StonePly & Wind Loads
Hurricane force winds are no match for Thin Stone Panels
- Tested to 300 mph wind speeds
- 400 lb per square foot wind loads
- Flying debris resistant (missile impact) . Test panels survived large missile impact (a 2" by 4" wood stud) fired at 50 ft. per second. The same test shatters normal 1 ˝" granite.
- The epoxy composite and adhesive technology used on aircraft flying at mach speeds.
Wind Loads
We've all seen the damage done by hurricanes, tropical storms, thunderstorms and high winds. Building owners, architects, builders, code officials and insurers are all aware of the need to build strong, wind resistant structures. We have a 25 year track record of successful composite installations, some of which have been through multiple hurricanes (including a category 5 hurricane) with no damage other than a few minor scratches from flying debris. Per the International Building Code wind speed map, the highest listed wind speed for all 50 states in the USA is 150 mph. For special applications, StonePly components have been designed and tested for wind speeds in excess of 300 mph. The main constraint for wind load resistance in StonePly cladding panels is usually the attachment to the structure. Attachment options include threaded inserts, z clips, screws, adhesives and rivets. StonePly and their engineers will be happy to work with you to design the system connection that meets your needs.
Problems with Solid Stone Slab Cladding and High Wind.
Damage in a hurricane is often caused by flying debris. For this reason Miami Dade and several other agencies require impact testing of certain architectural components. The most severe of these tests is the large missile test. A weighted 2x4 is fired at the test subject. Normal stone panels typically fail this test. In a hurricane, this means that the stone shatters and the fragments fall. Not only is there damage to the cladding, but there is the potential damage from falling and flying stone debris and the damage to the now exposed wall behind the stone.
The number of hurricanes expected to occur during a 100-year period based on historical data.
- Brown area, 20 to 40
- Gold area, 40 to 60
- Green area, more than 60
Source USGS
StonePly Solves the Wind Problem
StonePly, unlike solid stone, stands up the large missile impact test. With an impact resistance that is up to 60x greater than 1.5" granites, it holds up to flying debris and protects the building that it is cladding. During the large missile test, the 2x4 bounces off of the StonePly panel. The same projectile shatters 1 ˝" granite slabs. StonePly relies on aluminum honeycomb and aviation epoxy, both used as components of aircraft whose surfaces experience wind speeds of thousands of miles per hour for thousands of hours.
Building Codes
StonePly has proven itself, both in the testing lab and in the real world in Category 5 hurricanes. The International Building Code (IBC) has now been adopted in most areas of the United States. It sets up certain standards of wind resistance. All US building codes use the engineering standard published by the American Society of Civil Engineers, ASCE7 “Minimum Design Loads for Buildings and Other Structures” as the basis for wind load design and calculations.
Both the International Building Code and ASCE7 include a wind speed map. The wind speed map is based on data compiled by the National Weather Service (NWS) from information gathered at airfields around the United States.
Notes:
- Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10 m) above ground for Exposure C category.
- Linear interpolation between wind contours is permitted.
- Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
- Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind conditions.
Wind Speeds in other areas in mph (m/s) are: Hawaii 105 (47) Puerto Rico 145 (65) Guam 170 (76) Virgin Islands 145 (65) American Samoa 125 (56)
Wind Glossary
- International Building Code (IBC)
- A model building code developed by the International Code Council. Most of the U.S. has adopted this building code (some areas with minor, locally adopted variations). The wind load provisions in this code specifically calls out the use of ASCE7 in wind load calculations.
- ASCE7
- The American Society of Civil Engineers design standard: "Minimum Design Loads for Buildings and Other Structures". Section 6 deals with wind loads. ASCE7 is the basis for wind load calculations used by all major building codes. The wind loads calculated by ASCE7 are then used as the basis for the design of the StonePly connection details.
- Design Pressure
- The measurement of wind resistance in both positive and negative (suction) forces that a stone cladding panel must withstand. Design Pressures are usually expressed in both positive (PSF+) and negative (PSF-) values. Also known as design load.
- 3-Second Gust
- The National Weather Service measurement of wind speed. The data for this measurement is taken from measuring devices set 33' above the ground at airfields across the USA. This data is then compiled into wind maps found in both ASCE7 and the International Building Code. The wind speed maps are based on a yearly 2% probability of occurrence (50-year average peak wind).
- Safety Factor
- The margin of safety added to the calculations when designing for cladding panels or elements.
- Mean Roof Height
- MRH is the height above grade level of the midpoint of a roof. Mean Roof Height is used as part of design pressure calculations in both ASCE7 and the International Building Code, and is calculated by averaging the roof eave and ridge heights.
- Wind Velocity
- The actual measured speed of airflow, wind velocity is usually expressed in MPH.
- Wind Load
- Pressures placed on a structure or component during a severe weather event. Wind Load is both a positive and negative force depending on the direction of the wind in relation to the orientation of the structure. Stone cladding and stone panel components should be designed and anchored to withstand both the positive pressure, and the suction.
