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Definition

Securing loose items is one of the most basic and easy precautions to take in the event of a forecast calamitous event. Items to be secured can either be integral to the building (such as roofs and mechanical equipment) or extraneous to the building (such as compressed gas cylinders and scaffolding).


Issues Addressed

Wind exerts forces on everything in its path. The following are some of the most common situations[1] :
An example of roof hurricane cliips.  Source: Insurance Institute for Business & Home Safety
An example of roof hurricane cliips. Source: Insurance Institute for Business & Home Safety

Wind Speed & Force

Any integral building part and scaffolds that are susceptible to wind must be engineered to withstand the force of that wind, accomplished through additional ties, guys, counterweights, and/or bracing.

Suction

The force of wind on one side of an object conversely causes negative pressure on the opposite side. This negative pressure can lead to "suction." The engineer must therefore design for tension loads in addition to compression loads where applicable.

Uplift

In much the same way that air moving across an airplane wing causes lift, wind moving across stationary flat objects on a site (such as scaffold planks) can cause these objects to become airborne if not properly secured. Window and door openings can also be susceptible to blowing out from uplift forces.

Enclosed Scaffold

Many times scaffolds are enclosed to prevent falling debris and to enclose a heat source during the winter months. Unfortunately, this increases the risk of the enclosure acting like a huge sail. This type of scaffold must be tied more securely and frequently to prevent this issue.

Sidewalk Bridge Decking

This decking has even stronger uplift forces, especially if outfitted with a parapet. Any canopied sidewalk bridge should be securely tied into building wall or guyed to resist the wind loads.

Suspended Scaffold

These are especially dangerous in windy conditions and might encounter unforeseen swirling winds. The best precaution in to lower the scaffold to the ground before such a wind event.

Compressed Gas Cylinders

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Typical CMU detail. Source: FEMA

While OSHA already has strict regulations regarding the use and storage of compressed gas, it is doubly important to ensure that the regulations are being followed. Cylinders must preferably be stored in locked cages, and if not, they must at least be securely chained to a part of the building structure. Cylinders are under pressure, and can easily become missile-like projectiles if put under undue stress.

Nailed Connections

A simple "toenailed" joint on a roof or wall is not sufficient. These joints must have hurricane clips installed.


Considerations
Securing loose items is not an optional practice, nor is it an especially complicated one. Building components and scaffolding may require engineering calculations, but these should already be part of the scope of work in the first place. External items require just some forethought and weather forecasting.


Applications

Securing loose items is applicable to nearly every building, but it is even more of an issue at active construction and industrial sites where large loose materials and building components may be present.


Related Reports

Safety Issues: Wind
Insurance Institute for Business & Home Safety

http://emergencymanagement.wi.gov/mitigation/docs/1432_final_report.pdf


References


  1. ^


    "Safety Issues: Wind." Safety from the Ground Up 900.10 (2010): n. pag. Scaffolding and Access Solutions. Safway Services, LLC, June 2010. Web.