Drafting Service Files: A Short Guide to Wind Load and Why it’s Important for Glazing
There are many things to consider when deciding what type of architectural glazing to add to your building.
You need the chosen product to perform well aesthetically, and it also has to provide adequate light and heat control to the building interior. But these comfort and energy efficiency factors aren’t the only considerations.
Another, crucial factor is the wind load.
Wind load refers to the force exerted by the wind upon a building face. There are three types of wind load:
- Uplift wind load is an upward force that mostly impacts roofs and other horizontal structures like awnings and canopies. There are two competing forces at play: an upward force from wind flowing under the horizontal structure, and a downward force from wind flowing over it.
- Sheer wind load is a horizontal force applied to walls or other vertical structures, causing them to tilt or crack, and even causing the entire building to tilt in extreme cases.
- Lateral wind load is a horizontal force that can cause a building to move sideways from its foundation.
The wind load requirements of your design will depend on several factors. One of these factors is the project location. Design wind load requirements depend on the expected wind speed in the area.
But wind load requirements also depend on the surface area and shape of the building component in question (and of the overall building too). At minimum, all buildings must withstand a wind load of 500 Pa. But many buildings, especially coastal ones, will need to handle higher wind loads. Building height and local terrain features that could block or funnel wind pressure will also affect design wind load.
The ASCE 7, Minimum Design Loads for Buildings and Other Structures, defines various Exposure Categories based on the ‘surface roughness’ of an area. For example, Exposure B covers urban and suburban areas, wooded areas, or other terrain with closely spaced obstructions. Exposure C covers open terrain with obstructions that are scattered and less than 30 feet tall. And Exposure D covers structures within 600 feet from an open waterway that’s one mile or more across. Open exposures (C and D) require higher design wind loads than rough exposures (B).
When choosing a glazing product, you need to make sure it’s rated to handle your calculated wind load. System choice will depend on the loads it is required to withstand.
It’s important to note that wind load is just one piece of the glazing puzzle. Glass system projects are complex …
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