or under-designed.
--Construction contract administration. For new construction and remedial work 
on existing building envelopes and rooftop equipment, more rigorous submittal 
review and field observation (inspection) should occur than is the case with 
non-critical and essential buildings. This is imperative for maintaining the 
integrity of the building envelope.

--Code requirements. The only special criteria for critical and essential 
facilities in the FBC, ASCE 7, and the model building codes is the importance 
factor (I). The importance factor adjusts the mean recurrence interval to the 
facility type being designed. However, for these facilities, this adjustment 
will typically increase the loads by only 15 percent. Other criteria need to be 
added to the code and were presented in Section 8.2. 

--Maintenance and repair. To protect from adverse facility degradation as they 
age, critical and essential facilities should be periodically inspected, 
maintained, and repaired. Emphasis should be on the buildings envelope and 
rooftop equipment because these are the components most prone to degradation. 
The roof and rooftop equipment should be inspected twice a year. Windows, doors, 
and wall coverings should be inspected at 5-year intervals. In addition, special 
inspections of the entire facility (both building structural and envelope 
systems) should be conducted after storms with wind speeds in excess of 90 mph 
3-second peak gust winds. 

8.7	Design Guidance and Public Education

In order to reduce the damages caused by building structural and envelope 
failures, better guidance and public education needs to be developed and 
provided to design professionals, contractors, and the general public who 
design, construct, and live in hurricane-prone regions. The following items are 
provided for consideration:

8.7.1	Design and Construction Guidance
Design professionals are in need of additional guides to provide methodologies 
and best practices when code guidance is vague or unclear. For instance, it was 
common to see fasteners for roof coverings and wall cladding spaced too far 
apart, fasteners that were too small, and connections that were too weak. 
Enhanced details were seldom observed. Numerous examples of building envelope 
component failure were observed, especially when well-established basic 
construction practices were not implemented, such as compliance with minimum 
edge distance spacing for fasteners. Unless designers and contractors understand 
wind-resistance issues, envelope and equipment failures will continue to occur. 
The following list identifies where improved design, construction, and testing 
guidance is needed so that code compliance can be better achieved.

--Pre-engineered metal buildings. The MAT observed numerous pre-engineered metal 
building failures due to corrosion of the main structural framing members. To 
improve the performance of these buildings, main framing members of all pre-
engineered buildings that are 10 years of age and older should be inspected at 
3-year intervals by a registered structural engineer. A report of the buildings 
structural adequacy should be submitted to the building official and the 
building owner or manager. This type of evaluation could be combined with a 
building maintenance program to ensure the buildings will perform as originally 
designed.  

--Roof coverings, gutters, and downspouts. A design guide, test method, and 
building code criteria need to be developed for gutters. The design guide should 
also address attachment of downspouts. Technically-based criteria need to be 
developed and codified for aggregate surfacing on built-up and sprayed 
polyurethane foam roofs. To decrease susceptibility of tiles to windborne debris 
damage and subsequent blow-off from the roof, development of tiles with improved 
ductility via internal or backside reinforcement or bonding film is recommended 
in hurricane-prone regions (i.e., development of a tile akin to laminated 
glass). Although it is currently a low priority, research is needed on wind 
resistance of roof walkway pads.

--Rolling and sectional doors. Because of their large size, high loads can be 
induced on frame fasteners. Designers and contractors should give special 
attention to fastener type, and size and spacing used to attach the frame. If 
the frame is attached to wood blocking, attention should also be given to the 
blocking attachment. If the fasteners are placed in concrete or masonry, 
adequate edge distances should be maintained. 

--Soffits. Design guidance is needed for the attachment of soffits, including 
design of baffles or filter media to prevent wind-driven rain from entering 
attics.

--Rooftop equipment. Design guidance and building code criteria are needed for 
the attachment of condensers and rooftop mechanical equipment (including outside 
ductwork). Air conditioning condensers can be anchored to a secure mounting for 
little cost. Such anchoring would greatly reduce damage to the Freon and 
electrical connections to the compressors, thus decreasing the amount of time 
occupants would be without air conditioning. Building owners and homeowners also 
need to be educated to inspect exterior connections and fasteners for wear, 
corrosion, and other deterioration that weakens the integrity and becomes 
breakable in a hurricane.

--Other exterior devices and equipment. Other exterior devices, such as pool 
equipment, gas heaters, and heat pumps, should be evaluated and secured as 
needed. These devices may already be anchored well enough by plumbing lines, and 
additional anchoring may not be necessary. However, property owners should be 
educated about performing an appropriate inspection of their homes to evaluate 
the need to secure objects, including childrens swing sets, aboveground pools 
(not filled), barbeque grills, and storage sheds. Because of the number of roof-
mounted solar water heater collectors that were torn off homes during 
hurricanes, it is recommended that their attachment to the roof be carefully 
inspected by a qualified professional to be sure they are secured well enough to 
withstand anticipated wind pressures. 

--Electrical and communications equipment. Design guidance and code criteria are 
needed for attachment of LPSs, communications towers, and satellite dishes.

--Test methods. Some of the methods used to test building envelope assemblies 
are inadequate. Virtually all of them are static tests. Static testing is 
suitable for some assemblies, but other assemblies should be dynamically tested 
in order to obtain a more realistic measure of their wind resistance. For those 
assemblies where it would be prudent to test dynamically, but dynamic test 
methods are not currently available, higher safety factors should be used.

--Manufacturers instructions. There were numerous instances of products being 
installed in a manner that was a significant deviation from manufacturers 
installation instructions. This points to a need for better training of the 
workforce, establishing better quality control (i.e., contractors inspecting 
their work) and more frequent quality assurance (i.e., field observations by a 
qualified party other than the contractor, such as an engineer or building 
official). 

--Human intervention. Building owners and homeowners need to be educated about 
pre-storm activities, such as installation of shutters (if glazing is not 
laminated), installation of removable stiffener bars at garage doors (where 
applicable), and tying down or removing loose items from roofs and yards. They 
should also be educated about post-storm activities, such as quickly removing 
wet materials from within buildings and drying out the buildings. 

8.7.2 Public Education and Outreach
Much has been learned in the past three decades regarding practices that need to 
be implemented to achieve good building performance during strong hurricanes. 
Although improvements are still needed with respect to design guides, test 
methods, building codes, and construction/inspection practices, it is clear that 
many of the failures observed after Hurricane Charley were not caused by current 
code inadequacies, but caused by instead from the failure of designers, 
manufacturers, building officials, and contractors to implement the current 
state of knowledge with respect to buildings located in hurricane-prone regions. 
A renewed, state-wide comprehensive educational effort is needed to avoid the 
hurricane building damage cycle, wherein buildings are constructed, damaged, 
repaired, or rebuilt, and then damaged again in a future severe weather event. 
The following specific action items are recommended:

--Building owners and homeowners. Owners need to be educated in a number of 
areas: 

--The need to adequately budget for a construction project, so that 
appropriate mitigation measures can be implemented

--The need to select a design and construction team that is knowledgeable 
about designing and constructing in hurricane-prone regions, and who will 
execute the work in a diligent and technically proficient manner utilizing 
state-of-the-art best practices 
       	
--Preparations to be taken prior to hurricane landfall 

--Steps to be taken after the hurricane passes (e.g., having the building 
inspected for damage, having emergency repairs performed, and drying out 
the building)

--If the building is damaged, having it rebuilt in a manner that protects 
against future damage 

--The need to periodically inspect exterior connections and fasteners for 
wear, corrosion, and other deterioration that weakens the integrity and 
becomes breakable in a hurricane

To facilitate these educational goals, pamphlets tailored to homeowners and 
commercial/governmental owners should be developed, along with strategies for 
distributing this information to owners (possibly during the sale of a home or 
business). Enlisting the assistance of real-estate companies and organizations 
such as the Building Owners and Managers Association (BOMA) and providing public 
service notices to television programs at the start of each hurricane season 
should be pursued.

--Architects/engineers/consultants. From the damage observed to both old and new 
buildings, it is clear that some design professionals working in hurricane-prone 
regions still struggle with the design and detailing of hazard-resistant 
construction. Although it appears that in most cases the structural systems 
(MWFRS) are receiving proper attention, many design professionals falter and 
struggle with the design of building envelopes and rooftop equipment; this 
indicates a need for substantial improvement in their technical proficiency in 
this aspect of building design. A variety of educational tools could be used to 
assist the designers, including monographs, web-based tutorials, and seminars. 
Colleges and universities located in hurricane-prone regions should consider a 
curriculum that emphasizes hurricane-resistant design for current students and 
continuing education for design professionals. 

--Building officials. Coastal area building officials, plan reviewers, and 
inspectors should be required to attend annual seminars specially designed to 
share lessons learned and to train the building officials to look for items 
that may cause failure of a structure or building components during hurricane 
events. These items include unbraced gable ends, missing truss bracing, truss 
anchorage, and anchorage of the windows and doors. Quality of construction also 
depends upon knowledge of the building officials and enforcement techniques of 
the building department. 

--Contractors. Many contractors, particularly those involved in constructing 
building envelopes and installing rooftop equipment, could be better trained in 
the installation and use of fastening and anchoring systems. For construction 
trades, visual tools that use videos/DVDs and on-the-job or classroom mock-up 
training that highlights the failures that occur when simple anchoring 
techniques are not applied may be beneficial. Trade schools in hurricane-prone 
regions should include courses on hurricane-resistant construction in their 
curriculum.

--Manufacturers. Many manufacturers of building envelope materials and rooftop 
equipment are also in need of education regarding performance of their products 
during hurricanes. With increased knowledge, manufacturers will be better 
equipped to provide special guidance for use of their products in hurricane-
prone regions and will be better equipped to develop improved products and 
systems for these areas. With a better educated manufacturing sector, 
manufacturers could serve a vital educational role when they interface with 
designers and contractors.

--Associations. It is recommended that associations, institutes, and societies 
representing design professionals, contractors, and manufacturers take an active 
role in developing hurricane-resistant design and/or construction educational 
materials and promote them, along with educational materials developed by 
others, to their members.

--Incentives. The greatest educational challenge is to get those in need to take 
advantage of educational materials that are available. To the extent possible, 
materials and seminars should be free or of minimal cost. To achieve this goal, 
governmental (Federal, state, and local) funding may be necessary. However, the 
ultimate incentive likely lies with building owners and homeowners, and the 
decisions they make in selecting design and construction teams that will produce 
the best product for their dollar.

--Public education on rain water damage. To reduce property losses and the 
negative impact to business owners whose businesses and homeowners whose homes 
were damaged, business owners and homeowners should be educated on how rain 
water damage can occur to buildings. The purpose of the education would be to 
encourage all property owners to protect their businesses and homes from the 
entry of rain water. Key points to highlight include:

--Prolonged rain falling on damaged buildings can result in significant 
water damage to their business or home.

--It is not uncommon for wind-driven rain, sometimes traveling in excess 
of 100 mph, to wet all interior surfaces of a building.

--Associated pressure differences across walls, windows, doors, soffits, 
etc., can lead to the entry of damaging amounts of rain water into a 
business or residence.

--Wet or flooded buildings are unlikely to have electricity for several 
weeks; this can present long- and short-term problems for drying the 
building if auxiliary power is not available.

--Basic ventilation and removal of water may not be possible if motorized 
shutters cannot be opened; there is typically no means for 
dehumidification without power. 

--High temperatures and high humidity are conducive to the growth of mold 
and odors.

Similarly, builders and remodelers might benefit from education related to best 
practices and methodologies to minimize rain water-entry issues. If they are 
aware of these issues, they may be encouraged to suggest to business owners and 
homeowners cost-effective measures to make buildings more water- and wind-
resistant. Even though there are several relatively inexpensive means that can 
be taken to minimize rain water entry, most builders and remodelers are not 
aware of the vulnerabilities of buildings.