span length for reinforcing floor joists

Reply

  #1  
Old 11-17-07, 11:24 AM
K
Member
Thread Starter
Join Date: Nov 2007
Posts: 5
Received 0 Votes on 0 Posts
span length for reinforcing floor joists

Hi everyone,

I am remodeling a recently bought home. One of the upstairs rooms is a game room and I plan on putting a pool table in it.

The original floor joists were 2x6 16" OC - I glued and nailed another joist on to existing joist - so now it is 4x6 14" OC. If I would add another joist in between, that would make the joist system 2x6 8" OC.

I want to know which one would be better to try.

How can I find out since there are no calculators I can find online that will allow me to get the appropriate spans as a function of sistered 4x6 joists or at a spacing of 8" OC?

The thing is the former owner added a second story, but did not reinforce the 2x6 ceiling (floor for the 2nd floor) joists. He simply laid 2x4's perpendicular to the "ceiling" joists 16" OC and used a single layer of tounge and grooved 3/4" floor boards. Upon inspection there are many places where the crossing 2x4 do not even tough the underlying joists.

The rest of information: Southern Pine grade #2; dead and live load of 10 and 40, respectively; deflection of L/360.

Maybe you could help me with an exact answer or tell me where should I look to calculate myself.

Thanks in advance!
 
Sponsored Links
  #2  
Old 11-17-07, 01:13 PM
I
Member
Join Date: Aug 2007
Posts: 24
Received 0 Votes on 0 Posts
  #3  
Old 11-17-07, 01:17 PM
K
Member
Thread Starter
Join Date: Nov 2007
Posts: 5
Received 0 Votes on 0 Posts

it is not for 4x6 dimensions......that is what i was trying to explain in my post......
 
  #4  
Old 11-17-07, 03:10 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,967
Received 6 Votes on 6 Posts
You double posted, and are getting answers in both forums. It only tends to confuse us when you do that. Try to consolidate your posts. We read 'em all, so we'll pick up on it.
 
  #5  
Old 11-17-07, 03:21 PM
K
Member
Thread Starter
Join Date: Nov 2007
Posts: 5
Received 0 Votes on 0 Posts
Originally Posted by chandler View Post
You double posted, and are getting answers in both forums. It only tends to confuse us when you do that. Try to consolidate your posts. We read 'em all, so we'll pick up on it.

I am sorry - I am new here. I wasn't sure in which one of the forums my question would fit better. Besides, I did not think that people would read all forums, so I just wanted to increase my chance in getting an answer.
 
  #6  
Old 11-17-07, 03:52 PM
Join Date: Mar 2005
Location: USA
Posts: 6,130
Received 0 Votes on 0 Posts
span length for reinforcing floor joists

Just one thing about sistering joists even if you do the connections right (which is difficult at best).

If you do not raise the original joist, when you add a sister, it is not carrying any load and the original joist still carries all the dead load.

The new live load will be carried by both josits at best. You will never do as much with sistered joists as you would do with the same amount of joists originally installed - especially when it comes to deflection (pool table?).

Your old joists will have some permanent deflections built into them (creep is the engineering term).

Also, your "4x6s" are really not equivalent to real 4x6s (3.5x5.5) since they are only 3.0x5.5".
 
  #7  
Old 11-19-07, 06:00 AM
OhioDraft's Avatar
Member
Join Date: Oct 2007
Location: SW Ohio
Posts: 157
Received 0 Votes on 0 Posts
Your game room is probably above the garage am I wrong? That is irrelevant I suppose, more than likely your 2x6's are part of an attic truss, the 2x6 being the bottom chord. I know this because no one would build a floor system of 2x6's, let alone on 16" centers. That means the effective span of the 2x6's is the width of the room, as the walls of the room help support the floor members. Basically you need not reinforce the 2x6's because these spaces are usually designed knowing that it may be finished off later.
 
  #8  
Old 11-22-07, 06:16 AM
C
Member
Join Date: Feb 2006
Location: New York
Posts: 174
Received 0 Votes on 0 Posts
You don't say what the span is. We just finished an addition with a pool room that was 14' across. It was framed with
2x10 joists 12" o.c. If I were you, I would speak to an architect or engineer. It may be possible to install some type of engieered girders (LVL, paralam, flitchplate, etc.) at the locations in the floor where your load points are going to be from the pool table.
 
  #9  
Old 11-22-07, 07:46 AM
K
Member
Thread Starter
Join Date: Nov 2007
Posts: 5
Received 0 Votes on 0 Posts
The span is 13'. Someone gave me the idea of OSB.

I had a structural engineer coming - he recommended sistering saying that that would avoid twisting. But he did not recommend blocking while I would do that.

Thanks a lot,
kyra
 
  #10  
Old 11-25-07, 03:35 PM
S
Member
Join Date: Nov 2007
Location: Baltimore, MD
Posts: 61
Received 0 Votes on 0 Posts
Personally, I like Craig 845's suggestion to beef up under the load points of the table. Unless you sheet with 3/4" ply and then 3/4" hardwood, or something similar, you'll want something solid under the feet anyway I'd guess. How heavy is this pool table?

Steve
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: