I have been following the thread on gusset plates (both conventional and non conventional) and I felt it was a good time to bring up another line along the hanger system.



Joist hangers are used in building construction to add structural integrity to a unsupported floor. These hangers are fastened with joist hanger nails which are about an inch and a quarter long (smooth bore) In a fire scenerio, joist hangers do heat up. If the hangers have been in use for over 5 years, there is a high probability if they used joist hanger nails that the nails are beginning to loosten up. Add water from supression and the heavy weights of the household possesions and you have a recipe for disaster.

I have operated on a fire scene where decks have collapsed due to weight and stress on the hangers. The smooth bore nails have little to no affect in keeping the hanger in place and the framing member falls.



In this photo make note of the joist hangers still attached to the wall of the house the deck was attached to and the missing ones (presumed attached to the framing member still) This was a NON fire situation.

They have many grades of hangers, most used in residential are medium grade. (cheaper)

Here is the site on the major hanger fabricator in America and the most common hanger and applications.

http://www.strongtie.com/products/categories/joist-hangers_diy.html

These hangers are also imperrative in the installation of TGI's. (wooden I-beams)

Have you seen these become an issue, and if so please share. I am hoping that with some extra effort to get the building code to mandate top flanges for better and longer lasting strength to avoid issues. This is important for just about every house thats been built or renovated since the year 1998 has them