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]

How To Clean Sewer Overflows In Your House

Do you have a chronic sanitary sewer backup problem? The City of Decatur has a program to help stop sewer backups in your home. The Sewage Cleanup How To Clean Sewer Overflows In Your House program is available to homeowners within the City of Decatur city limits. This brochure gives overview of the "Sanitary Sewer Backup Prevention Program"  read more..

How To Clean Up Smoke Damage To Drywall

Smoke Production and Transport Butler and Mulholland give a very good synopsis of the generation and transport of smoke components [112]. They present the current state of knowledge about smoke aerosol phenomena that affect smoke toxicity: soot generation, fractal structure of soot, agglomerate tran  read more..

Tenant Screening

If the tenant decides to move during the term of the lease, the tenant is usually still responsible for therent for the rest of the lease period, unless the dwelling can be rerented earlier. The landlord isresponsible to make a good faith effort to re-rent the property, and may not charge the origin  read more..

Radon Transform

RADON TRANSFORM MITIGATION STANDARDS 1.0 BACKGROUND The 1988 Indoor Radon transform Abatement Act (IRAA) required the Environmental Protection Agency (EPA) to develop a voluntary program to evaluate and provide information on contractors who offer radon transform Radon Mitigation Radon Transform control services to h  read more..

The Hazards Of Dealing With Lead Paint

Lead accumulates in the body following exposure. Lead stays in the blood for several months, and it can be stored in the bone for many decades. Lead poisoning (plumbism) usually results from many small exposures over a period of weeks or years. The brain and nervous system are particularly Lead Paint Removal The Hazards Of Dealing With Lead Paint  read more..

How To Protect Fences From Intruders

Although Ike became extra tropical while moving northward over Arkansas, its remnants caused several deaths and produced significant wind damage across the Ohio Valley. At least 28 direct and Emergency Board up How To Protect Fences From Intruders indirect deaths were reported in Tennessee, Ohio, Indiana, Illinois, Missouri, Kentucky, Mich  read more..

Drying Equipment

FEMA Hurricane Katrina Recovery Advisories FEMA has prepared a series of Recovery Advisories that present guidance for design, construction, and restoration of buildings in areas subject to coastal flooding and high winds from Hurricane Katrina. To date, Structural Drying Drying Equipment eight advisories have been pre  read more..

How To Stop An Angry Tenant From Destroying Your P

The most common complaint received by the Montgomery County Office of Landlord-Tenant Affairs concerns deductions made by a landlord from a security deposit. This booklet provides landlords and tenants with guidelines and principles for fairly and accurately determining what constitutes ordinary wea  read more..

Physical Symptoms Of A Meth Lab In Your Apartment

CLEANUP PROCEDURES FOR SOIL, GROUNDWATER AND SURFACEWATER
If areas of soil, surface water or groundwater contamination Meth Lab Cleanup Physical Symptoms Of A Meth Lab In Your Apartment are present, characterizationand cleanup of these areas should be conducted by a professional environmentalcontractor, in consultation with the CT Department  read more..

How To Build In The Flood Plain

A damp basement can be a nightmare, especially after mildew creates its eye-watering, nose-offending stench. There are two enemies to overcome: damp air condensing on interior walls and ground water penetrating the exterior. One can address condensation by drying or Flood Damage How To Build In The Flood Plain heating the air in a basemen  read more..