When Canopies Come Tumbling Down
Make sure your customers' older canopies can handle the elements.
By Joseph Langworthy
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| A canopy on the roof of a Marathon station
in Cleveland collapsed under the weight of snow in February.
A Cleveland city councilman plans to introduce legislation
requiring the canopies at gas stations, drive-throughs
and other businesses to have pitched roofs. |
|
In late February, weeks of arctic cold and persistent heavy lake
effect snow contributed to the collapse of two canopies in Cleveland,
Ohio. News reports attributed some of the possible reasons for the
collapse to unusually heavy snow and the fact that those canopies
were probably 30 years old and constructed to outdated building
codes.
During the last 20 years, building codes affecting canopy design
have been upgraded in some states along the hurricane-sensitive
Gulf Coast and the northern Snow Belt. As a result, canopies engineered
today are safer than ever. But what about canopies 20 or 30 years
old or older? Are these canopies worthy of service?
Canopy Maintenance
Four feet of snow, frozen clogged drains and gutters with a foot
of ice lying atop a canopy may exceed the original design criteria
for some canopies over 25 years old. This overloading causes unusual
stress and fatigue. While extra safety factors are built into the
structural steel frame, anomalous storms can possibly exceed any
structure's design parameters.
A canopy maintenance procedure can extend canopy life and enhance
the canopy's structural integrity during all types of weather. The
following are three strategies to keep older canopies worthy of
service, notably in climates with seasonal changes.
| 1. |
Add specialized canopy deck clips to reinforce
the connection between the deck and the structural steel framing
(particularly in older canopies). This process strengthens the
roof deck connection and allows the applied loads to be transferred
to the structural steel framing. This is important in heavy
snow areas. |
| 2. |
Clear gutters and deck of debris. In addition
to leaves and sediment, debris includes beverage containers,
cans, bottles, balls, food wrappers and bird nests. These items
may block the drains and cause several inches of water and eventually
ice to accumulate to form a mini swimming pool atop the canopy.
|
| 3. |
Perform an annual or biannual structural inspection.
In addition to cleaning the gutters, drains and canopy top,
conduct the following:
a. Check structural steel framing
for deformation and corrosion.
b. Verify that structural bolts
are tight. If corroded, replace.
c. Observe if fasteners
are broken or deteriorated. Replace as needed. |
Re-Image Materials
With the hectic pace of mergers and acquisitions, canopies are re-imaged
or re-branded to reflect the new owner or brand. Older canopies
may not have been designed to support heavier, more elaborate fascia
and signage. When a customer with an older canopy orders re-image
fascia and deck material, recommend that the customer have engineers
perform new structural calculations to be certain the canopy will
support the load of a brand re-image.
 |
| After a snow-laden roof collapsed at
this BP gas station in Cleveland, Ohio, injuring two people
and damaging four vehicles, BP temporarily closed 11 Cleveland-area
gas stations with canopies similar in age and style, so
workers could inspect each canopy and remove excess ice
and snow. |
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Except for major oil companies with significant experience maintaining
canopies, many jobbers are not aware a canopy may not structurally
support re-image materials during a brand change. You can beef up
a canopy by adding heavier steel, just like a home owner can improve
heating and cooling efficiency by adding insulation with a greater
“R” insulation factor. To minimize cost most buyers purchase
a canopy manufactured to, but not exceeding, the local code.
Up-to-Date Codes
Be aware that canopies constructed years ago are probably not up
to current code. Furthermore, most states follow the International
Building Code (IBC), and there are IBC code changes each year. Some
states are operating under the 2003 or 2004 IBC code. Many northern-climate
states, i.e., Ohio, Michigan, New Jersey, have adopted the 2006
IBC code as their standard. The 2006 standard increases the insulation
requirements, thus making commercial and residential structures
more energy efficient.
The canopy collapses this past winter heightened interest in gable
roof canopies. A gable roof canopy with a heavier structural steel
frame might make sense in heavy rain and snow areas. Regardless
of the type of canopy or the date of the code, following the three
maintenance recommendations above will benefit every canopy owner.
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