finger jointed lumber is typically used for studs
I recently saw finger jointed 2×6 being used as roof rafters
Does that meet code?
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Replies
>>finger jointed lumber is typically used for studs
I recently saw finger jointed 2x6 being used as roof rafters<<
I don't think that would fly with the BI here.
Of course I have never seen a finger jointed stud either for sale or in use.
DE finger joints = trim only, don't know about TX.
Jim
Never underestimate the value of a sharp pencil or good light.
Properly done they have the same strength as the parent wood. I'd have to be pretty sure of the joint, but in theory it could work well.
I'd rather have good finger jointed lumber, than knotty twisty stuff.
that is because you are an idiot . god put the trees we use the trees as we see them we carve we sculpt we weep over them but all that finger jointing ask a trimmer it's like choped meat something like the real thing barbeque anyone.
There's no reason to be a jerk here. The guy just expressed an opinion.
Coward, n.: One who in a perilous emergency thinks with his legs. [Ambrose Bierce]
Maybe you get along with the trees better than you do with human beings. time to back up and apologize. There is a time for every purpose under heaven and there is no cause in this thread for name calling. Save that for the tavern when it is deserved.your opinion is not entirely well founded either. I would not use FG rafters myself, but there are glues that make it possible.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
He only has 5 posts, has noly been a member a coulpe of months, and he's already called someone a jerk. I figured you had to hang around here longer to get to that point.(-:
Q: Why do brides wear white?
A: Because it's nice if the dishwasher matches the stove and refrigerator.
"Properly done they have the same strength as the parent wood"
what on earth are you talking about?!?
how can finger joint studs be "properly done" in a rafter application? View Image View Image
Properly done, that is well machined, tight fitting, and properly glued, with the correct glue; joints are as strong if not stronger than the surrounding wood, and the surrounding wood will fail first, in any application.
Sorry if that goes against your gut feeling.
Have you read the article on bridle joints in the latest Fine Woodworking? All glues except the polyurethane exhibited more strength than the surrounding wood, which broke first under load. And, the polyurethane would probably have been stronger than the wood, if it had been clamped.
Basically modern glues are stronger than the wood they are connecting when properly applied. Polyurethanes have more than twice the tensile strength of lignin that is the natural "glue that binds the fibres together in wood.
Sure, it is just my "opinion", but a very informed opinion, based on a better than average knowledge of the sciences, and recent research. And, I did add the qualifier that I would have to know more about the particular piece, and how it was manufactured. But to just say, "that's bad" because it is new, is a bad practice to get into. There are some very good new materials out there, when they are applied in the manner they were designed for.
Go look at a long glue-lam beam. Are the ends in there butt joints or finger joints? Think there might be a reason for that?
And, realistically the amount of clear straight sound wood out there is very limited. Like I said, I'd rather have a well done finger joint over knots, and twisty, turney "natural" wood any day.
What is your "opinion" based on?
my opinion is base on the real world and experience.
I appreciate your clarification and the information you provided to further strengthen ( no pun intended) your point. At least now I have an idea where your are coming from.
what you are talking about is a purely theoretical application of a something that does not apply to framing at this point in time. To my knowledge the only existing finger joint lumber that exist are those which are rated for a vertical load path. I use these type of studs all the time, both in the 2x6 and 2x4 variety. I have been using them for 10 years. So it is safe to say that I am familiar with not only their qualities but also what they are rated for. I have not seen or heard of any changes in the code where it says any different.
I am quite familiar with qualities and effects of a high performance wood glue. I too have personally seen where the glue at the joint has remained intact, whereas it has been the surrounding wood fibres that tend to beak instead. BUT you seem to be missing something here.....the wood still breaks near the joint. have you ever broken a glue up to find it break in a completely different spot? I sure never have, the glue may have held up, proving the incredible properties of the glue, but the surrounding area is weakened.
furthermore, woodworking applications and techniques are not the same as Framing techniques. I have years of experience framing as well as relatively small amount of woodworking experience. And although one can always find similarities, I will not use framing theories to say that because it works for framing it must also work for woodworking.
You clearly have not worked with much finger joint lumber, otherwise you would know they are not rated for anything other than vertical use and you would also not trust them. what happens if it is a bad batch? I have seen finger joints where all you had to was lean on them and they busted. but you don't know that until pressure is applied. so how do you know the weak ones from the strong ones. you don't, you have to trust em, and you can't in something they are not meant for.
unless the OP saw some high tech highbred that would be most likely very expensive for common rafter application, he was looking at a common finger joint 2x6. I do agree with you that a knotted twisted rafter is not something to want to have, but it is easy to see a bad board and simply not use it. again you would have to trust a finger joint.
as far as glue lams go. I have done a lot more than look at them I have worked with them extensively. I'm well aware the a finger joint is stronger than a butt joint. but we are not talking about a finger joint rafter vs a but joint rafter, we are discussing finger joint vs solid lumber.
"There are some very good new materials out there, when they are applied in the manner they were designed for."
My final question to you is: do you specifically know of and can provide information regarding "finger joint" lumber that is rated for rafter use? because yes there are many new building products that have many advantages, and often are an improvement upon what it substitutes. but unless you know of a specific product, all the "very informed opinion, based on a better than average knowledge of the sciences, and recent research." doesn't mean very much if the product doesn't exist. And it doesn't stand up to what exists in the real world. View Image View Image
We designed a bowling alley in about 1984 in Ottawa that had left over fsr that the owner used to put up a small retail building. The bowling alley had to be non-combustible, but the retail was only about 5000sf and was wood frame. When I came to do the framing inspection I noticed the floor joists were all finger joint. When I pointed it out to the GC he supplied me with product data, and I in turn sent him a letter telling him all material substitutions not approved by us were his responsibility.
I have never seen them since, but they certainly were available in the mid-eighties. One thing I remember about them was that the joint was around a foot long, so maybe they found that the extra wood required to make them wasn't worth it?
Finger joint studs were consistently 25 to 50 cents more expensive here. But the quality of the wood, the fact that they were kiln dried and straight, meant pretty well everyone used them. I've seen the poor quality ones you have experienced, but the ones we got from the Ainsworth mill were great.
For starters:
http://www.awc.org/pdf/wdfDesigningWithLumber.pdf
http://www.quattrotimber.com/quattrospan_roof_rafters.html
http://www.alsc.org/greenbook%20collection/UntreatedProgram_GluedLbrPolicy.PDF
There are undoubtedly more, but this was a ten minute Google search.
I googled around a little bit also since several posts reference availability in their area.
The closest dealer for FG studs is 105 miles away from me - maybe that explains why I have never seen them!
Info which I found indicates vertical use only except the quattro.... group in BC, Canada which indicates rafter uses with the "cert ext..." stamping - long joints in the face.
All others which I found which have the short joints in the edges are vertical use only - could only find offerings to 12'.
Jim
Never underestimate the value of a sharp pencil or good light.
Thanks for the links Jigs...now you are providing something to go by. I have personally never seen or used Structurally engineered finger joists, and had no idea such a thing even existed. I appreciate you enlighting me.
These are clearly a whole different product then the standard finger joists studs which are common place. It would have been helpfull to provide a little more info in your orginal post as I am sure I'm not the only experinced carpenter that could learn something new. I like to learn new things, and now you've got me curious what my local code has to say about this product...especially since they are made here in BC where I live.
Thanks again View Image View Image
We're all here to share and learn.
Glad to have been able to open your eyes to something new.
Did you read my post above? Google on 'structural finger joint'....this is a proven and accepted technology, even if you haven't seen it or the products aren't commonly available in your area. Fingerjointed lumber with a structural grade is interchangeable with solid lumber in both vertical and horizontal applications.Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
No I missed your post, but read it now.
Do you know how often this stuff gets used. Since they make it here in BC where I live, wonder why I don't see em ever. I guess they must be getting used in Specific designed situations. Since most houses use trusses, no need for em there. I have done a fair bit of hand cut roofs on high end homes. we were always using regular dimensional lumber, and LVL's. View Image View Image
Sorry, I don't know. My guess is a lot of it except the vertical studs are made to order, like you say for specific buildings. I've personally never had an occasion where I needed 30' or 40' 2 x material, but it's good to know it's out there. I've seen some of these 'new' materials being stress tested in a university lab in New Brunswick; there is a lot of brainpower going into making good products.Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
Properly done, that is well machined, tight fitting, and properly glued, with the correct glue; joints are as strong if not stronger than the surrounding wood, and the surrounding wood will fail first, in any application.
While I'll admit that you might be right, I'll also say that there is just as much chance that you are not.
Unless you can show me a house that used finger jointed structural members a century or more ago, in roof framing that is subject to the wildest of temperature extremes, and wide fluctuations in humidity.
When the finger jointed stuff lasts that long under those circumstances, you have my permission to dig me up and re-bury me with the stuff.
Till then, I'll remain unconvinced. Let's not forget that it was only a few years ago that we all knew that the polyurethane glues were wonderful stuff.
Politics is the antithesis of problem solving.
"Unless you can show me a house that used finger jointed structural members a century or more ago...."
Plywood wasn't around a century ago. Do you have a problem using it?
Remember, I'm pulling for ya. We're all in this together [Red Green]
Plywood wasn't around a century ago. Do you have a problem using it?
Not nearly as much as I do with OSB -- at least ply is made from sheets of veneer, and I can convince myself that a properly nailed sheet has some inherent strength even if the glue starts to fail.
And although the glue in ply is probably the same as the glue in OSB, I also know that the firemen that I've talked to have their preference.
Politics is the antithesis of problem solving.
"Plywood wasn't around a century ago."Wanna Bet?http://www.redrampant.com/roma/impshields.html
The Romans had their own circualr shield known to them as the parma. It's small size made it the prefefered shield of the encumbered standard bearers.Elements of Construction
Wooden Shieldboard:
In the Republic and early-mid Empire the main body of the scutum was constructed of plywood. Three layers of wood glued together with the grains at right angles for added strength.SamT
Edited 7/16/2007 10:25 pm by SamT
Actually poly glues work really well if they are in fact properly applied. Problem was that the instructions were a little too vague, and the advertising a little over the top. So there are lots of examples of it failing, but in all I have seen it was misapplied.
I do get where you are coming from though. I have severe hesitancies about pex. I know everybody thinks it is great. But, I came out of the Water Works industry, and they spent close on a billion, if not more removing polyethylene services to replaces them when they split. Everybody is saying the crosslinking in pex makes that impossible, but I still don't trust it.
I might run the new service to my house in 1-1/4 pex. That way if it splits in fifteen years, I can use it as a duct to pull copper through without tearing apart the driveway, which I intend to concrete just as soon as I replace the old water service.
Properly done they have the same strength as the parent wood.
Sorry, but I disagree, and you won't convince me different. Finger jointed wood has glue in the joints. Most glues soften with water, and almost all soften with heat.
And if the local fire company ever has any reason to be on or under my roof, I want to know that it won't fail prematurely.
So, I prefer ply over OSB, built up beams and LVLs over LSLs, and real wood over finger jointed stuff for structure.
Politics is the antithesis of problem solving.
"Most glues soften with water, and almost all soften with heat."Defind most? Define Heat.My neighbor built a small wooden boat. Some fasteners, but they are mostly to hold it together until the glue sets..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
My neighbor built a small wooden boat
Not just "small" boats, one of my rides was double-laminated construction--it was at more risk from 20y/o cox's'ns bashing us against companioways and well deck rub rails than from delamination. That after repeated immersion in seawater and operating a pair of Marine V-6 Detroit Diesels run hard.
Would not be the glue I'd worry about, in a stud-grade FG peice of lumber; it'd be a 2x6 used where a 2x8 was wanted. But, I also saw, over the w/e, a hip rafter about 27' long spliced with a couple (one each side) 24" long 2x4s--but, I'm sure the elevty-dozen nails punched in will hold it until the framing crew is done . . . Occupational hazard of my occupation not being around (sorry Bubba)
"until the framing crew is done . . ."LOLSo softly underspoken for a Texan
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
"until the framing crew is done . . ."
Well, it was on an infill lot, so it was not like over to the golf course/cc's subdiv where they'd have to watch the roofers on the framing jsut 1-2 doors down while they worked on the present pig-in-a-poke . . .
I was supposed to go look at one of these 'wonder' houses over near Conroe, but, given how high the rivers are, I decided to go with discretion rather than valor. It's alleged that the hips on a house down there are being made from TJI rim-joist filler, but, that's probably an engineered lumbre product.Occupational hazard of my occupation not being around (sorry Bubba)
I did see 2x12 finger jointed floor joists about 20 years ago, but not since. The 2x4 and 2x6 commonly sold are rated for vertical applications only.
ask me in 100 years #### begets ####.
i love my job
We make finger jointed 2x4 + 2x6 lumber. We've had it tested in tension, but not in bending. At the moment we only sell it for stud use.
We do use it for webs in some smaller hip jacks that have very low forces in the webs. But definitely NOT in chords.
There are different methods of glueing finger jointed stuff, different glues, etc. Whoever manufacturers the finger jointed stuff would have to back it up if it were used in a rafter application. They likely wouldn't do that unless they had done some testing so make sure it would work O.K. in such situations.
Thanks for the feedback. I suspect that the builder incorrectly used some left over finger-jointed wall studs for some of the shorter rafters. The longer rafters were common lumber.
I wouldn't trust any fingerjointed rafter that was longer than 14 1/2".OK, 2', IF it was under 5/8 ply.SamT
There are structural and non-structural finger joints....obviously the non-structural is what you see for trim (and that is expressly designed for paint grade). The structural joints are very strong....the construction grade material has two grades: 'vertical stud' uses PVA, but the 'structural' uses phenol resorcinol formaldehyde glue, and is rated for both vertical and horizontal......it is considered to be as strong as solid wood and can be used interchangeably with solid wood, and is accepted under most if not all codes according to my info. They often get used in other products like I-joists, glulams etc, but the industry is currently making fingerjointed joists and rafters up to 40 feet long. Think about it: the 'blocks' (that's what they call the individual short pieces of wood that gets joined) have all the defects cut out of them......the result is strong. These products have to get tested in labs to get the ratings.
This technology goes back to the '20's; with modern equipment and glues, makes a lot of sense. Lots of info out there on it also.Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
finger jointed trusses
Thanks for your post, there is a lot of confusion out there. I have some homemade trusses made from wood graded stand #1
certified finger joint... or stand #1 cerfied finest lumber available.. My local building offficial seems to think that fingerjoint means junk,period. Do you know where I can get some info on the structual fitness of this wood? He does not want to let me remove an interior wall even though its a clear span truss design. Thanks
,Marty
Certainly it's POSSIBLE to make FJ wood that's as structurally sound as solid wood. Whether it's often done is a dfferent question. And with FJ, especially in tension (as occurs with trusses), you don't tend to see partial failures like you do with solid wood -- it's either together or it isn't.
Homemade trusses are suspect to begin with, and with no engineer to certify that FJ is adequate (eg, there's no engineering calculation of the stress in the tension members), your AHJ had good reason to be concerned. If the tension members were laminated instead of FJ there would be far less concern.
I've been using FJ studs in Austin,TX since about 1995, and in the last couple of years have seen a lot of structural FJ 2x6, rated for ceiling joists and rafters.
I have to admit being more than a little scared the first time I walked out on a 12' 2x6 FJ ceiling joist 10' above a concrete slab, but I haven't heard of or experienced a single failure.
It's nice to be able to cut a 32' rafter without a PITA scarf joint or overlap that throws your plywood layout off.
Presumably, someone has tested and certified them for these applications, and my BI passes them.
If an architect is willing to spec them for a million dollar house, I'm willing to give them a chance.
We have been using finger jointed rafters for about 10 years here in Alabama. The 2x8 and the 2x10 come in longer lengths than solid lumber and it is straighter. There has not been any problem with the joints coming apart.
It does meet code. We brace them up like a regular roof.
James
Nextlevel and Mctex,
Thanks for some "Southern" feedback. It looks like I was not the only one who had/has doubts about finger-joint rafters.
I can see the advantage of the longer length (as long as it is rated). Since the ones I saw were only short I still suspect misuse. I will look for a grade stamp next time.
For something that gives even me hesitation:
http://www.ufpi.com/product/oj/prod/faq.htm
Joists with finger joints and no metal.