not a deck, but about joists

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  #1  
Old 04-01-02, 08:36 PM
1badKX
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not a deck, but about joists

I'm putting an addition on my house this summer and have actually build an entire house before with a couple guys, but i forget about floor joists...can i get by with spanning 2x10 joists 16" on center 23' and not having a support beam in the center? or maybe go to 12" on center? or maybe even 2x12 on 16 or 12" centers?
 
  #2  
Old 04-05-02, 02:17 PM
josh1
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not even close... if you get 18 " I joists you can free span 24' .. not possible with 2x10s...

Hope this helps--Josh
 
  #3  
Old 04-08-02, 04:07 PM
acebren
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joist span

You left to many things out.
your addition is 23X?
you could break span in half and use a LVL with joist hangers on both sides.
You could use LVLs, TJIs, or 2x4 engineered trusses.
many different options but you need to give more info.
 
  #4  
Old 04-08-02, 08:51 PM
josh1
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the 18" wooden engineered I joists are perfectly straight no crown .. a breeze to install ..just like regular floor joists .. this is what i would recommend if you want simplicstic and still able to span 24' without any mid supports.. check your local lumber supplier ..they can tell you alot more about wooden I joists


Hope this helps--Josh
 
  #5  
Old 04-08-02, 10:41 PM
acebren
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joist span

18 " TJI is overkill you can easily span up to 30ft with 11 7/8 TJI 350 series easily but what I was trying to say earlier was that you might not have to go through all of the expense of buying all TJIs or LVLs if you put a double LVL at half way point of your span and go from one side of the addition to the LVLwith 2x10 joist. Hangers on both ends of the 2x10 then go from the other side of the LVL to the other side of the addition with 2x10. Joist hangers on the LVL side and resting the other end of the 2x10 on the top plate of the exterior wall. The only other thing that you will have to do is put 2 or 3 2x4 or 2x6 (depending ot the thickness of the wall it is resting on) directly under each end of the LVL so that the load can be transferred down to the foundation.
 
  #6  
Old 04-09-02, 02:08 AM
josh1
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flooring

The idea is only that the most perfectly *level* floor will be acheived using the I joists... a notable improvement over dimeninsional lumber and also has pre cut wire knock outs to save time wiring. Yes an LVL header could be built.. but i do believe 3 or more LVLs need to be through bolted and all LVLs should be tied with metal straps.. not to mention the weight of some 20+ foot 3 beam header if you are DIY... and the load must be supported continously to the basement or crawlspace.. which can involve cutting small blocks to fit under the first floor depending where your columns end up. For my money at least the I joists are alot simpler.

Hope this helps---Josh
 
  #7  
Old 04-09-02, 08:33 AM
acebren
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joist span

I agree with you josh on straightness nothing better than TJI or LVL or any engineered lumber system. Cost for most DYIs is final determining factor and 3 LVLs are cheaper than a whole flooring system of engineered lumber. Weight isn't really a factor because you can pre drill on the floor and then install LVLs then bolt together after they are in place.
 
 

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