If you had the chance in your own addition would you design your floor framing with I-joists or standard dimensional lumber. Span is 15′ 4″, one of my buddies has a strong dislike of engineered joists, claims he always senses a bit of deflection and is urging me to go with 2×12’s. Yet I know some people use them all the time.
This is for a 2 story addition over a garage we are framing ourselves and only 1 of us has experience with the engineered products. Price difference not a huge concern, production speed important but not primary, much more important to be happy with the end result.
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It's all about the spans baby! Properly sized I-joists will give you a better 'feeling' floor and it will also be flatter and truer than conventional lumber can give you. Both conventional lumber and engineered lumber are capable of giving you a floor free from deflection and vibration... but they've got to be sized appropriately. J-joists will just about always give you a flatter floor.
As far as production time.... it depends completely on the footprint of the frame. In a cut-up situation, I find dimensional lumber to be quicker. On runs where the majority of joists are cut to the same length, I find I-joists to be quicker because we rack 'em up and gang cut in one pass.
You're friend... the deflection sensor..... does he build full time? I'm just wondering what his range of experience is to have formed such a steadfast opinion on I-joists deflecting regularly. My experience is just the opposite.
No my friend "The Deflection Sensor" is not a builder. He may actually be one of your worst enemies, an architect!! But he has designed additions for a long time and done a lot of plans for others in our area. He says that during construction when he has gone over to check things out and he finds a bit of spring. Could just be a preconceived notion on his part. My brother who will be helping me build has used them and was very happy.
It simply sounds like your architect does not know how to design with the right I-joists for the spans he creates. That long is better dealt with by using the properly sized i-joists or open web floor trusses. Part of it depends on the depth you have available. Additions need to line up with the rest of the flooring.
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For the record.... I was trying to be humorous, not cynical about your friend. Use whatever you want.
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Do you gang cut with a chainsaw?
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Was that your picture in FHB about 6 issues ago cutting away at a gang of 'em?
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Floor trusses.
Any kind of floor framing will have good results if you follow the manufacturer's guidelines. Any floor system will have problems if you don't.
Your friend the "deflection sensor" is full of it.
There's a thread on Floor Vibration that has a lot of info in it about floor performance.
I don't know if it will help you make a decision. But if you're concerned about performance it's worth reading.
deflation sensor full of it?
Well, perhaps and perhpas he pushes teh limits of I-Joists. I can believe teh latter, since it happens all the time. I have NEVER been in a house with a springy floor constructed with solid lumber, NEVER! Every time I feel a springy floor and ask what the floor is consturcted of, the answer is I-joists. So someone or someones are constantly pushing the limits of I-joists. If I were building I sure would make sure to not push that limit. That does not mean I would not use I-Joist, but I would be damn careful!
He said his friend could feel deflection in EVERY floor that was done with I-joists. I just don't buy that at all.
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common up here. There are lots of floors with 2x8 spanning 13' at a 20"oc layout.you can overspan any material, solid, trusss, or I-joist
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As the others have said, either way. I do know that most firemen, if they have to go into a burning building, would prefer 2X joists under the floor to TJIs.
That's probably an infinitesimally small concern to you at this point, unless you're a fireman.
When I worked for a framer, we did floors that were t&g 3/4" plywood, glued and nailed with ring shanks over I-joists and to me, those floors were like walking on concrete. I found many other floors had bounce to them, but not those. I'm surprised at rthe poster who said just the opposite. i guess it depends on the delth and spacing of the joists. Ours were spaced at 16" o.c.
Floor trusses. Please no!!! not flat at all form my experenices. When people say that they have never felt a bouncy floor from solid lumber and only from I-joists think about this. Most lumber companys dont stock 2by much longer than 16-18' so your span with solid lumber is likly to be only that long. On the other hand I joist can be found at the lumber yard up to 28-30' regularly. So a larger spans of 17-19' ish are more commonly used kind of streaching the rules. Just my 2cents
"Floor trusses....not flat at all form my experenices."
Floor truss quality can vary a great deal from one company to another.
But they'll NEVER be perfectly flat. They're made of 2X lumber, after all. Truss companies can't get perfectly straight lumber any more than anyone else can.
If you are in a spaceship that is traveling at the speed of light, and you turn on the headlights, what happens?
If you are in a spaceship that is traveling at the speed of light, and you turn on the headlights, what happens?
You enter a chronosynclastic infundibulum? You see better? The light can't get out and overflows all over the hood of your spaceship?
i used 2x12s on my own house with a 15'9" span 16" center,heres why,cheaper than i joist,easier to get,i know how to work with them,disadvantage is they are heavier to lay out,takes time to lay the crown up.i use advantech subfloor,great product. floors don't bounce. larry
hand me the chainsaw, i need to trim the casing just a hair.
Woody78,
I am a contractor sales rep for a lumber company and what I can tell you is this....
If you go to your local dealer they can tell you with a software program what the deflection would be for your project with whatever joists. As short as your span is I shouldn't think deflection would be a big issue as long as the joists are at least 11-7/8".
Let me know how it goes.
Greg