Can anyone tell me how to brace trusses. I have a gable roof. With a small attic space. Some one told me to put x braces every 20 feet along the trusses.(is this right?) The truss company won’t tell me how because they don’t want to be liable. Thanks Tim
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The truss company may not be willing to tell you, but they should have some literature for you to look over. (HIB-91 - Handling, Installation, and Bracing of wood trusses)
I tried, but have been unable to find an online version of the document. If they won't cough one up, email me your address and I'll mail you one.
Honestly - If you have no idea how to brace them - Are you sure you should tackle it? Unfortunately, I've been out on many jobsites where trusses fell over due to inadequate bracing. Some have involved serious injuries. I know of at least one person that has been killed by falling trusses.
Give some serious thought to getting some professional help.
BTW - How big are the trusses?
There's a bit of info here that might be helpful:
http://www.stuckeylbr.com/trusbraccon.html
Edited 7/13/2002 8:19:07 AM ET by Boss Hog
You are being asked to come to another post Boss . I think hes a nut . Line my wheels or something like that.
Tim Mooney
It's not unreasonable to expect the company that designed your trusses to provide the information that you need. The lateral bracing needed for each truss design is already considered in the engineering and accompanies the drawings that must go with the permitting process.
What isn't included is the calculations for wind loading which should be addressed by the engineer who stamps the overall project. Your local permitting or plan review official should be able to give you a handout that defines the bracing required by local code but many no longer provide that, because of liability, and REQUIRE an engineering stamp on a page or so of calculations and drawings, thus transfering liability for proper design and erection to an engineer and to the contractor who must follow the design parameters.
HIB-91 is a good reference publication but in the end, the engineer of record is responsible for the design and placement of necessary permanent bracing.
Ralph, GEOB21, and JASON_MI -
Truss bracing is divided into 2 issues - erection bracing and Permenant bracing. I think this guy was asking about erection bracing, which is why I referred him to HIB-91.
Calcs for wind loading may or may not have been done. It's largely ignored in many parts of the country. I probably don't design one truss in a thousand for wind loading.
The "engineer of record" is often a fictitional person, sometimes referred to as the "building designer". If this guy is just building a garage, he may not even need a building permit, much less an engineer or architect. So there may not be anyone to call out the erection or permanant bracing.
GEOB21 , you asked: "How can they supply a structural component with out instructions on how to properly install it?" A truss is generally considered to be just one piece of a building - Not a complete engineered system. Asking a truss company to call out erection bracing would be like asking the lumber company to call out your temporary wall bracing just because they sold you the studs and plates. So I doubt a lawyer would "have a field day with them" unless there was some local code requiring that.
HOWEVER - Things seem to be moving in that direction in general. Truss companies seem to be taking on more and more engineering responsibility. So that may someday be standard practice across the country. I hadn't heard that this was a requirement anywhere yet, but that appears to be what JASON_MI is saying is required in his area.
The following is a link to WTCA1-1995, "STANDARD RESPONSIBILITIES IN THE DESIGN PROCESS INVOLVING METAL PLATE CONNECTED WOOD TRUSSES" This document spells out general guidelines for design responsibilities regarding trusses.
http://www.woodtruss.com/images/publication_images/resp-d.pdf
Boss- I may be all wrong about this but the original post states putting an x brace every 20'. I assumed this was refering to permenant bracing because only bracing every 10th truss during construction is just nuts.
BTW a truss system roof is a complete engineered system and a 2x4 is raw material. A 2 x 4 can do many things but a truss has only 1 unique application. Might want to brush up on liability because if you design it and build it, it's yours.
Edited 7/13/2002 6:55:02 PM ET by GEOB21
By saying diagonal bracing every 20', I assume he means a diagonal brace every 20' to reinforce the bracing.
As for the liability thing - Did you read the publication I linked to? It was drafted by the Wood Truss Council of America, and went through a lengthy review process to eventually get adopted by ANSI. That takes precedence over your opinion, in my book.
Whan you say: "a truss system roof is a complete engineered system" that's not really true. Each one is an engineered component - They aren't designed as a system at all. Again, read the document from WTCA. That explains it quite well.
Geez Boss lets kick this one more time.
"Each one is an engineered component - They aren't designed as a system at all."
Trusses are designed with a special purpose. Each one is individually designed to work in conjunction with the others. Thats why it's important to set and brace them as they were designed. (I.E. 16" OC or 24" OC) That's what I mean by an engineered system.
"Trusses are designed with a special purpose."
Exactly - Each one is designed as an individual component.
"Each one is individually designed to work in conjunction with the others."
No they aren't. Each one is designed to work as an individual component. That particul truss is designed to carry a certain amount of weight. It doesn't care if there's one truss on each side of it, or 50 trusses. It's still designed to carry the same amount.
And each truss requires the same amount of erection and permenant bracing, regardless of how many trusses are on the building.
The building designer is the one who creates an "engineered system" by tying different parts of the building together.
x
Ok Boss man-
So lets say I have a building that must have 50 trusses. Now assuming your logic
I remove every other one because,
"It doesn't care if there's one truss on each side of it, or 50 trusses."
Does the building remain standing?
Answer....... NO! Because it was designed to have a truss next to it. It's design is based on the whole system.
I believe we are having "a failure to comunicate".
I'm done with this.
What has removing every other truss got to do with a "system"?
I don't think we have a failure to communicate - I just think you;'re the most hard headed SOB I've run across in a long time. I've tried to explain this over and over, but you just won't listen.
If you're done with this, so am I.
My wife keeps complaining I never listen to her...or something like that.
Boss, you are correct; the truss company is doing the engineering, with engineers (I hope to God), and are providing a truss plan/print detailing each type of truss. This goes with the plans to the planning/zoning office to get a permit, and they (inspectors), check that it has an engineers stamp, and the information contained on it conforms to the "basic" requirements of our area (snow load, wind, etc.). The inspectors also use these prints and physically check the permenant bracing.
Temporary bracing I am not familiar with (in terms of the publication)....and it is, to me, a common sense approach of using enough bracing to stablize the ongoing structure and ensure the structures' and peoples' protection throughout the erection process. The final result of the "system" of trusses is what's important. How you get there, via erection and bracing, is an individual building question, based on common sense, safety, and general knowledge, right?
"...the truss company is doing the engineering, with engineers (I hope to God)"
Engineers never see the vast majority of truss designs. I covered that in another thread, but can't recall which one.
There's more to the system than just trusses. The walls, bracing, and trusses are all part of the system.
If we are what we eat; I'm cheap, fast, and easy.
I have no doubt you're correct there, Boss. But every truss print we get has an Engineer's stamp on it...and that goes to the building department. I'm guessing it's really a case of CYA, all the way from the plant, through my hands, and to the inspector.
I think you should change truss supplier. Mine always supplies a bracing diagram I assumed it was part of the over all engineering of the truss system.
How can they supply a structural component with out instructions on how to properly install it? If anything they are liable for any failure what ever the cause.
A lawyer would have a field day with them .
When we order trusses, we get a diagram via fax within about 20 minutes that specifies OUR trusses and bracing. We can't get a permit, or a sign-off without it, and the first thing the inspector looks for is that diagram...with our jobname on it, when he comes out. What's up with your truss company, or with whomever sold them to you?
Gable wall.... two studs up, i.e. 4' down, well nailed, 4' sticking up,tack gable truss to that, install next two or three with blocking, then nail in your "x" you are talking about, onto one of the vertical members,taking care that they are plumb, in a straight line, etc. What you want to do is create a rigid assembly to install the rest from. A row or two of horizontal 2x4's on the top chord should keep them in a straight line,with layout marks paced out according to your plate layout, try to do that in greater than 4' increments,look at your permenent bracing schedule, you can put them in while your at it, if there is any.
no turn left unstoned
OK that is what I have been told. I will have a small attic space in it. Just for storage. To the top of my ridge is 15 feet. My walls are 9 feet. I was told two put the x brace starting at one gable end, and start at the top or the botom of the gable truss end. And place it at 45 degrees And nail 2 ,16 penny nails at each truss and the 2x4's are 20 feet. And with another 2x4 cross that one. And dothe same on the other end and the same on the other side. Thanks Hat
Around here they, the AHJ, demands that you run a 2by4 from the top of the gable at the ridge and lay it flat along the rafter, what would be the rafter if these weren't trusses, to the exterior wall. Fastened with 2-16d where the brace crosses each truss. The same pattern is repeated on the opposite side of the ridge for the same gable end. This is repeated, two braces per gable, at each gable end.
The idea,I have been told, is to create a triangular structure supporting the top of the gable end truss and the bottom cord of a truss at the top plate of walls. This bottom cord and the ceiling diaphragm contain the forces attempting to spread the walls apart.
In addition to this 2by4s at about 4' centers are run across the bottom cords of the trusses from the bottom of the gable end truss back for 8'. The first 2 trusses after the end truss are blocked between the flats of the trusses and the longer 2by4s nailed with 2-16ds at each truss. Please confirm these specs with your local code as these are from memory.
This procedure is designed to prevent the gable end collapses found in Homestead post Andrew. It was noted that these failures frequently caused complete loss of the house when the rain and wind penetrated the shell and the building blew apart.