If you had your choice which would you choose for floor framing? Wood I-Joist or Floor Trusses?
Seems like trusses require a little design & fab lead time. I like the idea of the open chords of trusses but maybe I’m missing something.
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From my perspective -
Advantages of I-joists -
1. Readily available and relatively cheap
2. Long spans are readily available - We sell up to 48'
3. Cut to fit in the field
.
Disadvantages of I-joists -
1. fire performance
-------------------------------
Advantages of floor trusses -
1. Lots of room for mechanicals (Particularly in deeper depths)
2. Least labor to install
.
Disadvantages of floor trusses -
1. Lead time can be a problem
2. Not easily modified in the field
.
.
There are probably others, but that's all I can think of at the moment.
Yeah but, Boss, I'm sure your point of view is skewed, being a truss designer and such. <G>
I see ads for the i-josits but they never show all the extra labor required for blocking & such... you don't have to have a better product, just better marketing.
The amount of blocking depends on the job. Most jobs that I deal with have no blocking at all. But we also mostly deal with one story houses.
What I say goes.
(Unless DW says it doesn't)
This'll be 2 stories above a basement. I suppose if the truss designer were given an idea of preferred loc for HVAC ducting they could try to accomodate?
Rectangular HVAC ducts in floor trusses have to be roughly halfway between the bearings. Generally I tell people that the rule of thumb is that if you want all your HVAC stuff in the truss space, the trusses need to be at least 18" deep. Otherwise you're gonna have problems.Plumbing lines can be a problem even with 18" deep trusses, depending on where they run in relation to the suply and return air ducts.If you REALLY want the HVAC in the floor system, I'd strongly suggest having your HVAC guy meet with the truss guy BEFORE anything is built. I've done it many times - It avoids most problems.Regarding what you asked about 28' spans - The "Spec House From Hell" has 28' clear span floor trusses. They're 24" deep and 2' O.C. The floor is as solid as any house I've been in that wasn't on a concrete slab.The basement is great. I really like not having a lot of posts & beams to contend with. The depth can sometimes be a problem when you're designing a house. But - Everything's a tradeoff.While you're thinking about floors - Have you thread the thread on floor vibration?http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=21010.1
Nobody Knows The Trouble I've Been
I was already kind of considering the HVAC guy being the first one to to talk to on this project, but maybe I'll just send him to the truss folks and we'll work from there. I've been figuring on an 18" truss. The floor plan was based on 2x12s for floors but the need to put everything in the floor lead me to the trusses but 24" was going require too much of an increase in the direction of the stair runs (already added 2ft) so I'm hoping it can be done with 18s with spans less than 22' ...but now after reading the link to your prior thread I'll have to see if I can make the stairs work with 24s.
back to ciphering and thanks to everyone.
Why don't you give Openjoist 2000 a look. http://www.openjoist2000.com/ I am just getting ready to start construction of a 3000 sf home for my family outside of Philadelphia. Basement will be 10' Superior Wall xi system and prefab Nascor walls from Canada. The Openjoist my choice because it gives you the benefits of open web and I joist since it has 1' trimable ends.John
Very nice but the shipping on those would probably eat my lunch since the closest distributor is MI and I'm in GA. Do they have provisions for HVAV ducting other than the trainlge creted by the web bracing?
John, you know, if you only need 12" of framing there is another option. You can install all the mechanicals below the joists and soffit around them. If layed out properly it can be a design element. Huge expanses of flat ceiling are pretty boring anyway.
"This is a process, not an event."--Sphere
And I'm a legitimate certifiable Tool Whore.--Dieselpig
No argument there Woodguy, but I'd like to have the soffits as an architectural option as opposed to being forced into the issue. I also think the HVAC might be more efficiently located in the floor (ie distribution possibilities).
On a 22' span, I'd personally be happy with anything 16" deep or deeper. And I'm pretty conservative on floor design.
Never turn your back on a threatened danger and try to run away from it. If you do that, you will double the danger. But if you meet it promptly and without flinching, you will reduce the danger by half. Never run away from anything. Never!" [Winston Churchill]
"Yeah but, Boss, I'm sure your point of view is skewed, being a truss designer and such. "
I'm not in the business (mine is telecommunications), but I'd reach the same conclusions as Boss did. I'd love to have atruss-joist based home.
well.. quote it correctly"Yeah but, Boss, I'm sure your point of view is skewed, being a truss designer and such. <G>"
<G> = a little sarcasm/humor in this case.
Thank you for the comparison. I would be interested to know why I-joists have more of a fire problem - is it due to their thinner cross section?
Some of it is just my opinion. Some of it is experience. I don't consider myself an expert on it. I did a thread once where I threw a piece of an I-joist on a brush fire:http://forums.taunton.com/tp-breaktime/messages?msg=37987.1I was really surprised at how fast it burned.One time I met with an I-joist rep who worked for the dealer who sold I-joists to our truss plant. I was curious about the subject, so I asked him about fire performance of I-joists. He said he didn't like to takl about it. If any of our customers brought it up, he suggested trying to change the subject..So how important are the fire concerns? That's up to the individual. I don't think it's an important enough issue that I'd refuse to sell 'em. But I don't really like it, either.
He makes no friend who never made a foe. [Tennyson]
Boss,
I think there have been postings here re: fire vis-a-vis I joist. Some one said that Fire dept. personnel were instructed to evacuate the structure and fight it from outside if exposed I-joist were in use. Just hear-say on my part.
"....evacuate the structure and fight it from outside if exposed I-joist were in use."
When I've given presentations to firefighters, that's exactly what I suggest to'em. But I suggest it on EVERY building, regardless of the construction.
I don't see any point in risking the lives of firefighters just to sava structures.
I Love The Smell Of Sawdust In The Morning
Hey Boss, I've got 11-7/8" I joists at 16" spanning 17'-3" or 6"...can't recall exactly.Anyway, one area of the house has "some" bounce, or vibration (I'm not sure of the difference).Of course the truss guy (Okaw, out of Arthur, IL)said 19" is no problem for these I-joists.The salesman from the yard was out measuring for doors, and said he would bring the truss guy back around, because he felt it was a little substandard also.What is your casual recommendation?Squash blocks mid span?fill in the webs with ply?Box the whole joist with ply?Something else?A medium to large guy named Alan, not an ambiguous female....NOT that there is anything wrong with that.
Edited 3/30/2007 9:55 pm by bigal4102
I ike to limit 11 7/8" I-joists spans to 18'. You're under that limit, but not a whole lot. But I would typically expect your floor to be fine.What's the situation with the house? Still being framed, partially done, or is someone already living in it? The reason I ask is that the vibration may change once things like flooring and furniture are in the house. A beam can contribute to vibration. Is one end of the area supported on a beam? If it is, what are the details on the beam? (Size, type, post spacing, etc.)I don't go for trying to beef up existing joists with plywood. It might possibly work in some cases. But it's basically guesswork, and I don't recommend something unless I'm sure it will work.Stiffness comes from depth, not strength. Since adding stuff on the sides of the I-joists doesn't add depth, I wouldn't expect it to increase stiffness measureably.
All socialism involves slavery. [Herbert Spencer]
Comparing I-joists to factory floor trusses, my impression is that a stiffer floor can be had via floor trusses vs. I-joists of the same height. Care to comment?
BTW - one disadvantage to floor trusses is that the floor system can't really be insulated effectively - OK - maybe with a spray in product.
Also when talking about lead time - the big deal comes into play when it turns out that a truss (or several) were designed (and delivered) incorrectly, and say for example are 3" too short. The order back can be a killer, although my truss supplier usually has 2 or 3 day turnaround on such a screw up. Makes framers very unhappy and rightfully so. As you know, for joists that are too long, a field fix can often be engineered but even that is usually a minimum of a 4 hr delay.
Also, just for the clarifications for those not real familiar with floor trusses, when you said deep floor trusses can cause design problems, (or whatever it was that you said) one thing it equates to is more step risers. For other than large houses, extra feet of length of steps is a BIG deal.
Another comment for the general population here: Even with, say 18" floor trusses putting plumbing and HVAC in the same floor system can be problematic, since if the plumber needs to put in a long horizontal run of pipe this precludes ducts from being run in that area.
Don't get me wrong - I prefer using custom floor trusses if the situation is right.
"my impression is that a stiffer floor can be had via floor trusses vs. I-joists of the same height. Care to comment?"
Yup. I'd say that's absolutely, positively, not exactly right or wrong.
For instance - What brand I-joist are you talking about? Every manufacturer has 3 or 4 different Series of I-joists in different depths. Each one has different characteristics.
With floor trusses - Are they low grade SPF chords, or high grade SYP? How much loading are they designed for?
Have you read the Floor Vibration thread? Based on what I presented there, I believe stiffness is MUCH more a function of the span/depth ratio than what the floor members are.
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Thanks Boss. Good point about the different series of I-joists. I think here, the ones with the 2x4 sized flanges are special order and I've never seen the ones with the 2x2 sized flanges, so I forgot about that. We use LP and GP I joists around here. BTW - yes I've read the floor vibration thread - maybe about 4 times. The first time being when it was at the top of the current topic list...
I know you don't agree with me on this, but I gotta throw it out anyway.I have had several experiences where adding strapping under the TJIs decreases the defl;ection and the vibrations. And it is an easy solution most of the time.
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I don't necessarilly disagree with you. I just don't recommend that anyone do something that *I* don't have firsthand knowledge or experience with. Strapping falls in that catagory.
Ten percent of men prefer women with large thighs.
Another 10% prefer small thighs.
The other 80% prefer something inbetween.
We are presently finishing the inside, no carpet yet.
My framers are as old school as it gets, they didn't like them new fangled I-joists anyway.
I have been told carpet will help, I have also been told I'm being to anal about it.I'll try to throw in a pic .
View Image
Piffin, do you think simple 2x4 strapping on the flat will help, or are you suggesting something else?
I am not against trying something simple as this "problem" is so negligeble, that several people don't recognize it as a problem at all.
They called me anal about a dry basement to, but it is still dry so far.....:>D
A medium to large guy named Alan, not an ambiguous female....NOT that there is anything wrong with that.
Edited 3/31/2007 10:42 am by bigal4102
2x4s would work. We usually use a milled 1x3 sold here as strapping. You could use 1x4 too.The thickness is not so important. What you are doing is turning the floor system from a platform into a thicker diaphragm. The whole floor benefits from having things in tension both ways when somebody walks orjumps around upstairs.Strapping is the norm here in NE and offers many benefits. Added strength is one, sound isoation is another, better attachemnt points for the sheetrock is yet a third.The straping goes on perpendicular to the joists at 16"OC normally. aids performance in much the same way as blocking, bridging, or strongbacksHey, that brings up an idea - did your old school framers install the strongbacks in these web trusses? That could be a part of your problem. I al;ways notice a difference in strength just in the way an open deck walks when we add the strongbacks.
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We can get 1x3's here, but they are pretty ratty, sold as furring, but not intended for what you easterners use them for, they aren't usually very straight and not close to clear.I have I-joists, and my framers did check into necessary blocking, and we were told none was needed.What are you calling strongbacks? We used strongbacks, or stay lath in the roof trusses, to keep them tied together in the middle, and bottom chords, but I don't understand for I-joist, or deck use.The yard guy, said they sometimes specify squash blocks, but strapping would be alot simpler.To jump in on you and Matt's fuel debate, here in the midwest, propane is king, natural is usually available in town.Just like the strapping for drywall, regional differences are pretty significant.A medium to large guy named Alan, not an ambiguous female....NOT that there is anything wrong with that.
I got confused - thought that you had open web trusses which is where you would use a strongback.Squas blocks wouldn't do a thing for you IMO.
Solid blocking might but would be hard to do.So 2x4 would probably your best bet regionally speaking. Your strapping sounds similar to ours tho.Matt and I were just copmparing notes, not arguing in the least. I know about regional diffeernces too, having lied in FL, TX, CO, NY, and more briefly at stops in between.
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Screw the subfloor down with 2-1/2" screws.
I-joists for some reason seem to be stiffer if the subfloor is screwed down.
I will remember before I forget.
That 33' long area - Is that ALL a bearing wall? Or is part of it a beam?
Vision. Tell people you have it - Employers love that crap.
My thoughts exactly. It's only a sketch, but it *looks* like a beam to me, too.Bill
There is a bearing wall the whole length of the basement, but as you can see it is about 3' foot off center. (house is 30'x48').
There is a 10' header (double 2x12 #1 yp on three king studs each end) in the bearing wall roughly 12' from the left end.
At the right end of the bounce area, there is a 5' square hole for a stair opening, with double lvls spanning the 17'4", and two singles heading off the 4 cut I-joists.
View Image
A medium to large guy named Alan, not an ambiguous female....NOT that there is anything wrong with that.
Edited 3/31/2007 8:55 pm by bigal4102
Edited 3/31/2007 9:01 pm by bigal4102
I don't see any "smoking gun" that looks like it's obviously causing problems. I did notice that the "bounce area" is over an area where nothing is below it. To the left you have a non bearing partition that may be dampening vibration. To the right, the mass of the LVLs around the stair opening may also be dampening vibration.It's POSSIBLE that the 2X12 header is contributing very slightly to the bounce of the floor. But I don't think it would make much difference at all. Sorry I can't offer any more helpful suggestions at this point. I still think the floor will likely be O.K. once the house is finished.
If a motorist cuts you off, just turn the other cheek. Nothing gets the message across like a good mooning.
Thanks Boss, I suppose I am being a little overly anal about it, but at least I know if carpet and furnishings don't quiet it down that I can always try strapping or blocking.A medium to large guy named Alan, not an ambiguous female....NOT that there is anything wrong with that.
i can't stand okaw. i have worked with them on 12 projects that i can think of and have problems everytime, good luck getting them to the job site.
now, bosshog's company, worked with them quite a bit, getting ready to work with them again. the one time i had a problem, they came out to the job, talked me through their thinking, gave me hats, shirts, and baseball tickets. they know how to take care of customers. can't speak for boss though, never worked with him yet :)
jeremy
(keyboard is screwy, i tried to capitalize but couldn't)The bad news is you've done exactly the right things to be exactly where you are today.
"IdahoDon 1/31/07"
What's happening with the bounce in your floor is common and is a result of being within code but with long enough spans that the deflection is significant. This is a basic design trade off with any long-span material and is the main reason steel beams and extra long I-joists aren't sized so much for the load, but for the deflection desired. L/360 deflection on 17' is over a half inch.
Even though you may not be using iLevel I-joists, look at the white paper on floor performance for more details, design ideas that could have been used or suggest by those carps who don't know much about new-fangled topics, and a handful of suggested field fixes covering both strapping and the correct way to attach an I-joist block.
http://www.ilevel.com/literature/Floor%20Performance.pdf
Beer was created so carpenters wouldn't rule the world.
Hey thanks a bunch Don, I have been all over that website, thinking we had forgotten blocking or something, but that's the first I've seen that paper.A medium to large guy named Alan, not an ambiguous female....NOT that there is anything wrong with that.
Glue burns hot and thin section fails fast. Firemen hate them
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That pretty well covers it from my POV, with one exception. My lumberyard keeps in stock a couple common sizes of web trusses in a type that have full block trimmable ends, so for instance a 20' long can be trimmed down to something like 17'But lead time is negligable here too, unless there is a unique situation. Most of the time, I can have a floor truss package within eight days from ordering it.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I don't think lead times on floor trusses is generally TOO bad. But - Once in a while when we get really swamped I've seen it drag out a long time. Often when push comes to shove the owner has "pet" customers that get taken care of first. Doesn't happen too often. But when it does it's infuriating.
Every citizen should be a soldier. This was the case with the Greeks and Romans, and must be that of every free state. [Thomas Jefferson]
I recently read a report, can't remember where, that compared the two. The report mentioned problems relating to the strength of the truss member joints (don't know what the plates are called). Rcommended beafing them up with plywood gussets. I really liked the "Trusses" over the I-Joists (due to the open spaces for mechanical, plumbing & electrical) until I read this article.
"The report mentioned problems relating to the strength of the truss member joints (don't know what the plates are called). Rcommended beafing them up with plywood gussets."
I'd be interested in reading that report - Something isn't right. Do you still have it, or know where you read it?
There's no way in hell that correctly designed wood webbed floor trusses need "beefed up".
Strip mining prevents forest fires.
It was some report by "A Learned Expert" that I found on Google under"Residential Trusses". It was referring to the attachment plates.
Another Question: Typically are the brace members also glued?
"Another Question: Typically are the brace members also glued?"
What braces exactly?
Do you mean the web members? Or strongback bracing?
T-shirt: This Isn't Part Of My Rock And Roll Fantasy
Boss,How do the truss plates do in a fire? My guess is that they would fail first (before the wooden members) due to the steel either softening or just conducting the heat into the prongs and charring the wood in contact with the prongs, allowing the loaded plate to pop out. But that is only a guess. Enlighten us, please.Bill
"How do the truss plates do in a fire?"
Complicated subject.
Some people believe they protect the wood by reflecting heat. Others believe they conduct heat into the wood. Some say the fire makes the metal curl. (That last one isn't true)
Based on what I can recall about the subject, I believe the wood fails first inbetween joints most often. I think it's because there's more mass at the web joints.
If you're really interested in the subject, the WTCA started the Carbeck Structural Components Institute to study fire and truss related issues.
http://www.carbeck.org/
I believe they have some online study materials you can check out.
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Thanks for the link. They aren't telling anything without being paid. The relevant CD is $50 plus shipping. I'm not that curious right now.Bill
Dang - I didn't know the CD was $50.I got the 2002 edition at a trade show. If you're interested, drop me a line and I'll make you a copy for nothing.Of course - Shipping and handling will be $49.95.(-:
T-shirt: Please Don't Stare - Jealousy Is So Unattractive
The web members glued to the flange members.
O.K. - You're asking if the wood webbed floor truss webs are glued to the top and bottom chords?They aren't - There's no reason to. The plates are sized to handle the forces in the web and chord members, with a safety factor of three.There's no reason for glue, or the plywood gussets that your "learned expert" recommended.
Caution: Mouth sometimes operates faster than brain
>> I recently read a report, can't remember where, that compared the two. The report mentioned problems relating to the strength of the truss member joints (don't know what the plates are called). Rcommended beafing them up with plywood gussets. I really liked the "Trusses" over the I-Joists (due to the open spaces for mechanical, plumbing & electrical) until I read this article. <<
Probably in an advertisement for I-joists :-) Or maybe on the back of a cereal box... :-) Or maybe in some kind of firefighting journel.
Edited 4/2/2007 7:37 pm ET by Matt
Advantages of floor trusses -
1. Lots of room for mechanicals (Particularly in deeper depths)
2. Least labor to install
It's more than ironic that I view floor trusses as having the highest labor to install. That's been my experience in 95% of the systems I've worked with. The only exception might have been some small 24" modular units with no headers for stairwells.
blue"...
keep looking for customers who want to hire YOU.. all the rest are looking for commodities.. are you a commodity ?... if you get sucked into "free estimates" and "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead high...."
From the best of TauntonU.
What took you so long? I figured you would have been in this thread a long time ago. You seem determined to jump into every truss thread there is and trash the industry and bitch at me.Since you're the only one I've run into in the past 20+ years that dislikes floor trusses so intensely, I pretty much ignore what you say about them.
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87871.68 in reply to 87871.66
What took you so long? I figured you would have been in this thread a long time ago. You seem determined to jump into every truss thread there is and trash the industry and bitch at me.
Since you're the only one I've run into in the past 20+ years that dislikes floor trusses so intensely, I pretty much ignore what you say about them.
I really love trusses. Roof trusses.
I'd also be happier with floor trusses if the sellers of them were a bit more honest about them. I get real tired of having homeowners and builders ask for framing discounts because they spent more for their floor systems based on the industry telling them that they'd save money because labor is less.
That is a bit dishonest and of course you don't seem to mind that carpenters will have to sacrifice their hotdogs and only get to eat buns....
A little more honesty would go a long way to earn the respect for your product that you crave.
If you don't believe the numbers, perhaps you might stand outside and watch a framing crew put together a deck with dimensional lumber, then watch them put one together with floor trusses. To make sure we are talking about apples to apples, let's make sure that the houses being framed have a cantilevered fireplace (normal in our neck of the woods) a cantilevered bay or two or three and at least one stairwell hole. For a bonus, lets put in a stairway hole with a forty five degree angle.
The difference between our opinions about labor is this: truss salepeople talk about theory and I'm talking about actual installation times. Do you really think I'd be praising dimensional lumber systems, with regard to installation time, if I had better sucess with trusses? What is my payoff for lying about my times? Do you think I really care which one is fastest? If concrete pan systems were faster, I'd say so.
And please, go to the girls room with that "bitch at me" statement. My posts are to this forum based on my real life experiences...not to you directly. A poster solicits opinions and as long as my experiences are exactly as yours, I'm okay? Is that what you really want this forum to be?
blue
"...
keep looking for customers who want to hire YOU.. all the rest are looking for commodities.. are you a commodity ?... if you get sucked into "free estimates" and "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead high...."
From the best of TauntonU.
This forum is for EVERYONE'S opinions and experiences - Not just yours. Since I talk to all sorts of contractors about floor trusses and I haven't found one yet who thinks like you do, I'm inclined to ignore your whining and bitching. I'm just tired of it.Feel free to ignore my posts if you want, or to post your opinions to others. If you can't take the heat, get out of the kitchen.
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You are awful hormonal today Boss. Perhaps you might up that dose of estrogen.
I think it might be helpful for you to understand that when I talk about floor truss systems, I'm talking about floor truss systems....not you. You don't have to take anything personal. I think you are a swell guy and add a lot of good information...information that doesn't seem to be coming from any other source....so carry on.
Now, back to our little experiment. Here in MI, we use brick on 95% of the lower levels and project the second story over for brick. So....when you design our test houses, figure in the 4" projection lookout blocks at each end, and add the cantilever in the rear on the second story.
Using the scenario I've described, I'd be willing to bet a dollar to a goose turd that trusses would be 50% more labor. It's quite possible that the trusses might go up to 100% more labor once you start adding the drafstopping requirements that are routinely missed by most contractors.
That said, there's no substitute for the long spans that floor trusses can deliver. Sorry for having different realities....
blue"...
keep looking for customers who want to hire YOU.. all the rest are looking for commodities.. are you a commodity ?... if you get sucked into "free estimates" and "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead high...."
From the best of TauntonU.
just got some advice on my signature line, so this is a little test.A medium to large guy named Alan, not an ambiguous female....NOT that there is anything wrong with that.
againA medium to large guy named Alan, not an ambiguous female.... NOT that there is anything wrong with that.
1 more timeA medium to large guy named Alan, not an ambiguous female......... NOT that there is anything wrong with that.
hey bi gal, this General Discussion folder is a strange place for a tagline post.
be so I thought I'd join in the fun 'fore boss and blue go to fistycuffs.
Parolee # 53804
That post right below yours, almost makes this thread complete eh? ;DA medium to large guy named Alan, not an ambiguous female....
NOT that there is anything wrong with that.
BossHog,
Hopefully this thread has gone on long enough so I can hijack it a little.. (along the same thought)
I used timbers (No sarcasim called for) because they are dramatically cheaper than either I-Joists or Floor Trusses. For example I can buy timbers up to 2"x 12" x20 feet long, for as little as $8.33 each.. (maximum cost if white oak or ash is specified would be $32.00) If I need to combine them together my costs actaully decrease because of less sawing involved.. It's not hard to spec 12"x12" and 18"x18" isn't impossible (22"x22"' is the largest my sawmill can handle but if I needed them I can get up to 34"x34", I'd simply have to haul them further)..
I realize that I can't span the distances discussed here without midspan support, but other than that is there anything that you see wrong with that approach?
Material costs is the highest priority since I haven't figured how to make a profit off the dumb guy that has to do all this work.. (me)
The house I'm working on now has floors full of 14" I-joists with 3 1/2" flanges and triple LVL flush framed beams. It's a three story house. Running mechanicals has been an absolute nightmare. I will go for the floor trusses next time, no question. It would have saved a LOT of aggrevation on this job.
"This is a process, not an event."--Sphere
And I'm a legitimate certifiable Tool Whore.--Dieselpig
The convenience factor for mechanicals has been the primary factor for me on this project I'm contemplating that'll require eveything to be in the floor.
there's trimjoist that has trimmable ends as well as openjoist
that would help with field modification
don't know the price, though
I've built houses using both I-Joists and Floor Trusses. My own home is I-Joists and I really regret using them. I found while nailing the sub-floor down (maybe this could of been avoided using screws) that the top chord of the I-Joist would crack often. And as you may guess, the floor makes some noise in a few spots.
Another nice thing with floor trusses is you can span longer distances with no support. I'm doint a 28' wide ranch house now and the home owner will have a wide open basement with no posts. Definitly nice!!!
upnorthframer
"If you think education is expensive, try ignorance!!!"
re: 28' spans. What kind of deflection is that designed to? What's the spacing?
Never used floor trusses, what are the depths like compared to "i"joists and are the hanger details similar? (HGUSS simpson) LVL's for beams?
I can't specify the deflection off the top of my head, all I know is they are 18" and 16" o.c. and the floor is ROCK SOLID!! I love having 3 1/2" to glue/screw the subfloor to.
upnorthframer
"If you think education is expensive, try ignorance!!!"
I did a 28 with web trusses 18" at 19.2"OC - L360 50# live load, IIRC
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Piffin, You talking about the metal web and wood flanges & ends? If so I forgot about those and need to look in to them as a possibility. I think someone else mentioned them as well. How are they for routing ducting?
The ones I have gotten have something about a 2x3 web that is glued into the top and bottom chords with something that looks like resourcinol and a big mache grover that makes someting like a finger joint on that angle.I have also had many floor joists that have square pockets in them, not just the angular web spaces. can't recall right off if they were the same ones. Not something I paid attention to since we rarely use hot air heat so no ducting
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>>Not something I paid attention to since we rarely use hot air heat so no ducting<<
What kind of heat do you commonly use?
Hydronic from oil-fired boilers. Fed either to radiant in slab via pex or baseboard radiators
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That's what I thought... although the oil part surprises me some. I guess these are existing houses - as opposed to new construction?
BTW - There was a county appraiser out to my building site to look at what I was building a few weeks ago. She asked me if the (new) houses had central heat. I nearly laughed in her face. :-)
Oil is the cheapest BTUs to be had here, except maybe coal which is more inconvenient to use and smelly and takes up space, and.... unless you are cutting and splitting your own hardwood for free.
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We don't see any oil here in new construction. If there is no nat gas available, and someone wanted something better than heat pump/electric strip heat it would be propane. HW radiant floor heat is very rare. Regional differences... Plus, I'm guessing there is no natural gas on an island.
Right assumption on running a nat gas pipeline to an island.Even propane is insanely priced here in part due to shipping. Coast gaurd regs keep tank size down to 100# cylinders. I thinnk one of them is about $79 now. We use them for cooking.Heat pumps are OK in your more temperate climate and the duct sharing when it operates as an AC is fine too, but up here we use AC anywhere from three days to three weeks is all, so I don't even know of any permanent central installations of that.
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For my current project I priced out I-joists, custom built open web metal plate floor trusses, TrimJoist and OpenJoist 2000 for several house designs. The trimjoist and the openJoists were about the same price and more expensive than the I-joists or the custom built floor trusses. I went with the custom build floor trusses. Dimensional lumber wasn't really an option since mechanicals had to be run in the floor systems.
Edited 3/31/2007 9:31 am ET by Matt
One thing to watch out for: With trusses you end up with a larger volume of interconnected space overhead, and fire blocking may be required. Not a big issue, but something to know ahead of time instead of it being an "aw-tihs!" when the insector comes around.
I finally found fire blocking requirement for open trusses in the Fire Protection under Fireblock Draftstop scetion of the code. Thanks for pointing it out. The limit is 1000sqft of space and the solution seems simple enough of 1/2" SR or 3/8" ply (my assumpton follows) & probably fire resistant caulk at the penetrations.
Edited 4/1/2007 10:05 am ET by john7g
I think Boss in the first reply nailed it pretty good.
If you're just taking votes, I'm definately in for trusses. I've honestly just seen too many people not happy with the I joists. And I have no scientific way of finding out if its the joist, the installation, the design, whatever, but bouncy and squeaky lead the gripe list.
I love the ability to put mechanicals in the trusses. No punching holes. Premade routes for HVAC hard runs. Love it, love it.
Of course, you do get into the depth issue. This really can be an important design consideration. A deeper truss, with all its advantages, can make your stair runs consume more floor space. Say you find a house plan you like and switch from a 12" I joist to a 24" truss . . . you added a tread and riser. Just one of those little details. And it does, or can do, the same thing on the exterior. If you're using brick or stone, what's the extra foot going to cost you around the circumference of the house? That can add up.
Nevertheless, I still think its a superior product. Like most, you have to be willing to pay for it, and everything that goes with it.
Real trucks dont have sparkplugs
This was a very interesting read. For someone whose never seen a home built with ijoists - do you run the hvac duct work through the ijoists or below it? I imagine you they'd be the same as dimensional lumber but I hate to assume.
Yes, the same and they have the same HVAC issues that solid wood does.
I appreciate the verification.
Your question is posed within a complete design criteria vacuum. All building materials offer an almost endless advantages and disadvantages that could be, arguably, both relevant and irrelevant depending on how they are used in any particular building structure. That's why the answers to this ridiculous question are futile and all over the place. Sometimes it's better to just call a spade a spade...and move on.
There is a good discussion in this thread.
Based on your longevity posting to this periodical, I decided to give it a read through. My final analysis: If you consider random thoughts and anecdotes---which are full of cognitive dissonance-- a good discussion, then perhaps. Everyone should be entitled to their opinion. My only caveat to that is: Please don't make the mistake of couching opinion as fact.
Any "good" part of the discussion appears based on referenced links that are no longer active. That is one red flag for me. Then, when I read that someone recomends using 2.5" subfloor screws to increase floor stiffness (#48), it really gets to be too much. On the other hand, the white paper reference on floor performance [link provided by IdahoDon (#66)] seems like it would have been informative but, alas, that has apparently been pulled by Weyerhaeuser too. There IS a white paper covering floor performance on Weyerhaeuser website now, but it is dated Dec. 2020 and post dates this thread by a long shot. If that paper makes this thread "good" for anyone that happens to suffer through it at this point, then more power to 'em.
So, where have you been?