Scissor truss question

[markomarko]

Regarding my scissor truss gable end engineering plans. Is my gable end scissor truss being delivered with a flat bottom piece of lumber on it? It’s being delivered Monday and I’m trying to wrap my head around it. I circled the piece in question.

 

[mike93lx]

There shouldn't be, AFAIK.

You may know this already, but you have to balloon frame that end wall. You can't do a flat top plate then use short studs to tie into the truss

Do this


Not this

There's a Better Way - Structural Building Components Association

Why flat-bottomed gable frames are not always the best solution

www.sbcacomponents.com

 

[markomarko]

Yes that is what I’m expecting to do. I just wasn’t sure what that was on the engineering they sent me. It was throwing me off.

 

[mike93lx]

Yes that is what I’m expecting to do. I just wasn’t sure what that was on the engineering they sent me. It was throwing me off.

It doesn't have a call out for a part number, so I suspect it's there for dimensioning the width

 

[CraigStu]

Why would there be a scissor truss on the end wall. Seems like a standard truss matching the roof line and a standard wall would be a he11 of a lot easier.

 

[micromind]

I would specify basic gable trusses for the ends. No need to frame under them and the wall bears the load, not the truss.

 

[mike93lx]

Why would there be a scissor truss on the end wall. Seems like a standard truss matching the roof line and a standard wall would be a he11 of a lot easier.

That makes it hard to properly brace the trusses and tie in the ceiling. Check out the link I provided above.

The Gable framing needs to match the ceiling profile

 

[larry4406]

Hinge in the gable wall is best avoided....

 

[Firebrick43]

Why would there be a scissor truss on the end wall. Seems like a standard truss matching the roof line and a standard wall would be a he11 of a lot easier.

Because its against code in most places creating a failure hinge. This explains why

https://mitek-us.com/wp-content/uploads/uploadedFiles/_RedesignSite/Content/documents/engineering/tech-articles/design-tips/Gable%20End%20Hinge.pdf

 

[Bert_]

I would specify basic gable trusses for the ends. No need to frame under them and the wall bears the load, not the truss.

Sounds like a great idea, if you like a floppy weak wall.

 

[markomarko]

Another thing I just thought of. If I balloon frame, what’s keeping the exterior walls from kicking out since there’s no double top plate under the scissor truss?

 

[PCustoms]

Another thing I just thought of. If I balloon frame, what’s keeping the exterior walls from kicking out since there’s no double top plate under the scissor truss?

Huh?

Double top plate isn't about walls kicking out, it's about proper load transfer from roof to wall framing.

You have 8+ feet of 2x material continuously framed up and attached to the truss, which is tied back to the rest of the roof trusses. Why would the wall "kick out"?

 

[mike93lx]

Huh?

Double top plate isn't about walls kicking out, it's about proper load transfer from roof to wall framing.

You have 8' feet of 2x material continuously framed up and attached to the truss, which is tied back to the rest of the roof trusses. Why would the wall "kick out"?

And there is almost no downward load on that wall.

@markomarko it feels like you are getting way ahead of yourself on this build. You have trusses showing up but don't know how to frame the walls. How was the building designed?

 

[micromind]

Sounds like a great idea, if you like a floppy weak wall.

Once the plywood is on the outside and the 2X4 runners are installed on the trusses, it's actually a pretty solid wall.

 

[PCustoms]

And there is almost no downward load on that wall.

@markomarko it feels like you are getting way ahead of yourself on this build. You have trusses showing up but don't know how to frame the walls. How was the building designed?

His other thread

Thread 'Zip R6 on gable end with overhang' https://www.garagejournal.com/forum/threads/zip-r6-on-gable-end-with-overhang.559324/

 

[Firebrick43]

Another thing I just thought of. If I balloon frame, what’s keeping the exterior walls from kicking out since there’s no double top plate under the scissor truss?

The ceiling does or if no ceiling, the bottom chord bracing.

 

[CraigStu]

Because its against code in most places creating a failure hinge. This explains why

https://mitek-us.com/wp-content/uploads/uploadedFiles/_RedesignSite/Content/documents/engineering/tech-articles/design-tips/Gable%20End%20Hinge.pdf

Thanks Firebrick43.

 

[firebirdparts]

That’s not a truss pictured, so it’s very weak. That is why you need that brace.

Just to be clear, I am intending my response to be on topic. I am not making commentary on balloon framing but rather delivery