Wind Damage >> Hurricane Protection Techniques

 For other basic wind speeds, or for an importance factor of 1, multiply the tabulated number of #12 screws by to determine the required number of #12 screws or (¼ pan-head screws) required for the desired basic wind speed, VD (mph) and Hurricane Protection Techniques importance factor, I.4. 

For other roof heights up to 200', multiply the tabulated number of #12 screws by (1.00 + 0.003 [h - 30]) to determine Hurricane Protection Techniques the required number of #12 screws or ¼ pan-head screws for buildings between 30' and 200'.

Example A: 24" x 24" exhaust fan screwed to curb (table row 7), Base Case conditions (see Note 1): 2.5 screws per side; therefore, Hurricane Protection Techniques round up and specify 3 screws per side.Example B: 24" x 24" exhaust fan screwed to curb (table row 7).

Base Case conditions, except 120 mph and importance factor of 1: 1202 x 1 902 x 1.15 = 1.55 x 2.5 screws per side = 3.86 screws per side; Hurricane Protection Techniques therefore, round up and specify 4 screws per side.Example C: 24" x 24" exhaust fan screwed to curb (table row 7).

Base Case conditions, except 150' roof height: 1.00 + 0.003 (150' - 30') = 1.00 + 0.36 = 1.36 x 2.5 screws per side = 3.4 screws per side; therefore, Hurricane Protection Techniques round down and specify 3 screws per side.* This factor only applies to the long sides. At the short sides, use the fastener spacing used at the long sides. 

Fan Cowling Attachment: Fans are frequently blown off their curbs because they are poorly attached. When fans are well attached, Hurricane Protection Techniques the cowlings frequently blow off (see Figure 3). Unless the fan manufacturer specifically engineered the cowling attachment to resist the design wind load, cable tie-downs (see Figure 4) are recommended to avoid cowling blow-off. 

For fan cowlings less than 4 feet in diameter, 1/8-inch diameter stainless steel cables are recommended. Figure 3 caption. Cowlings blew off two of the three fans shown in this photo. Cowlings can tear roof membranes and break glazing. [end of caption] Figure 4 caption. To overcome blow-off of the fan cowling, Hurricane Protection Techniques this cowling was attached to the curb with cables.  

For larger cowlings, use 3/16-inch diameter cables. When the basic wind speed is 120 mph or less, specify two cables. Where the basic wind speed is greater than 120 mph, Hurricane Protection Techniques specify four cables. To minimize leakage potential at the anchor point, it is recommended that the cables be adequately anchored to the equipment curb (rather than anchored to the roof deck). 

The attachment of the curb itself also needs to be designed and specified. Ductwork: To avoid wind and windborne debris damage to rooftop ductwork, Hurricane Protection Techniques it is recommended that ductwork not be installed on the roof (see Figure 5). If ductwork is installed on the roof, it is recommended that the gauge of the ducts and their attachment be sufficient to resist the design wind loads. 

Figure 5 caption. Two large openings remained (circled area and inset to the right) after the ductwork on this Hurricane Protection Techniques roof blew away. [end of caption] Condensers: In lieu of placing rooftop-mounted condensers on wood sleepers resting on the roof (see Figure 6), it is recommended that condensers be anchored to equipment stands. 

(Note: the attachment of the stand to the roof deck also needs to be designed to resist the design loads.) In addition to anchoring the base of the condenser to the stand, Hurricane Protection Techniques two metal straps with two side-by-side #14 screws or bolts at each strap end are recommended (see Figure 7). Figure 6 caption. Sleeper-mounted condensers displaced by high winds.  

Figure 7 caption. This condenser had supplemental securement straps (see arrows). Two side-by-side screws with the proper edge and Hurricane Protection Techniques end distances are recommended at the end of the strap. [end of caption] Vibration Isolators: 

When equipment is mounted on vibration isolators, an isolator that has sufficient resistance to meet the design uplift loads should be specified and installed, or Hurricane Protection Techniques an alternative means to accommodate uplift resistance should be provided (see Figure 8). Figure 8 caption. 

The equipment on this stand was resting on vibration isolators that provided lateral resistance Hurricane Protection Techniques but no uplift resistance (above). A damaged vibration isolator is shown in the inset (left). [end of caption] Access Panel Attachment: Access panels frequently blow off. 

To minimize blow-off of access panels, job-site modification will typically be necessary (for example, the attachment of hasps and locking devices such as a carabiner). The modification details will need to be tailored for the equipment, Hurricane Protection Techniques which may necessitate detail design after the equipment has been delivered to the job site. 

Modification details should be approved by the equipment manufacturer. Equipment Screens: Equipment screens around rooftop equipment are frequently blown away (see Figure 9). Equipment screens should be designed to resist the wind loads derived from ASCE 7. Note: The extent that screens may reduce or Hurricane Protection Techniques increase wind loads on equipment is unknown. 

Therefore, Hurricane Protection Techniques the equipment behind screens should be designed to resist the loads previously noted. Figure 9 caption. Several of the equipment screen panels were blown away. Loose panels can break glazing and puncture roof membranes. 

Other resources: Three publications pertaining to seismic restraint of equipment provide general information on fasteners and Hurricane Protection Techniques edge distances: • Installing Seismic Restraints for Mechanical Equipment (FEMA 412) • Installing Seismic Restraints for Electrical Equipment (FEMA 413)• Installing Seismic Restraints for Duct and Pipe (FEMA 414).

Figure 7 caption: A failed prong-type splice connector. If conductors become detached from the roof, they are likely to pull from pronged splice Hurricane Protection Techniques connectors. [end of Figure 7 caption] Figure 8 caption: To avoid free ends of connectors being whipped around by wind, bolted splice connectors are recommended because they provide a more reliable connection.  

Strengthening Attachment of Existing Systems: On critically important buildings that use adhesively-attached connectors and pronged splice connectors,Hurricane Protection Techniques it is recommended that attachment modifications based on Construction Guidance be made in order to provide more reliable securement. [End of Recovery Advisory]

Water Damage

A dampness in your home is usually the result from a water incursion either from an internal source, like leaking water pipes or an external sources, such as rainwater due to some kind of storm damage. The intrusion of the dampness becomes a real problem when the various materials in your bui  read more..

Certified To Do Lead Removal

If you wish to become certified to do lead-related construction work in California, you must take training from one of the Department of Public Health's (CDPH) accredited training providers. To find out where you can take the this training, go to this link to see the list of approved lead-related co  read more..

How To Prevent Basement Condensation

Perlite is a mined volcanic glass material. When heated, water trapped in the glass matrix vaporizes. As it does so, it expands the heat-softened glass Basement Drying How To Prevent Basement Condensation material, creating a particle with a rough outer surface and an interior composed of closed-cell glass bubbles. He recommends use of this   read more..

Signs Of A Hoarder

In late December, Lake Johanna Fire Department responded to a fatal house fire in Shoreview. The Department's response efforts were complicated by the "hoarding situation found inside the home. The Fire Department, as well as City and County staff, Hoarding Signs Of A Hoarder have become more aware of these hoar  read more..

Risks Of Being A Crime Scene Clean Up Technician

Crime scene processing will begin after incident stabilization of the scene. Incident command priorities of life safety, search and rescue, and security precede crime scene preservation and processing. (05/15/96) Only the Watch Commander or Crime Scene Cleanup Risks Of Being A Crime Scene Clean Up Technician on-scene investigative supervisor can relinq  read more..

CONSTRUCTION BASICS OF A LEAD HEALTH

CONSTRUCTION BASICS OF A LEAD HEALTH & SAFETY PROGRAM All of the following protective measures areimportant for preventing work-related lead poisoning. Review each item and check the box if the statement is true for your workplace. Unchecked boxes may indicate problems that should be corrected,   read more..

Water Damage Guitar Restoration Tips

For detailed instructions on PEM requirements and test procedures, including screening, qualification, DPA test procedure, additional evaluation analysis, derating, and handling and storage guidelines refer to Instructions for PEM Selection, Screening,  Electronic Restoration Water Damage Guitar Restoration Tips and Qualification, PEM- IN  read more..

Where Does Radon Come From

Health effects observed in animals exposed to radon and radon decay products include lung carcinomas, pulmonary fibrosis, emphysema, and a shortening of life-span (U.S. DOE/Office of Energy Research 1988a). The incidence of respiratory tract tumors increased with an increase in cumulative exposure   read more..

Types Of Security For Fenced Yards

Storm surge levels on Galveston Island and on the west side of Galveston Bay are estimated to be between 10 and 15 ft. Here, too, several NOS tide gauges failed, although the gauge at Eagle Point on the west side of Galveston Bay recorded a maximum surge of 11.48 ft.The highest inundation, of at lea  read more..

The Effects Meth Labs Have On Wildlife And Vegetat

In addition to the General Cleanup Requirements in Section B, at aminimum a typical cleanup for a Tier 2 Response shall Meth Lab Cleanup The Effects Meth Labs Have On Wildlife And Vegetat include the following:1) Where applicable/appropriate, follow all cleaning procedures described in Tier 1.2) This Tier differs from Tier 1 Responses in that additional af  read more..