PalmSHIELD | 150 MPH Wind-Compliant Screening
Throughout history, every major U.S. storm has left rooftop mounted screens severely damaged or completely torn off (in addition to exposing, damaging, or decimating mechanical equipment). The same applies to ground-level installations: if architectural screens cannot tolerate high winds, neither can the HVACs, generators, transformers, etc. they protect. Inclement weather is something we all must plan for—be it thunderstorms, high wind, etc. As it happens, the architectural community has thought ahead and started categorizing entire sites (including site amenities) as projects that must comply with ASCE (American Society of Civil Engineers) safety requirements. After all, total safety means assurance that non-habitable structures don’t endanger personnel or nearby structures. For this reason, architectural screening must meet—if not exceed—ASCE standards, including standards regarding wind loads.
PalmSHIELD, the nation’s top architectural screening contractor, has achieved this! In the past, our products have met the standard wind load minimum (120 mph) defined by UBC (Uniform Building Code) and IBC (International Building Code). However, with wind speeds exceeding 120 on the record, we now offer a 150 mph-compliant option for our Atlas horizontal louver system! In this blog post, we’ll talk about what goes into creating 150 mph-compliant screening.
What questions must screening contractors ask when designing for wind loads?
- How can I determine the ASCE wind speed requirement for my project? Fortunately, the ASCE has defined standards for building and structural wind loads. Also, the ASCE’s wind speed maps help designers select proper wind speed delineation zones. Some states like Florida provide a listing of wind speed maps by county. For additional requirements regarding your individual project, contact your local building official.
- What is the difference between wind speed and wind pressure? Wind speed is the velocity of air movement, measured in miles per hour (mph). Wind pressure is the wind force exerted upon a structure and is measured in pounds per square foot (psf). Please note that wind speed does not determine wind pressure. In point of fact, wind speed’s merely a variable used to calculate wind pressure.
- What are exposure categories? An exposure category (B, C, or D) is a condition used to calculate wind pressures for a structure or building. Read on to learn about the three categories and what each of them signifies.
What do the three exposure categories represent?
These are the definitions, per Law Insider.
- Exposure B, the most common of the three, applies to urban, suburban, and wooded areas, as well as all terrains featuring multiple closely spaced structures with the same dwellings (single-family or larger). Exposure B’s usually classified for sites in residential subdivisions.
- Exposure C applies to open terrain with scattered structures less than 30 feet high. and extending more than 1,500 feet from the building site. Exposure C includes flat open country, grasslands, and shorelines in hurricane-prone regions.
- Exposure D applies to flat, unobstructed areas permitting wind flow across open water (excluding shorelines in hurricane-prone regions) one mile or more. Exposure D includes shorelines in inland waterways, the Great Lakes, coastal areas of California, Oregon, Washington, and Alaska. Exposure D extends from the shoreline a distance of 1,500 feet or 10 times the height of the building or structure (whichever condition is greater).
What are building risk categories?
- Risk Category I buildings have few to no human occupants or are temporary structures less frequently exposed to weather phenomena such as high winds.
- Risk Category II buildings tend to be small and rarely house regular occupants.
- Risk Category III buildings are larger than Risk Category II structures and house a relatively large number of occupants.
- Risk Category IV buildings are those in continuous use, such as hospitals and police stations.
How do PalmSHIELD’s 150mph-compliant screens appropriate all of the above?
Our designers team up with licensed structural engineers to provide screening in compliance with the design criteria below:
V = 150 mph G = .85
Exposure C Kz = .85
Risk Category III Kd = .85
MWFRS Open Sign Structure Case A = 51.3 psf LRFD
If you determine your site meets the above exposure and risk category criteria, please communicate this to our estimating and design teams. They’ll work with you to assure your selected screening complies with ASCE wind load requirements.
Important note: all wind load compliances will be stated on system proposals and design drawings. If said data’s not in the documents, your screening system might not be compliant.
If you require site-specific engineered drawings stamped by an engineer licensed in your jurisdiction, please notify PalmSHIELD. We’ll collaborate with engineers local to your area to achieve these drawings. Engineered stamped drawings are not included in our proposals unless specifically requested.
If you want architectural screening to help protect site amenities from high-speed wind threats, contact our sales team today!