Flat gable bottom and scissor truss

[Daniel Ozarks]

I have a similar situation to what's been discussed in the past - flat bottom gable truss with a scissor truss next. My question is, how come a solution isnt just running some 1 inch steel pipe from the floor, through the top plate, and up to the top of the gable? 2 should be fine but you could do as many as you want.

 

[mike93lx]

You shouldn't add random bracing to a truss. Needs to be designed for the load.

If an engineer signs off on that fix, then go for it, otherwise I wouldn't have confidence that it would be shifting a failure point to another place

 

[Daniel Ozarks]

The "engineered" recommendation is single toothpick studs from top to bottom which has its own challenges. All trusses need braced, but in the case of flat bottom to scissor the question is how to do it to eliminate the hinge. All that a 1 inch steel pipe does is connect the gable and the wall making it all one piece. Drilling 1 inch holes in the top plate isnt a problem so I'm just wondering why this fix isnt being recommended. Either no one thought of it or perhaps it's too easy since man likes to take simple things and complicate them.

 

[wssix99]

The framing needs to act as a beam against the wind. A steel pipe would not be a good choice for this application. In addition to steel pipe not being designed/tested/rated for structural uses, pipes are generally bendy. If you take a quality 2X4 and a steel pipe of a similar depth and make bridge out of them, you should find the wood bends less. (In real life, such an experiment would take a lot of lateral bracing for the 2X4, like it has in a wall, to see the results.)

 

[Youngandfree]

I have a similar situation to what's been discussed in the past - flat bottom gable truss with a scissor truss next. My question is, how come a solution isnt just running some 1 inch steel pipe from the floor, through the top plate, and up to the top of the gable? 2 should be fine but you could do as many as you want.

What's the problem your looking to correct?

 

[mike93lx]

The "engineered" recommendation is single toothpick studs from top to bottom which has its own challenges. All trusses need braced, but in the case of flat bottom to scissor the question is how to do it to eliminate the hinge. All that a 1 inch steel pipe does is connect the gable and the wall making it all one piece. Drilling 1 inch holes in the top plate isnt a problem so I'm just wondering why this fix isnt being recommended. Either no one thought of it or perhaps it's too easy since man likes to take simple things and complicate them.

You call it a fix, but I challenge that assumption.

Run it by your engineer

 

[The Tool Tyrant]

The best answer is to frame your wall as a rake wall (match the bottom chord of your scissor truss) and have 'gable fill' added to the scissor placed on the wall. This eliminates the hinge once you run your catwalks through.

 

[Daniel Ozarks]

The framing needs to act as a beam against the wind. A steel pipe would not be a good choice for this application. In addition to steel pipe not being designed/tested/rated for structural uses, pipes are generally bendy. If you take a quality 2X4 and a steel pipe of a similar depth and make bridge out of them, you should find the wood bends less. (In real life, such an experiment would take a lot of lateral bracing for the 2X4, like it has in a wall, to see the results.)

Thank you for your reply. I can see what you're saying. The pipe thickness would have to be considered.

When I've read about this elsewhere people talk about how the OSB and drywall will stiffen the hinge or other such little things to help because these hinges are apparently common and there are probably a large number of homes out there with them that just never have issues. Some do and that's why the discussion and others recognize the issue during construction and seek to handle it in some way. So when there's talk about glued wood chips and rock dust as "helping" then I'm like why the heck not some steel pipe then since we're talking about redneckin' things. I'm not against redneckin' and many times these ways are superior to the ways of the proud engineers who have a bought piece of paper that says they are all supposedly smart where many of the houses they engineer fall apart.

So anyway, in my situation, as like many others, my structure is not on the beach in Florida and subject to a bunch codes and whatnot. We are just looking for something that will work in reality no matter how unconventional. I am also able to run some 14ft supports to the next wall if necessary. Either 1 or 2 beams, which may be too heavy, or 2x's and then box around them with wood or drywall.

 

[kbs2244]

The best answer is to frame your wall as a rake wall (match the bottom chord of your scissor truss) and have 'gable fill' added to the scissor placed on the wall. This eliminates the hinge once you run your catwalks through.
^^^^^^this
the gable needs studs to nail the sheathing to
j

 

[Zeke]

I don't see how anyone can post an answer. I can't see in the question where a wall is mentioned. Like @Youngandfree asked, what is the problem?

 

[nmk_61802]

Either no one thought of it or perhaps it's too easy since man likes to take simple things and complicate them.

Seems to me you are the one making things more complicated. Ballon framing is a common fix. No real engineering required. Lumber is common, inexpensive and available. Can be nailed to the adjacent studs and sheeting, increasing is effectiveness.

As you indicated, any properly sized material could do the job, but why reinvent something that is already so simple.

 

[The Tool Tyrant]

I don't see how anyone can post an answer. I can't see in the question where a wall is mentioned. Like @Youngandfree asked, what is the problem?

Got to read between the lines...he mentions "top plates", so you have to assume 'wall'. So I assume he framed the gable end wall level instead of as a rake wall, so he ends up with a level hinge point at the top plate/ gable truss bottom chord point. He wants to run the pipe to make a 'strong back'...kinda. It's the MacGyver approach!