Bounce In My Floor

Special Eddie

I'M A VIOLENT EXTREMIST!
Feb 28, 2005
1,364
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433
Rockland, New York
#1
I have a bounce issue with my living room floor.
My floor is a 20' x 12' Oak strip floor held up by 2" x 8" x 12' joists at 16" OC and I have full access underneath.

What minimum size beam do I need to install down the middle with only 3 supports along the entire 20' run to get rid of the bounce? I would like the middle support to be 12' from one end.

I'm thinking three or four - 2" x 8" with 1/2" plywood sandwiched, glued and nailed together should be good.

Anybody know for sure?
 
Dec 8, 2004
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#2
Go down to your local building supply... tell them your conditions and they can size a beam/posts accordingly.

I would think you should be able to get away with some LVL or similar....
 

Special Eddie

I'M A VIOLENT EXTREMIST!
Feb 28, 2005
1,364
4
433
Rockland, New York
#3
Thanks, the LVL's start at 9.25" but I'm looking at no more than 7.25" deep.
That's why I would Lam it myself, but I will check with the Lumber yard for options.

edit - I found they do make 7.25" beams, I will look into cost now. - edit
 
Dec 8, 2004
48,667
20,955
693
Maine
#4
If you are worried about height... you might be able to get away with sistering joists to your existing... if you are worried about height... a lot more work obviously.

Also the LVL's you can get up 48'... so a 20' should not be an issue.

And building supply like a lumber place not a home center... as they have computer programs that work with whatever companies LVL product they carry.
 

Special Eddie

I'M A VIOLENT EXTREMIST!
Feb 28, 2005
1,364
4
433
Rockland, New York
#5
I did do the sistering but it had little effect on the bounce. Pissed me off.
I'm thinking I should have glued a piece of 1/2" plywood between them before I nailed them together.
 
Dec 8, 2004
48,667
20,955
693
Maine
#6
Is the plywood tight to the joists? If not go get some trim head screws... predrill and screw down from the top.
 

MetalBender

I like fistables.
Dec 20, 2009
1,308
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198
New Orleans....Iowa
#7
Sister 10's next to the eights. 8" is not floor joists. Simply cut a notch in the ends to set on foundation. Only lose 2" ceiling height and have floor properly supported. If you're putting posts under floor they need a footing under them and not just set on the floor.
 
Dec 8, 2004
48,667
20,955
693
Maine
#8
If you are really concerned about height... I would prob put a steel beam in with a post in the middle with the appropriate footing under the post.
 

CougarHunter

Lying causes cat piss smell.
Mar 2, 2006
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KC Metro
#9
You need a triple 2x10 beam to carry a 12 foot span with 20 feet of width according to the beam span table.
 
Dec 8, 2004
48,667
20,955
693
Maine
#10
You need a triple 2x10 beam to carry a 12 foot span with 20 feet of width according to the beam span table.
He is worried about ceiling height in the basement... that is why I was suggesting some engineered product or steel.