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I hear ya about the roof collapsing JRS! Tore down a 50′ by 100′ riding arena last spring here in Michigan when the snow load caved the roof in. These trusses looked home made and were on 8′ centers! Still, it held up for about 25 years (found a date on one of the corner posts)
It collapsed in January-had a hell of a time getting everything out and using part of it as a run in shed until a new barn was built.
Spray foam is a great invention, but it's not always necessary.
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Replies
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A small suggestion: instead of nailing - flipping - nailing as Mike said, I would nail through two gusset plates and the enclosed 2X with nails long enough to be clenched. All you need is a bit of styrofoam under each gusset palte to accept the nail points.
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Mike and Matt -
Back the horse up here a minute. I've said in the past that Iwas a P.E. - But I always followed that up with the statement that those letters stood for "Pretend Engineer".
I have recieved a great deal of
i training
from engineers, but don't have that little slip of paper that makes me an engineer. I just like to use the "PE" thing as a joke.
One note I would add to William. If you've seen engineered trusses sag, something is wrong. They were installed wrong, overloaded, or designed and/or built wrong. Trusses have a tremendous amount of testing and research that goes into the design. There's no reason that they should sag.
*Ron:OK - I wasn't sure, that's why I added the "(I think)", anyway, like it or not, you are the sites premiere resource for truss information!Regards,Matt
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If you build your own trusses and you are not an engineer, then they AIN"T engineered trusses. I don't buy into the idea that you should grade your own lumber also. There are a lot of things I am not an expert at and I am NOT going to do.
Tim H
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you definately need an engineer if your going to follow our current minimalist approach to building. If you want to use time tested designs, make it alittle beefier than needed, you'll probably be fine.
I've gotten lots of lumber that shows me you don't have to be very good at grading to be a grader. Apparently any moron can do it.
If you don't know enough to know if your buiding alittle beefier than needed, than it is time to stay away from this project.
*let see TIM... if you build your own trusses from a time tested design then they're not an engineered truss.... where do you think the calculations come from? u think they sit down and reinvent the wheel everytime someone wants a truss?you're not thinking like a builder.. and you're not thinking like an engineerif i want to know what the safe load for a beam is ...do i have to hire an engineer?if i want to know what size and spacing of joist to use for the second floor , do i have to consult an engineeer?if i want to know the load bearing capacity of the soils so i can size a footing, do i have to hire an engineer? what do you think builders and designers do when they have these problems....don't be silly...if we're working with spans less than 40', there is no reason a good builder can't look up a stock plan and have complete faith that what they build for a truss will be completely safe.....the problem is when people who don't know how to read plans or execute designs start doing it then buildings start failing.. so they write codes and pass legislation requiring each truss plan to be stamped by a Profesional Engineer....well they didn't pass those laws because of me building something from a tried and tested truss handbook..gimme a break...
*
OK, I'll settle this - and I AM a PE.
Build the trusses with plywood gussets and lots of glue. You could almost not design them poor enough to not handle the loads they will see at 16" OC with only a 28 foot span. Unless you expect to carry a snow load that is 18 feet deep on the roof, I wouldn't worry too much about it.
Having said that, I would just go buy the trusses anyway. You will be making about $.06 per hour with all the time you will have spent milling/stickering/cutting/glueing/nailing these babies.
By the way - if you have seen properly installed commercial trusses sag, then please tell me the name of the company that makes them - they are in dire need of a new engineer.
Adam, P.E.
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Adam -
I'm surprised to hear that, coming from a P.E.
You're right in saying that they would probably overkill most of the things on the trusses if they built their own. But what about the one thing they do wrong ? A truss is like a chain in that it's only as strong as it's weakest link.
Screw up one thing, and all your other efforts are wasted.
*I've never hear a PE talk like that. If you really are a PE, where's your condescending, "all truths are a mystery to all but me" attitude?If you really are a PE, I hope you'll stick around.If you're just some wierd guy with decaying bodies of women in your basement who likes to pretend he's an engineer on the internet, stick around anyway.b I'm not an engineer but I play one on the internet.
*
Nope, I'm the real thing. State of Michigan Professional Engineer license number 46250.
As far as the decaying bodies in the basement, that's a negative. I hate the smell, so I keep them under the chicken coop.
If I remember correctly, a simple king post truss with top and bottom chords that are only 2x4's can span about 27 feet (don't quote me on that - I'm going from memory). If it is rated to span 27 feet, it is probably really good for 35 feet (companies are touchy about lawsuits for some reason). If he uses 2x6s with plywood gussets and construction adhesive, he could park his truck on the roof without worries.
*
Adam -
You're a bit off - a kingpost truss is only good to about 16' in this area. I doubt it would even go that far in michigan, with heavier snow loads.
I've attached a picture of a kingpost truss, just in case that's not what you mean.
Sure, there are safety factors in trusses, just like everything else. But the way we build trusses is also based a great deal on experience, not just span charts.
For instance - We can design trusses with 2X4 chords with 12' panel lengths on the bottom chords, and they work fine. (On paper) But in reality, the chords would be so crooked the drywall ceilings would look like heck. So we don't do it.
Better stick to giving advice on things you know more about.
*well, here's two fer ya.. i think the first is called aand the second i don't know what the name is but i'd guess ...any other common names?...i can find examples of , , ,but the one in the second picture is so common they didn't bother naming it..another question... they refer to 4 panel trusses... and 6 panel trusses, but looking at the diagrams, i can't tell how they count panels...does a refer to the number of divisions of the bottom chord?b inquiring minds want to know
*Over the years, the USDA, USFS, and State University agricultural extensions have compliled thousands of plans for homes, barns, shops, and other structures. Go to http://www.ag.ndsu.nodak.edu/abeng/plans/7010.pdf for an example. These plans are designed for low cost construction by self reliant people. Many include site built trusses. I suggest you contact your agricultural extension to see what plans are available. You will most likely have to pay for reproduction and shipping but it will not be very much.
*
I stand corrected - guess that's why I added that I was going by memory and to not quote me. I'm guessing I was remembering some of the data from Fink truss tables with 2x4 top and bottom chords. I'm quite sure a Fink truss can handle 28 feet without any trouble with 2x4's as the structure. If not, I guess I better sue the company that built the trusses I used when I built my house.
Tell me, Ron - do you use the Method of Joints, the Method of Sections, or FEA analysis when designing your trusses? How do you find allowable stresses for the wood materials that can vary in quality and moisture content? Exactly what is the factor of safety that you use in your computations? 1.1? 1.5? 2.0?
Just curious - never did much calculating with wooden members before. By the way - thanks for the pic of the king post truss - do you have any pics that can help me figure out the difference between a hammer and a bulldozer?
*
Actually, Adam, we use different methods for different types of trusses. Floor trusses, pole barn trusses, and typical 2' on center trusses all call for different types of analysis.
We don't recommend metal plate connected trusses in high moisture environments, so moisture doesn't come into play.
We don't build safety factors into the design equations- they're built into the lumber and plate design values. Typically they're the average test ultimate divided by 3.
Don't have any pictures of hammers or buldozers. But I like to play with both....................(-:
*Hot topic,An issue being missed here might be the gusset attachment. The roughsawn, undressed lumber will not be conductive to the typical glues. Only construction adhesive would apear to have the gap filling properties required. I don't believe that it is recommended for most structural applications. Big gussets, construction adhesive glued, and clinch nailed with good quality nails would be my solution.Does the foaming urethane glues have the gap-filling qualities required?joe d
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There is a trial version of a structural analysis program on the web called Cadre-kind of fun to play with. I think it is at http://www.cadre.com but I'm not sure.
*
yeh, those foaming ones are great.. the ones that rely on moisture in the wood to kick the reaction...
to the point that if the wood is questionably dry , i'll lick the joist before gluing, or if i was actually an organized person, i might even keep a damp rag around..
the old resourcinal glues wouldn't have a problem either, the first time i saw them in use must be thirty years ago with rough sawn oak ribs in a newfie being bilt in one of the last of the wooden ship building yards around here..remember that stuff...Elmer or Weldwood, in the pop-off can cover... deep purple .. oozing all over the place..
....i think it was colored like that so you could see if you got any in the joint..
but,...... and i cud be wrong.....i think with the right nailing schedule, you cud eliminate the glue on the gussets.... there is no glue on the metal plates, is there?
the plywood gussetts are larger sized than the metal plates.. i'll bet that in most instances , the glue is window dressing or overkill..
*joe d,That N. Dakota site Steve Hansen posted is the cat's meow. I knew there must be USDA plans online somewhere but none of my searches ever turned them up. Too bad they havent got the older big paper plans scanned in. Good news for us as Oregonians is that if you call OSU's ext. office with a plan#, they'll print it and send it to you for free.JonC
*adam.. can't u trade some of your M.E./ P.E. work for some structural or architectural work?
*
Mike - you find me a architect or good framing contractor who needs some machine design work done on the side, and we've got a deal.
Funny thing about the PE license - my stamp looks exactly the same as a PE in chemical engineering, which looks the same as civil engineering, which looks the same as.......
*
funny thing about yur P.E. license is..yu don't keep up on the licensing tendencies...
you are limited in Rhode Island to practising within your field of expertise...if you put your stamp on a structural print in Rhode Island someone would bring you before the licesning board and there would be a hearing and your license would be suspended and the results would be published in the paper....
and Rhode Island is not alone in this trend...
now P.E.'s with long experience have to be recertified in Rhode Island to keep practising in their field of endeavor... do i think this is right?..no, but do i think a guy designing machine parts shud be able to put his stamp on a structural drawing ,, or a soils engineering drawing?...no....
check it out adam,.. its comming to a jurisdiction near you.....
*Adam - You bring up an interesting point. Why don't engineers have different stamps and/or classifications for different areas of expertise ?I'm not criticizing, just curious.
*I've got a bsme and I never even knew there was such a thing as a PE in anything other than civil/structural engineering. And I do think that a PE in one specialty has enough understanding of the properties of nature, the rules of the universe, to keep something working in another specialty.A machine designer won't know the common conventions in residential construction but could sure design one that wouldn't fall down.
*
Agreed - the main logic behind having one stamp for all PEs is that each person is supposed to be intelligent and honest enough to know his or her limitations. My PE is in mechanical engineering, but there are some electrical applications that I would not hesitate to put my seal on. I wouldn't come within 10,000 miles of sealing anything chemically related.
In the mechanical field, unless you deal heavily in government contract work, the PE is mainly a "badge of honor" and resume builder. My seal is on top of my computer as we speak - it's never stamped anything other than for fun.
My understanding is this (and they DON'T spell things out very clearly when issueing the license): I can seal any work that I want, but I am legally liable for any damages that occur if my work is proven to be faulty. This could even include jail time if someone gets hurt. None of the PEs that I know are very anxious to go stamping things they don't completely understand.
I don't know the most efficient way to handle a framing crew, I don't know the correct terms for valley jack vs hip jack vs whatever rafters, but I do know that I could build a house that won't fall down.
*
im just tellin u... its headin yur way...YOUR P.E. license is gonna be limited unless the small independent PE's can lobby effectively..
the big engineering firms benefit by limiting the scope of the license, since they can have as many on staff as the need...
the one man shop is gonna find themselves scrambling to stay in business....
ignore this at your peril....
*Adam - I guess what I was wondering was if having different seals for HVAC, electrical, etc. might help i limityour liability. If engineers are anything like truss companies, they get sued for a lot of stupid stuff. So maybe if an engineer only had a HVAC license he would be less likely to be sued over something he had nothing to do with ?Maybe we ought to start another thread - we could spend a lotta time on this.................(-:~
*
I am purchasing a bandsaw mill which cuts wood a maximum of 16ft. in
length. I want to build a workshop with a 6/12 pitch roof to match my
house. I want the building to be at least 28 ft. wide and about 48 feet
long. I am considering making roof truss in order to save money and I
need information on how to do this (where to buy metal plates, what are
my limits in width, web placements).
*Bill... IMHO...i don't think u can save any money..cause time is money...by the time u do the engineering, buy the plates , figger the cuts ... and then fabricate em.;.. you could have devoted that time to flipping hamburgers at mcDonalds and been ahead of the game....i've bilt trusses that didn't require any enginering... standard designs, relatively short spans, 2x6 top & bottom chords , plywood plates, out in the boonies, a long ways from my normal suppliers, etc..so flip some burgers, or better yet , put your mill to work making money so u can buy yur trusses and get under cover and in production faster..b but hey, whadda i know?but when u price the trusses u r describing , i think u'll find you shud try to save your money some place else...
*William,If you live in a rural area, with lax or nonexistant inspection rqmts. you could build your own, just go to a lumber yard that stocks standard size trusses, measure them off, make a drawing, and go home and duplicate.I wouldn't use the metal plates though. Make plywood gussets, glue and staple the bejesus out of them, and install.I'm not far from a rural area where half the outbuildings were built this way. Haven't seen any failures yet. I know the by the book guys are going to have a field day with this, but it's fairly common out in the sticks.I added on to a horse barn once that had home made, bastard size, trusses(4 3/4 / 12 or something like that). Rather than try to order them from the truss company and hope they matched up, I just duplicated what the Amish crew had done originally. Worked great and it was kind of fun.Just as a cautionary note: I would only do this if your talking less than 30 ft. And don't call me if your roof collapses! : }John
*I can't imagine building trusses for less money than you can buy them. Check out the price of manufactured trusses, it may be alot less then you think. Surely less than your band saw.
*I hear ya about the roof collapsing JRS! Tore down a 50' by 100' riding arena last spring here in Michigan when the snow load caved the roof in. These trusses looked home made and were on 8' centers! Still, it held up for about 25 years (found a date on one of the corner posts)It collapsed in January-had a hell of a time getting everything out and using part of it as a run in shed until a new barn was built.
*William - I agree with all these other guys. By the time you dry your lumber, and figure out the engineering issues, you'll have an incredible amount of time invested. And you won't have any idea how strong they are once they're built. Seems like we've answered this question a lot, guys. Think we could add it in the FAQ, if we get it up and running one of these days ?
*If you feel like this is something you have to do and code is not an issue, check with you extension service. They should have a catalog of USDA farm building plans, including truss designs free. Just be aware that some of these plans are really dated, many from the 1950's. For instance the little 20x30 shed roof pole barn plan I used as the basis for a feed shed I'm putting up had 4x4 posts 12' o.c., 2x8 girders and not a scrap of wind bracing. There's probably some of them still standing but I sure dont have that kind of guts.JonC
*It wasn't only saving money that encouraged me to do this. I've bought so many eng. truss in the past andseen so many sag over time, I thought I could do it better, as well as cheaper. I would start with a std. fink design and use undressed 2x4 or 2x6 Loblolly Pine and space them 16"o.c. We have 132 acres of mixed hardwoods and pine that I need to thin out without destroying theland which my home sits in the middle of. What if I built the foundation and deck and assembled the truss on it? I could Snap a chalk line and nail down 2x4 blocks to keep everything the same.Then I could pre-cut my 2x4's(or 6's) to thecorrect lengths and angles. Also I could cut all of my plywood gussets in advance and have my nail gun at ready. Sounds like Henry Ford might be impressed. Two more questions: 1. would it be OK to air-dry the pine for ~90days getting it to ~16-18%m.c.? 2.What kind of glue should I use on the gussets?
*Bill , have at it...build a little camber in .. say one inch.. and set up the jig you described.....i wouldn't bother with the 16 inches OC.. maybe change the chords to 2x6... set up a nice nail pattern for your gussets, and i like a resourcinol glue.... but some of these gorilla.. and pl 's look pretty promising....rack and sticker your stock and measure it with a moisture meter... if you're really into it you can set up a solar kiln and hustle the process.. one of my friends had a solar kiln .. worked great.. don't know where he got the plans.. but one of the alternative energy sites will have one .. or maybe even fine woodworking...nail it off, flip it out of your jig, flip it over , nail the other side, and stack em....if there is no jurisdiction.. just go to one of the pre-engineered designs and have at it... 28 ft. is no big deal......i still think you'd be better off trading lumber for money and buying your trusses... but if you want to do it have fun....we did...here's some pics of pics we took in 1975...hasn't deflected an inch in 24 ft.ps.. the guy on the step ladder is 90 now, and was still walkin the woods with his coon hounds two years ago.Kermit
*William:Not meaning to pi$$ on your parade, but engineered trusses are built of i graded lumber. You say "would it be OK to air-dry the pine for ~90days getting it to ~16-18%m.c.?" - So, you are telling us that you live in an area of 16 - 18% humidity? I think, really, what you are talking is non-engineered trusses. If you want to save money on glue, why not just use pine sap? Just as an FYI, Ron S., who responded above is not only a PE (I believe) but also a truss engineer. What's the advantage of using trusses? - why not just stick frame it? - unless you are looking for no interior supports (posts)? Idon'tknow - maybe FH BT just isn't the best place to learn about barn building???Just to show you I'm not a bad sport, I'll send you the engineering sheets from some 30' trusses that we just installed - if you want. On the other hand, your 16' material would not quite make it for the top cord??... maybe some 26 footers?? - no, wait a minute - those were 5:12.
*Matt...just for the sake of arguing...(it's so much fun).. if he's cutting his own stock , he can certainly GRADE his own stock.. and keep the best for his trusses...he can use the same grading rules the inspectors use..since he's going into the lumber business, its time he learned about grading anyways...and species...is .. species..the top chord doesn't have to be continuous, but can be spliced.. and so can the bottom chord..my suggestion was to increase the stock from 2x4 to 2x6 to build in a little more safety in his design.. and the camber to make up for the lack of presses that the truss mfrs use...long before ther were truss mfrs. there were job site built trusses... as long as no one is stretching the envelope here.. and there is no building inspection jurisdiction to contend with , then practical time tested carpentry should prevail...and i don't suggest that everyone build their own trusses, but William's situation cries out for this...Ron is a P E, and has given a lot of good advice about trusses and truss erection.. but the techniques of truss fabrication are still just an evolution of age old building techniques... simple pitched truss designs with all of their limitations are published in many different sources....if i want a scissors truss, or anything i'm going to submit to a building inspector, then i have to have a stamped drawing, but short of that, all i have to do is follow generally accepted practise...b but hey, whadda i know?
*Mike:Yea - this guy can undoubtedly do this successfully - it just seems that sometimes folks just show up here looking for someone to agree with what they want to do. At least you all got him off the idea of using metal plates. Years ago I worked in a truss plant - the machine we used to smash those plates down was incredible. A huge roller that exerted - probably tons - of force as it rolled over the truss. Personally, I'd rather just order what I need, get the project done in less than 4 years, and, as you said - save my time for something more productive.Which reminds me of something else - William: Consider using AdvanTech (sp?) floor sheathing. It can tolerate being exposed for relatively long period of time.
*Matt.. we finally got the permits for our next house.. what a fiasco..anyhow i'm specing Advantech for floor, walls and roof sheathing....i'm being quoted $22.50 for the 3/4..(T&G)$19.55 for the 5/8 (T&G) and $15.99 for the 1/2" do you have any current quotes there in Raleighthese prices are higher than CDX fir... what's up with that? Mike
*Not wanting to step on anyones toes, but if I didn'tthink I could do this successfully, I wouldn't havebrought it up. I'm trying to keep an open mind andtie up loose ends at the same time. I hadn't thoughtof sap until I read Matt's response.I wish we had 16-18% hudmidity in N.C. Maybe I couldstop sweating so much. The sawmills I spoke with tell me 2x4's stickered and covered in the good old summer time will dry to ~16-18% M.C. They tell me I should then either kiln dry it or use it.I realize that I will have to splice both upper chords (& 1 lower). If I could cut 32 ft. 2x4's, I would not have needed any help. I've noticed store bought truss use shorter 2x4's and stamp them together.I thought I would half-lap ~4" end to end and put a web directly under it and, of course, a ply gusset on each side.Matt, I was getting ready to post this and saw another message from you. Last week I checked on using Advantech flooring when I began dreaming this up. I decided to use it and probably a roll of plastic. Good idea.
*I haven't seen the Advantec here but I just bought 60 sheets of 5/8 CDX for $19.95. almost a wash.
*William.. i wudn't lap splice any members in a truss..i'd butt splice and gussett them ...and they don't have to fall on a connection point either...email me and i'll FAX you a copy of the AGS plan i used 25 years ago....
*Mike:The last time I priced Advantech 3/4" T&G (about 3 months ago) it was $20.95 a sheet - but a lot could have changed since then. At that time it was ~$2 more than OSB and ~$2 less than plywood. William:The thing about pine sap was a joke... Use construction adhesive or whatever Mike suggests. BTW - I did the plywood gusset truss thing with a small (~ 16 x 18 I think) barn with a gambrel roof once quite a while back.