Replies

1. 
   JDRHI | May 22, 2002 05:09am | #1

   I`m am not an engineer, but that sounds like a terrible idea to me. A 17' span is going to have much deflection in 2 x 10 joists.

   Is it possible to upset a girder at 8 1/2 ' and post it down to the foundation? Just a suggestion, but I`d call in an engineer or speak to your local inspector.

   J. D. Reynolds

   Home Improvements

   "DO IT RIGHT, DO IT ONCE"

1. 
   CesarNicolau | May 22, 2002 11:17pm | #3

   Thank you for your input, your concern matches mine. I would not want to send any columns to the basement as this would cut right through my tenants' living room on the first floor.

   I did consult a wood joist span table and for 2x10 on 16" centers the table limits the builder a 14'9" span @ 40#psf live load and 13'2" @ 60#psf (as limited by deflection). The floor in question has held for 100 years with a 13'7" span (it is true 2x10 rough cut dimensional). If I add joists in every bay, creating 8" centers will this allow me to stretch the span to the desired 17'3" without bearing wall?

1. 
   BossHog | May 23, 2002 02:36pm | #7

   Jaybird -

   You can probbaly add enough of something to technically achieve the 17' span, whether it's more lumber or I-joists.

   But you still have a poor length/depth ratio of about 22-1. I don't like to see floor systems at about 18-1. For 2X10s, that would be about 14'.

   Also - Since none of us here can see your project, we don't know everything we need to know about it. Is there anything above thr floor that needs to be dealt with if you're removing a bearing wall? What about your local codes?

   If you don't like the news, go out and make some of your own.

1. 
   CesarNicolau | May 23, 2002 04:08pm | #8

   Thank you all for your input.

   There is more house above the aforementioned bearing wall, bedrooms and closets directly above and an attic above that. There are no mechanicals.

   Insofar as local codes? I'll get back to you on that...

   If nothing else, this discussion has sobered me up on my ability to reason out a solution on my own and see the need for some experience and expertise on this one.

2. 
   BossHog | May 22, 2002 02:14pm | #2

   Two things -

   Jaybird is right - No way 2X10 joists should span 17'.

   And we certainly don't have anywhere near enough info to reach any sort of conclusion about this situation. We seem to throw out the phrase "you need an engineer" out quite a bit, but I think it definitely applies in this case.

   One other note - The outside walls being brick doesn't matter - They don't help hold up the structure. In fact, the structure helps hold up the brick.

   I keep telling myself that I am a pathological liar, but I am not sure if I believe it

3. 
   JohnSprung | May 23, 2002 02:05am | #4

   The handy dandy span table from LADBS says that 2x10's of Doug Fir #2 or better are good for 16'-3" if placed on 12" centers, so, close but no cigar.  Going to 8" centers would really be a pain, because you'd have very little room for any work you need to do in there.  It would be tough even to work with a palm nailer in that space.  There's no advantage to 8" centers in terms of span, so you'd do better to sister the existing joists, making them equivalent to 4x10's on 16" centers.  You could also use better material, like Select Structural instead of #2.  Something like that will probably work, but it's out of the standard table realm and into what will need a wet stamp from an engineer before they'll check your plans. 

   -- J.S.

   
   

   ---

   Edited 5/22/2002 7:08:08 PM ET by JOHN_SPRUNG

1. 
   DBuilders | May 23, 2002 02:26am | #5

   Just a thought, TJI 250 joists can span 17'-10" @ 16"OC.  That is at minimum loads (40PSF live load, 10PSF dead load, L/360).  You can go to the 350 and 550 series which can carry more live and dead load or maybe sister them to the existing 2X10's.

   Ken D.

1. 
   BungalowJeff | May 23, 2002 08:09am | #6

   Definitely consider sistering the joists instead of the 8" spacing as has been recommended. This work will require a stamp for building department approval, so hire a structural engineer that has experience in old house work. They may even be able to pare down the size of the sister joists and more than recoup the engineering cost for you.

   ...that's not a mistake, it's rustic

   Edited 5/23/2002 1:10:39 AM ET by Bungalow Jeff