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]

Can Lead At Work Harm My Child

Can Lead at work harm my child? Yes. Your child can get lead poisoning if you or someone who lives in your home works with lead. Some kinds of work make lead dust or fumes. You cannot see lead dust, but it can get on your hands, face, and clothes. You take lead dust from your job to your family when  read more..

Methamphetamine Cleanup

Each week an average of 300 unlawful methamphetamine laboratories are found across the United States. After law enforcement intercede, a hazardous mess still remains. From cocaine to methamphetamine, each week an average of around 300 laboratories intended to make methamphetamines are found a  read more..

Emergency Board Up_Emergency Procedures For Storms

Levees & Dams- Levees are designed to protect hold back a certain level of water. However, levees can and do fail; and when they fail, they can fail catastrophically. Weakening of levees over time, or as a result of weather events exceeding the levee's level of support, can  read more..

Crime Scene Clean Up Certification

Respond with caution.Officers who arrive at a crime scene must be cautious and methodical. They should strive to preserve the scene with minimal contamination[opens in pop-up window]and should not disturb physical evidence. The responding officer(s) should: Note or log dispatch information (e.g., ad  read more..

How To Get Rid Of Crawl Space Mold

In time,shingles deteriorate from weathering, mechanical wear, and decay. Roof decay due to rain leaks and improper flashing sometimes is troublesome in sheathing and fascia boards. Leaks may also occur near the eaves from the water that backs up under melting snow, Crawl Space Drying How To Get Rid Of Crawl Space Mold unless flashing is  read more..

Get The Smell Of Raw Sewage Out Of The House

The overall performance of a lift station depends on the performance of the pumps. All pumps have four common performance characteristics: capacity,head, power, and overall efficiency. Capacity (flowrate) is the quantity of liquid pumped per unit of time, typically measured as gallons per minute(gpm  read more..

How Do Whole House Dehumidifiers Work

This study will determine the feasibility and effectiveness of the motion and collection of water molecules and droplets when influenced by a strong electric field and corona discharge. An innovative way of developing a high electric field with air moving past the field will be examined and tested.   read more..

How To Hide An Aluminum Sliding Window With Wood

Drain deaerator and open inspection doors and trays. Drain all boiler feed pumps and lines.7. Drain condensate receiver tank. Open manhole on tank.8. Drain chemical feed pump barrels and dispose of chemicals in a safe manner.9. Drain water softener tank and brine receiver.10. Shut off valves to main  read more..

Leaking Toilet Base

Burst Pipe Floods Basement Areas On the front page...Late Tuesday evening, June 26, the Clinical Center experienced one of the worst floods in its history when a water booster pump vibration eliminator on a chilled- water pipe burst and ran for 40 minutes before it was detected Water Damage Leaking Toilet Base and st  read more..

Crime Scene Clean Up Technician Training

Evidence recovery and interpretation at the crime scene is the essential first step in forensic investigations. Several organizational approaches to crime scene investigation and subsequent forensic laboratory activity exist,  Crime Scene Cleanup Crime Scene Clean Up Technician Training  sometimes involving a large number of personnel with vari  read more..