Can anyone tell me what the joist span limit is for 4 x 10’s spaced 14″? I’m considering sistering my existing 2 x 10’s to enable the removing of a bearing wall and opening up my living room to 17″. If I do this, should I bolt or nail the joists together? How far apart should the fasteners be spaced?
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Replies
Why are you bringing this up again? Lose the old thread you started ??
http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=20397.1
x
This is a slightly different question so I figured a fresh thread was appropriate. I have been unable to locate a span table that lists 4 x 10's. Can you help with this?
Wealth is
not created, it's
consolidated.
This is when a structural engineer is required. If you cannot even find load tables, you should not be using them. Also, and engineer will keep you from posting about 2x16's next week....that's not a mistake, it's rustic
You can find SYP span tables at:
http://www.southernpine.com/tables/
But you don't have 4X10s - Your lumber is still 2X10s. If you add extra joists, you're just reducing the effective spacing.
But - as I said in the other thread - 2X10s shouldn't span 17'. I don't care what the span charts say. And you still need to make sure there aren't any loads applied from above. And check local codes.
Sometimes I wish life had subtitles.
Thank you all for your answers, even the snappy ones.
Boss, what is effective spacing?
Please excuse me if I'm wrong, but I'm not sure that you understand what I'm considering. If I sister new 2X10's to the existing ones then I have effectively made 4X10's right?
Also what is the right way to sister joists? How far apart should the fasteners be? Should the fasteners be bolts or nails?
Wealth is
not created, it's
consolidated.
Sistering 2X10s together doesn't make 4X10s. It just makes double 2X10s.
What I meant by "effective spacing" is this: You're proposing taking 2X10s at 16" O.C. and doubling them up. What you're effectively doing is making the 2x10s 8" O.C.
I don't think it's appropriate to give out fastening advice when I think you're doing something that's inherently wrong........
Never fight ugly people they have nothing to loose.
For the purposes of engineering calculations -- bending moment, deflection, end bearing, horizontal shear -- two pieces of lumber sistered would be exactly the same as a single piece of the same dimensions, provided they're all the same grade. Section modulus and all that stuff is linear with respect to width.
But there are no span tables for that, because that's not what happens in the real world. Sistering two new 2x10's produces a beam 3" wide, while a new 4x10 is actually 3 1/2" wide.
Sistering a new 2x10 to an old one (full 2"), which is what I'm doing in my bathroom, does produce a beam 3 1/2" wide, identical to a modern 4x10. But that's just identical for size. In my case, the sisters are select structural, and the original joists are from before there was such a thing as grade stamps on lumber. So how do you do a span table for that? That's why these cases have to be individually engineered. Span tables are only for the everyday stuff.
As for nailing schedules, check with your local building department. Many of them have a xeroxed handout of code basics that include all that and more. Or you may find that your engineer will go to the city and pull the permit for you. Ask him to pick up their handout, too.
-- J.S.
two pieces of lumber sistered would be exactly the same as a single piece of the same dimensions, provided they're all the same grade.
Not necessarilly - After NDS-91, lumber grades had different values for different sizes.
There is a booklet from NHAB that lists allowable live loads for built up wood beams by the the species and grade. Also the bearing requirements are listed.
Double SYP #2 2x10's on a 17ft span are listed at 74 lb/ft.
A single SYP #2 4x10 @ 17ft is listed at 87 lb/ft.
These charts list values to 20 ft spans, but as BossHog said, the span and loading needs an engineer to detail and calculate.
How about a fletch beam?..........................................Iron Helix
Wow, thanks for all the detailed responses.
What is this fletch beam?
Wealth is
not created, it's
consolidated.
> What is this fletch beam?
It's a sandwich -- your existing wood joists between steel plates. Might be overkill for this situation, your engineer may well find a less expensive solution.
Where are you located? Perhaps someone here can recommend an engineer.
-- J.S.
I'm in the Hudson Valley, south of Albany, NY.
Wealth is
not created, it's
consolidated.
First let me correct my spelling...it is a flitch plate beam, not fletch!
Don't ask what a "fletch" is......my son informed me of its slang meaning.....nasty!
More Info.......................From NAHB booklet #5 ...Table #27.................
2 wood members 2x10 SYP #2 with a 9"x 1/8' thick steel plate @ 17 ft span has an allowable uniform load of 120 lb/ft.
2 wood menbers as above with a 9"x 1/4" plate @17 ft = 173lb/ft.
Can you determine the total loading, including point loads?
If yes, your conclusions are your own liabilities.
If no, then the engineer you hire has his own liability insurance if he is incorrect!
Your choice................................................good luck.....................Iron Helix
>> ... my son informed me of its slang meaning.....nasty!
That word is felch, and yes, it is extremely nasty.
I couldn't find a definition under either spelling. Tried dictionary.com and google. I don't have a son. Any suggestions?
Fletch has to do with attaching feathers to arrows. Fletcher, for instance, is an ancient and honorable occupational surname.
As for felch, don't look it up. You don't want to know. It's really, really nasty. But if, like the Elephant Child, you are 'satiably curious, try http://mindprod.com/ggloss.html#FELCH
Somewhere along the great, grey-green, greasy Limpopo River.
Edited 5/31/2002 1:11:34 AM ET by Uncle Dunc
Edited 5/31/2002 1:25:35 AM ET by Uncle Dunc
Edited 5/31/2002 1:26:12 AM ET by Uncle Dunc
Jeez, this topic sure took a turn, anyway, thanks for all your help with this one. I'll be calling an engineer to figure this out for me and for liability.
Thanks again,
Cesar
Wealth is
not created, it's
consolidated.
Don't take it personally - Sometimes threads on this board really go off for no apparent reason. Ask the same question a month later, and it'll hardly stir up any dust at all.
Good luck with your project..................
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