Ladder Framing for Roof Outriggers 1

[reverbz]

Hey Guys,

I'm trying to frame some outriggers in a wood residential building. See below for what I've initially drawn trying to use a ladder framing approach. the light blue are typ. TJI's. The red are beams and the green are where I can locate posts. There are openings below these beams so there's no wall or posts that can be added. I think the main issue I'm running into is framing the corners of the outriggers. I end up with 2 cantilevered beams and I'm trying to think how we can get around that. Do you guys think my drawing looks reasonable? Should I just have them do steel beams instead even though this is residential? Do you have any ideas on the corners?

Thank you!

 

[dik]

Similar to the framing on the left side. The corners are picked up by the cantilever beams on the sides.

 

[RontheRedneck]

Run outriggers at the corners at roughly a 45° angle.

 

[reverbz]

@dik @RontheRedneck the problem I'm seeing is that my beams are essentially cantilevers going to the corner on each side. I need them to be supported at 2 points. and as of now they're only supported at 1. I've attached another image where I've circled the area I'm wondering about. What does this connection look like so that the beam is supported at 2 points if it's wood?

 

[jayrod12]

If this must be wood, you need more columns/supports. I understand the desire for minimizing them etc. But the final layout can't defy gravity. Work with your architect/desirgner and find somewhere to put a column near that inside (thick red line) corner and then cantilever some framing out to the corner.

 

[phamENG]

Those side overhangs are what? a foot? Cantilever the rim members to pick up the corner. That's how these are typically framed, and they 'work'. Proving that reality isn't very hard, though to meet code some of the connections have to be beefed up a little.

 

[reverbz]

@phamENG the problem is I'd need 2 support points for the rim beams. I don't see how I can do that unless there's a way to do a connection where I circled.

 

[phamENG]

You have lots of supports at each of the overhangs from the rafters that are cantilevered along that wall. Obviously some of the values of these reaction vectors will be negative...

 

[reverbz]

@phamENG If the rafters are supporting the rim beams they're just cantilevered though right? I'm not familiar with how to make that work with wood rafters

 

[phamENG]

material doesn't matter (at least not until you start detail and selecting sizes). Cantilever your overhangs wherever you can. You'll have the primary framing direction - that's easy. extend the rafters out to form the overhang. in the other direction, come in whatever distance you need and turn framing toward that wall and cantilever those to form the overhang in that direction. Then use the rims in each direction to cantilever off of the overhangs and meet at the ends.

Now, if you don't have any walls below because windows go right up to the ceiling/soffit and they're trying to make a wood building look like a concrete building...tell them to add a column or let you design with steel and concrete.

 

[dik]