Expert: Bruce E. Johnson - 1/12/2009

Question
Bruce-

We have been living in our home for 3 years now, and I decided to tackle the issue we have noticed in our dining room for quite some time.  The room was obviously added to the home at some point, and is an extension off our kitchen.  The room is on the 2nd floor and also has french doors out to our large deck.  The addition is over top of a patio below, and the only support I can see is 2 circular metal supports (on the far side of the room) that are cemented through the patio below.

Now, to the actual issue.  We have always noticed that the floor was very bouncy.  The previous tenants put in a floating wood laminate floor.  From research, I know these floors would have a certain give, but our issue was to the point where you would walk in the room, and glasses & things on the table would shake.  

I decided to tackle the issue, and we are concerned now to even walk into the room, albeit even sit down and eat dinner.  After pulling up the laminate, there is a subfloor that appears to be in a good shape.  I walked down the patio below and had my wife walk on the floor and could see the floor giving while watching from underneath.  

First off, is 2 support poles cemented in enough support?  I'm afraid to start tearing out the subfloor or the boards covering the frame from below in fear of it turning into a complete overhaul of the rooms structure.  Does this sound like a framing issue, to where we could just increase the number of support boards that were used in the floorings frame?  

I hope this gives you a decent visualization into our issue.  Thanks for your time and I look forward to your input.

Thanks,
Jarid

Answer
Hi Jarid, the support posts are not the problem.  Apparently the span of your joists between support beams is too great for the size of the joist.. If possible you may need to add an intermediate support beam to cut the span of the joists in half.  You didn't mention the size of the floor joists or how far they span between supports.  You may be able to add more joists between the existing floor joists but if the span is too great for the size of the joist then this is not the optimal fix.   I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com