Residential Deck - Big Cantilever 2

[JungleJoe]

Hi everyone, thanks for reading.

I am working on a residential project that has a deck with big (7' long) cantilever past the deck beam. The owner would like to use wood everywhere on this. See the pics below. Is there anything wrong with designing the deck joists to cantilever out that full distance? I've never designed a deck with a cantilever bigger than about 2' so going out just over 7' makes me nervous. I have run some numbers on some I-joists that seem adequate to me, but I'm wondering if any of you has experience with a cantilever like this. I will make sure to design the connection of the joists at the ledger. What potential issues have I neglected?

 

[JungleJoe]

phamENG,

So the point load creates a moment, but a force couple (the thrust at the top and the bottom of the brace) counteracts the moment

Thanks for the detail, dik

 

[phamENG]

So the point load creates a moment, but a force couple (the thrust at the top and the bottom of the brace) counteracts the moment

Yep

 

[dik]

Just a thought... if you are using the side members for strength with a diagonal brace, and have a beam at the end of the cantilever, you no longer have a cantilever and can likely use 2x6 lumber... else, ignore the side members and diagonal brace completely...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[JungleJoe]

Thanks everyone for your help. I'm thinking I'll go with the idea of cantilevering side beams (using the angled brace) and also having a beam at the edge of the deck. The deck joists will hang into this beam which then has to hang into the side beams. Any recommendations for the connection of the angled braces to the column? Would some lag screws through the angle into the column be sufficient or should I have through bolts that go all the way through the column? I haven't calculated the reactions yet but they won't be too big

 

[phamENG]

JungleJoe - I'd use the connection dik linked to above. Don't try to rely on the bolts. The connection will end up sloppy and probably not work very well. You need bearing in the post as the primary load transfer, and you can use bolts to hold it tight.