Joist seat extension capacities or load charts for larger seats?

[engreg]

Is there a load table for a joist seat larger the standard 2.5" joist seat. I am looking to extended a 5.5" joist seat around 10 or 11 feet. With the 2.5" values this seems very doable but I am not finding nay solid values on what the larger joist seats can span. Any info is helpful. Thanks

 

[BridgeSmith]

Not sure what you're designing here, but typically, the max spans are determined by the bending or shear capacity of the joists, and the minimum bearing seat width is what's necessary for the corresponding bearing load. In other words, increasing the bearing length doesn't typically (or ever, AFAIK) increase the allowable span.

 

[jayrod12]

Canam's catalogue has joist seat extension capacities for different seat depths.

 

[engreg]

I probably wasn't clear, I am trying to verify the cantilevered exertions will work on my roof joists. There is roughly an 11 foot overhang. The typical joist seat extensions give values up to 6 or 8'. But these are 2.5" joist seat extensions. A 5.5" should definitely be able to cantilever farther, but I cant find any charted data on it.

 

[engreg]

Similarly, if anyone knows of a chart for a reinforced top chords (4 angles instead of the standard 2). that would work, the Canam catalogue had higher values for higher shoe depths but nothing on larger top chords.

 

[jayrod12]

The Canam catalogue deeper shoe is talking about a larger top chord. If you look at their details, they show the top chord changing material for the last span plus the cantilever.

I've seen joist top chords made out of two C6 channels. So I'm sure if necessary they can do impressive things. I'm pretty sure if you ran the cantilever with something like C6 channels you could determine whether that will work for you or not.

 

[jerseyshore]

I've contacted Vulcraft many times over the years and they have always been helpful, supplying tons of tables that are not in the catalogs for various things. I'd say just reach out to a supplier first.