Building Research Division
Florida Solar Energy Center
damage provides the "opportunity" to make homes
energy efficient and more resilient to future storms. (Photo
credit: Bill Young)
With the state of Florida slammed by a record four hurricanes
in the summer of 2004, many homes need re-roofing and repair.
Following the recent disasters, it is very difficult to obtain
the services of a roofer. Meanwhile, many Floridians are without
power and physically suffering without air conditioning. Further,
many homes sustained floor water damage– particularly in
carpeted or wood floor areas.
While coping with the aftermath of the hurricanes is difficult,
Florida Solar Energy Center® (FSEC®) buildings research
offers practical methods when making repairs. FSEC research findings
can be applied to make repaired homes more energy efficient and
comfortable in the event of power outages and more resilient when
faced by future storms.
If you have to re-roof, choosing the right roof can result in
a cooler home, reducing the energy used when you air condition
and making conditions more comfortable when power is not available.
|A white metal
roof can reduce space cooling by 20%. (Photo
credit: Steven C. Spencer)
FSEC research spanning the last decade has clearly shown that
a white reflective tile or a white metal roof can reduce space
cooling by 20% or more. More recent testing has shown that unfinished
Galvalume roofs– which look like brushed aluminum–
can provide about half that cooling benefit. Light colored tile
roofs can provide similar improvements in performance. Tests performed
by FSEC show the temperature in attics covered by dark shingle
roofs can reach as high as 140 degrees on summer days. Meanwhile,
a white metal or white tile roof never gets much hotter than the
outside temperature, with light colored tile or metal registering
Though metal roofs can cost twice as much as shingle roofs, and
tile roofs three times as much, they last at least two to three
times as long and keep the home much cooler. That means average
savings of more than $100 per year in reduced air conditioning,
as well as a much cooler home interior in the event that no air
conditioning is available– such as the current experience
of many Florida homeowners without power in the wake of the hurricanes
Even if you must go with shingles when re-roofing (many roofs
cannot support tiles without physical strengthening), it is best
to choose the lightest-colored shingle roof and consider installing
a foil radiant barrier on the underside of the roof decking. Testing
performed for the Florida Power and Light Company showed that
simply choosing white shingles would reduce space cooling by 4%
and choosing lighter colored shingles with a radiant barrier should
cut cooling costs by twice that or more. All these options will
provide slightly better comfort on the interior when air conditioning
is not available.
A standard, 2,500-square-foot roof will cost $5,000 to $6,000
to replace with shingles, $8,000 to $12,000 with metal, and about
$15,000 with concrete barrel tile. Many homes cannot support the
weight of a tile roof without extensive work beforehand, making
metal roofs such as Galvalume the more practical choice for many.
A Stronger, More Forgiving Roof
When houses are exposed to hurricane forces, roofs are most susceptible
to damage, followed by walls
and openings, and then foundations. Data collected by HUD studies
after major hurricanes show clearly that roofs are damaged more
often than any other building component. Water penetration was
a major problem whenever roofing material was removed by wind
action. For steep roof systems, many roofing failures occurred
at the ridge or gable ends where wind-induced forces were the
highest. Gable ends were consistently found to increase the chances
of roof failure in a number of forensic tests after hurricanes.
roofs typically fail during hurricanes, as seen on FSEC's
(Photo credit: Nick
The most common roofing systems to fail during hurricanes are
typically the lower-cost shingle roofs–particularly those
applied with staples, which are now forbidden by current Florida
building codes. Properly attached tile and metal roofs typically
have done better in such storms as evidenced in numerous post-storm
studies done by U.S. HUD after Hurricanes Andrew, Hugo and Iniki
in the 1990s.
However, construction quality matters with all roofing systems.
Properly installed hurricane straps, nails and screws are a must.
Tile roofs should be installed with nails or screws rather than
mortar-set which is more prone to failure. While tile and metal
have done better after the storms, a properly attached shingle
roof with high-quality architectural grade shingles should do
well. In any case, home owners should obtain multiple bids and
deal only with licensed, reputable contractors in making roof
repairs. After the storm, this is exceedingly difficult, however,
as many homeowners with leaking roofs are looking for immediate
solutions, and that demands improvised fixes-such as tarpaulins.
Unfortunately, just as shingle roofs tend to have the shortest
life expectancy in Florida’s difficult climate (15-20 years),
they also often fail when exposed to severe winds, leaving many
homeowners with shingle roofs looking for roofing help at the
In spite of the many benefits of the lighter color tile or metal
roofs, many homeowners still go with the shingles. They’re
cheaper to install, and they’re often chosen in darker colors
for aesthetic reasons. Wind-resistant shingles are available,
although they are more expensive. Generally, three-tab self-sealing
shingles with a six-nail application pattern should be preferred.
However, even with shingles you can choose lighter colored shingles
at no incremental cost. Also, adding good ridge vents to a roofing
system is a smart idea. The HUD post-hurricane research found
that effective ridge ventilation was important in preventing sheathing
uplift during hurricanes. Finally, if you install another shingle
roof and have good attic ventilation, you ought to consider adding
an attic radiant barrier that will help abate attic heat gain.
Check out the Florida Solar Energy Center’s web site (http://www.fsec.ucf.edu)
for detailed information on radiant barrier installation.
Thus, a key advantage is to install a roofing system with greater
longevity and resistance to storm damage. Tile or metal roofs
typically have at least twice the life expectancy of shingle roofs
and, if properly installed, can resist storms long into their
service life. Indeed, it is possible to see many metal roofs installed
in central Florida in the early 1900s that are still providing
reliable service. Some tile roofs in South Florida are still in
use though they were installed in the 1950s. The key point is
to choose a stoutly-installed cooler roofing system (e.g. light
colored tile or metal, properly adhered so that your home will
run cooler, you will be less likely to suffer storm damage, and
you will enjoy year-round savings on air conditioning.
Based on the HUD research, the following are other issues to
consider in making your roof stronger:
- If installing a new roof with trusses, consider a hipped roof
rather than one with gable ends, which tend to be more storm
damage prone. Highly pitched roofs with gable ends are particularly
vulnerable. This is also the time to minimize roof penetrations
(e.g. from kitchen and bath vents) and run them out the soffit.
You may also want to consider the new technique of unvented
attics; see http://www.baihp.org/data/CFRes/index.htm for a case study.
- If the building has gable ends, plan to have the ends stoutly
braced. Do not install gable vents, which are prone to water
leaks during wind-driven rain.
- Plan to limit overhang width and instead use awnings, Bahama
shutters or other means to shade windows
- If the attic has soffit ventilation, it is important that
ridge venting be provided as well to prevent dangerous uplift
on sheathing during high winds
- Verify that hurricane straps, nails (shingles) and screws
(tile) are properly used.
- Re-nail any sheathing that is suspect.
- Be sure to get all roof vents and caps examined and replaced
Windows and Doors
Most Floridians know that using hurricane shutters for windows
is an important measure, but most have not considered how some
systems such as louvered-Bahama shutters or awning shutters can
provide shading for windows when not used to protect from storms.
Such shading devices can also be deployed more rapidly and with
less nuisance than stored plywood or storm panels. Not only will
proper window shading reduce air conditioning, but it will also
improve comfort when air conditioning is not available. Finally,
some of the newer impact-resistant glass systems come with double-strength
laminated glass with solar control properties which can cut down
on heat transmission– a desirable characteristic nearly
year round in Florida’s climate.
It is also useful to improve the anchorage of windows to openings
that are old or in poor repair– particularly for a large
expanse of glass such as sliding glass doors. Also, garage doors—particularly
double-wide garage doors—can be strengthened to improve
With the recent hurricanes, many homeowners have suffered water
damage with soaked carpets, and without power to dry them. Many
carpets have been ruined, and there is the greater threat of mold
Back during the 1960s, prior to the advent of widespread air
conditioning and at a time when hurricanes in Florida were more
prevalent, many Florida homes had tiled or terrazzo floors. Not
surprisingly, a tiled or terrazzo floor is much more forgiving
relative to water damage. Clean up is simple. There are also no
carpets to create a potentially devastating mold problem.
Perhaps just as important, FSEC research has shown that tiled
floors feel cooler due to contact with the cooler ground underneath
(the deep ground temperature in any location is equal to the average
annual air temperature; eg. 72°F in Orlando). This free cooling
is worth up to half a ton of air conditioning during early summer.
And it can be a godsend when there is no air conditioning after
Even more importantly, research, including that by Subrato Chandra
at FSEC, has shown that carpeted floors can provide an excellent
breeding ground for dust mites in Florida homes– a well
known source of allergens for many people.
All these factors suggest that replacing much of your moisture-damaged
carpeted floors with tile will provide some help with cooling,
comfort and maintaining a more allergy-free home. Confine carpet
to bedrooms only or consider the use of throw rugs.
Although many homeowners will be interested in accomplishing
the repairs and replacements to their homes as soon as possible,
they would do well to consider the long-term benefits of making
energy-efficient choices as they make those repairs.
|The Disaster Contractors Network web site (www.dcnonline.org)
has detailed information on roof repairs, model contracts,
emergency loans and even a list of licensed Florida contractors.
Visit this web site for a great deal of important information
that can help you rebuild after a hurricane or other disaster.
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Solar Energy Center, Cocoa, FL.
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