This involves the location, style and strength of connections from the awning or canopy to the building or to its foundation. Proper design of this element assumes recognition of the amount of force occurring, and the direction in which this force acts, at the connection at the time that the maximum design load occurs on the frame. Most common types of connections involve expansion anchors, wood lag screws and adhesive anchors.
Expansion anchors are used to fasten awnings to concrete surfaces. They develop their essential strength by pressing hard against the side of the drilled hole in which they are set. This pressure results in high frictional resistance to pull out. While these kinds of anchors have been successfully used for a long period and may be well manufactured, their use requires good judgment. When fastening to concrete surfaces, expansion anchors may be the only practical choice.
- Wood lag screws are tapered to a point and do not utilize nuts. These are not as sound as bolt through connections because they are subject to pulling out as the wood surrounding the threads crumbles or chips. Their strength, then, is proportional to the hardness of the wood in which they are embedded. In many awning applications that require fastening to wood framing, other connections are not possible and wood lag screws may be the best available option
- Bolt Through connections are preferable, when they are feasible, because the bolt and the nut are manufactured to controlled specifications, and there is a wealth of data on the strength provided by such a connection.
- Adhesive anchors have been made available in recent years to provide the awning installer a way to address field situations in which the preceding anchor types are not suitable. Examples of such conditions are veneer brick surfaces and fasteners located close to corners, where the high pressures associated with expansion anchors directly to the substrate by filling an oversized drilled hole, which contains the threaded fastener, with an epoxy adhesive. This system does not rely on pressure.
When anchoring awnings and canopies, the awning contractor is often attaching to existing structures (buildings, walls, roof, foundations, slab, etc.).
* All about fabrics- A Guide for city officials architects and design professionals, by Professional Awning Manufacturers Associations, a division of IFAI.
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