I have a question about whether my engineer’s insistence on 2 x 12 (#2 @ 16″ oc) joists is overkill:
(I’m a professional cabinetmaker turned (for the second time) owner builder. I have designed a house and just gotten the engineer’s markup back.)
My second floor involves nothing unusual, in terms of weight, etc.
It is a 24 x 30 box, ledgers hang inside ICFs. So, there is a center beam, therefore the max span of joist is 10’8″. I asked Eingineer whether 2 x 10s wouldnb’t be sufficient and he said that the reason we needed 2 x 12s was to allow the plumbing to perforate the joists. Situation is, toilet waste pipe can run from fixture to a chase in 16′ (4″ drop, right?) Does that preclude 2 x 10s?
Replies
My own take is that cutting a 3 1/2" hole that will vary in height as it slopes would preclude 2"x12" too. Is there no way to run the waste pipe in a bulkhead?
Why aren't you using TJI's? You will have a flat floor with dry material, which you can appreciate as a cabinetmaker. They are very forgiving as far as cutting large holes for plumbing, etc.
John
Yeah, I guess that's what I'll likely do. The thing is I live in Oregon, literally down the road from the mills where these things are produced, and the cost of solid lumber is so much cheaper than engineered. But maybe for the second floor...
You could also try floor trusses at 9.25 deep and only in the area of the plumbing run.That way you could just run the pipes through the Vee's. Check with your truss supplier.
It definitely is overkill.
I would suggest a conversation with your plumber about drain routing before you decide what depth to use.
The usual notation about cutting holes in joists is to keep the holes close to the bearing ends, not in the center 1/3rd of the span. Also to drill the holes in the vertical center of the joist and not to take more than 1/3rd of the material.
That may be why your engineer believes that joists need to be 2X12s, to leave enough material surrounding the holes to comply with the 1/3 rule.
I'm not paraphrasing code here, just repeating what I remember from prints and what I've have been told by plumbers.
Edited 5/14/2008 3:45 pm by Hudson Valley Carpenter
The opposite is true - It's better to have holes in the center 1/3 of the span - Not near the ends.
If the King's English was good enough for Jesus, it's good enough for me [M. Ferguson - Governor of Texas circa 1920]
I'm not the plumber who cuts the holes and my memory for details isn't reliable but why would that be? Seems logical that the greatest load and most likely failure point is the farthest from a bearing end.
Maybe someone will look up the specs on holes in the Uniform Code book for us.
Edited 5/14/2008 11:12 am by Hudson Valley Carpenter
In the middle of the span, the top edge of a joist is in compression and the bottom is in tension. The middle third or so of the joist doesn't do too much in that area. Towards the end of the joists there's more shear, which limits the amount of material that can be removed without compromising the joist.
I doubt therefore I might be.
Granted that you're an expert truss guy...but all the failed joists I've seen have split in the center of the span.
From the JLC field manual:
No notching in the middle 1/3 of a span.
But you can cut appropriately sized holes on any of the 3rds of the span.'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb
But you can cut appropriately sized holes on any of the 3rds of the span.
What's appropriate? Isn't the code more specific than that about size of holes, particularly in relation to the depth of the joist? And where they're located in the vertical plane?
What I'm saying is that the integrity of the joist requires that no more than a certain percentage, one third as I remember, of it's height/depth be cut out as a round hole. And that the hole be place in the center of the joist's height.
Sorry, "appropriate" was my language, not the book's.Hole/notch size:Has to be 2" from top or bottom2x10 -- max hole size is 3" -- max notch depth is 1 1/2"2x12 -- max hole size is 3 3/4" -- max notch depth is 1 7/8"And for what it's worth, any notch on the bottom should be done with angled sides like /-- and not |--|'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb
Thanks for the data.
Sooooo....to answer the O.P.'s question, if the holes for the drain pipe are larger than 3", it looks like he does need to use 2X12s.
Even so, the amount of pitch in sixteen feet of run is going to be very minimal, given the other criteria you mentioned. But minimum pitch is another code question.
Yes, I'd say he'd need 2x12 if he wants to run the pipe through the joists. Assuming he's using 3" pipe for his toilet run, that's got an OD of 3 1/2", so he's already past what's acceptable for 2x10 holes.4" drop over 16' (1/4" per foot) will fit in there, though. If he starts with the top of the hole on the first joist (the one closest to the toilet) 2 1/4" down from the top, he'll wind up with the bottom of the hole on the last joist 2 1/4" up from the bottom. (I think).'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb
Looks like he'd be wise to cut out the holes with the joists on horses, rather than doing it overhead. Not forgetting to pitch the holes properly.
Could be a real PIA, trying to get the drain pipe in place, unless he puts it in while installing the joists. I believe that's what I'd do, cut it for max length, stick it in before completing the run of joists, then cut it to fit later, in place.
Hey HV: That's where I build my first house (Saugerties) and it took me to cabinetmaking, eventually.THanks to all of you from the O.P. Got a lot of info that will help both in decision making and also in construction. I like the idea of cutting the holes before I put the joists up... I'm a cabinetmaker/installer... hate hacking once things are up!BTW. Pet peeve of mine on this site: quit assuming "he." About me, it's wrong. But it also continues the universe where that is the assumption, therefore it becomes the reality. And don't somebody now chime in that I'll like the I joists betterbecause they are lighter! =;-)
Shoot. I'd like the I-joists because it'd be a lot quicker, putting the holes in them.
If it were me, I'd try to figure out a way to run those joists perpendicular, to avoid the hole cutting and pipe fitting problem.
Saugerties, huh? As I recall there's another person who frequents this board from up that-a-way.
"quit assuming "he." About me, it's wrong."
He, she or it. For many here "it" might be the best descriptive pronoun.
Good point about getting that pipe in early before too much surrounding framing is in the way.
If you look at any I-joist literature, you'll see that you can have bigger holes farther in from the bearings. I attached one from Boise Cascade for ya to look over if ya like.
If builders built buildings the way programmers wrote programs, then the first woodpecker that came along would destroy civilization.
My puter doesn't want to open that file Ron, but thanks for loading it up anyway.
I'd only add that engineered I-joists are a different animal from dimensional lumber, with many advantages.
"...engineered I-joists are a different animal from dimensional lumber..."
They're different in many respects. But the thing about the hole sizes and locations is basically the same.
I'm a paranoid exhibitionist. I always feel like I'm being watched, but I don't particularly care.
"...engineered I-joists are a different animal from dimensional lumber..."
They're different in many respects. But the thing about the hole sizes and locations is basically the same.
Actually, they're exactly opposite Boss. I-joists are more forgiving of holes in the center of the span while dimensional lumber has greater allowances at the ends.View Image