Or someone else with truss knowledge…
I’m trying to find a link to some information by a truss manufacturer or perhaps an engineer on why you don’t cut truss members that I can send to my brother so he can read it for himself.
He wants to put in an attic pulldown stair unit and the jackleg hack that he called is telling him that there’s nothing wrong with cutting the bottom chords and running the stair unit perpendicular to the trusses.
I told him to RUN! don’t walk away from this idiot, but he’s not going to believe anything I tell him about how cutting a truss member will screw up the integrity of the truss. “they’re just 2x4s what could it hurt?” He is going to want to see something “official” by an “expert”
Help me save him from his own ignorance before it’s too late.
Replies
I did a thread once called Cutting trusses for skylights that covers this, and explains "why" to some degree.
I don't recall anything "official" that's published by the WTCA or someone like that. If I come up with something I'll let ya know.
Thanks Boss, good read there, at least it's something" If I were a carpenter"
I know it's been a couple of days since we last discussed this, but I did come up with something "official".I attached a PDF of a page from BSCI 1-03 - "Building Component Safety Information". It was put out by the WTCA and TPI. I talks about not cutting, drilling, or altering trusses. If you want to downoad the entire 4.5 Meg document, you can find it here:http://www.sbcindustry.com/docs/06_BCSI_booklet_FINAL.pdf.If that direct link doesn't work for ya, you can try here:
http://www.sbcindustry.com/bcsi.php
I would rather have one rose and a kind word when I'm here than a truck load when I'm gone
Thanks Boss. That's exactly what I had in mind!
A few days ago, in an e-mail I got from my brother, a little bit of light was shed on the "carpenter's" (and I use the term loosely) nonchalance regarding cutting truss members. I'll just cut and paste a sentence from Lil' bro's e-mail:
One thing that I forgot to mention is that this guy said that he was surprised our joists/trusses were spaced at 24 inches apart, rather than 16 inches apart in the attic, for a larger house. Anything to that? He also mentioned that he was surprised they only used 2x4s for the trusses, not 2x6 sections.
RED FLAG!!!!!!
Ok, so this guy quite obviously had never seen trusses before. didn't know that there was even such a thing as something other than rafters and joists. Now, I have worked with Carpenters (mostly in Texas) who did not care for trusses. They had a personal preference for rafters, feeling that their way of doing it was better. I'm not saying these guys were right or wrong, personal preference is a perfectly acceptable reason for doing anything one way vs. another. And they do just fine building houses the way they prefer, with rafters instead of trusses. To the best of my recollection none of the roofs that these guys have framed have fallen down yet. :-)
But at least all of those guys knew what trusses are!!!!
To be in this industry in any capacity, passing yourself off as a knowledgeble, capable carpenter and never have been exposed to trusses is awfully scarey in my opinion. It makes me wonder what other commonplace everyday materials and techniques this guy has never seen.
"Well sir, I started working on fixing the hole in your plaster and I'll be darned if I didn't discover that it's only about a half an inch thick... and it seems to have paper on the inside, and the outside as well.... strangest plaster I've ever seen!!!
Ignorance is one thing, and is certainly forgivable. Passing one's self off as a pro and being that ignorant is another thing altogether.
By the way, the guy was young, way too young to have been alive back when there were only rafters." If I were a carpenter"
One thing that I forgot to mention is that this guy said that he was surprised our joists/trusses were spaced at 24 inches apart, rather than 16 inches apart in the attic, for a larger house. Anything to that? He also mentioned that he was surprised they only used 2x4s for the trusses, not 2x6 sections.
Mark,
Trusses can, in fact, have 2x6 members (see: http://www.alpeng.com/upload/19268/RoofSpan.pdf for examples). Also, rafters are commonly laid out at 24" o.c.. The point is that neither chord size nor spacing can be used as a single criterion to determine whether a system is rafter- or truss-based.
I'm not saying this "carpenter" is not an idiot, but I think its a non sequitur to conclude from the above email quote that he'd never seen a truss before. He probably has; he just utterly fails to understand how any structure works (be it a truss system or conventional rafters and ceiling joists).
Now with that said, I hope you get that idiot out of your brother's house. ;)
"...this guy said that he was surprised our joists/trusses were spaced at 24 inches apart, rather than 16 inches apart in the attic, for a larger house. Anything to that?"
Probably 99% of the trusses I do are 2' O.C. Can't speak for the entire country, but it's certainly the norm here.
"he was surprised they only used 2x4s for the trusses, not 2x6 sections."
We go to 2X6 mostly for handling. Once you start getting up around 45' or so, the strusses are pretty "stringy". You need the added lumber for handling as much as strength.
"To be in this industry in any capacity, passing yourself off as a knowledgeble, capable carpenter and never have been exposed to trusses is awfully scarey in my opinion."
I don't know that I agree. I've been around a long time too, but certainly don't have experience with everything.
I Base My Fashion Taste On What Doesn't Itch
I've been around a long time too, but certainly don't have experience with everything.
If you had been around a long time, and had experience with everything, your name would be piffin.
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
You could spend hours trying to explain the rigidity of triangles to him, or just jump to a simple demonstration.
Have him bolt two 4-ft long 2x4s together at the top, with a single bolt. and run a small rope, about 7 feet long, between the two ends that aren't bolted.
Stand it up, and have him push down as hard as he can on the top (a push up position would be ideal). Now while he is pushing down on it, cut the string.
I thinks that; by the time he picks his stupid self off the floor, he will have an idea of what a tension member does.
p.s. I am an engineer.
That's a great suggestion, however part of my problem here is the fact that we live about 1,000 miles apart.
If I was closer to him I'd just drive over there and install the stupid thing for him.
(But not before trying your demonstration, it's be kind of fun to watch him take a tumble...we are brothers after all.)" If I were a carpenter"
"By the way, while it's okay to attach things to a truss, never cut into one — you could do some serious structural damage."
from -
http://www.thisoldhouse.com/toh/tvprograms/asktoh/qaarticle/0,16588,845054,00.html
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Taunton University of Knowledge FHB Campus at Breaktime.
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"... Do not alter, cut or remove any truss members or components, ..."
from -
http://www.google.com/url?sa=t&ct=res&cd=57&url=http%3A%2F%2Fwww.nuconsteel.com%2Fimages%2Fpdf%2Fnutruss_specdata.pdf&ei=KOZFRp2UNpyKjAGAtOE_&usg=AFrqEzfP7lpdKQvJwHwQ86TQ0esZKL826w&sig2=IVQbAWPtG0E81R6OgoS34g
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
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Excellence is its own reward!
" CUTTING TRUSSES
Question: Our home has 2x4 roof trusses spanning 25 ft. spaced 16 in. o.c. Currently there is limited attic storage on a plywood subfloor on the bottom chords, accessed via a small hatch in a closet. We would like to install a fold-down attic stair with a rough opening size of 25.5 in. x 54 in., with the long dimension perpendicular to the trusses.
This would mean cutting the bottom chords of three trusses to frame the opening. Is this possible? If so, would double framing to the bottom chords of the adjacent trusses in the first and fourth bays be adequate to header off the three cut bottom chords?
Answer: NEVER cut any structural member of a truss! Any field modification that involves the cutting, drilling, or relocation of any structural truss member or connector plate shall not be done without the approval of the truss manufacturer or a licensed design professional.
One question that should also be asked regards what you are planning on using the access for? Be aware that the trusses most likely were not designed to carry additional loads on the bottom chord, if you are planning to use the attic space for storage. If this is what you are planning, you would be well advised to contact the truss manufacturer as to the amount of load the trusses were designed to carry. "
from -
http://www.lbrspec.com/FAQs.shtml#TrussRepairsAndAlterations
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Taunton University of Knowledge FHB Campus at Breaktime.
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that's ridiculous
A truss works by distributing the loads through each member. A single 2x4 might not carry a load, but a series of them triangulated can transfer loads to their endpoints. Cutting one of them is like removing a member of a football team, and expecting the team to perform equally well.
And cutting the bottom chord is like removing the offensive line. Tell your brother those 2x4's are there for a good reason.
Why not have your brother just call a local truss company? They should set him straight in about 15 seconds.