02:11AM | 10/19/02
Member Since: 10/18/02
1 lifetime posts
The floor in the family room of my house has too much bounce to it. You can feel when someone heavy walks across and things will rattle. Looking for some advice on best way to remedy this.

The details: The house is 4 years old. The floor in question has a 16 foot span and the floor joists are 2x10's on 12 inch centers. OSB subfloor, I don't know how thick. There is cross bracing, but I suspect not enough as there is only one set of cross bracing approximately in the middle of the span.

I have access to the entire underside from the basement so can do pretty much anything except add a support column (I want to use the open floor space below for a pool table). I am planning to have the basement area under this section finished and expect to do that in a couple months so I want to make sure I address the floor bounce issue once and forever before that work is done.

Some options that are being considered:
(1) Additional cross bracing or perhaps solid blocking at 4 foot intervals.
(2) Rip 3/4" plywood to width of joist and sandwich on each side of joists to add stiffness to the joists, maybe only in the middle of the span.
(3) Glue and screw 3/4" plywood sheets to the bottom of the joists in the center of the span (i.e. a subfloor on the bottom of the joists).

The last one was suggested by my brother-in-law. He sometimes does things in a bit unconventional way but he always seems to get good results. Contractor I talked to said he'd never seen it done but was "worth a try".

So, any experiences or advice on solving this? My objective is to get the best result I can, I don't mind spending some extra time and/or money on it to get the best results but don't want to waste my time on something that will have no impact.



04:55AM | 10/21/02
Member Since: 03/13/00
1675 lifetime posts
I vote for number 2, using bolts rather than nails or screws.


11:19AM | 10/23/02
Member Since: 10/15/02
359 lifetime posts
16' steel plates on every other joist would work also. Saw that done on an old house segment.

j Xynn

05:01PM | 12/19/02
Member Since: 11/29/02
6 lifetime posts
I've an 1860 farm house, with ceiling/floors that are like that. I didn't want to use 2x12's to stiffen so I purchased flitch plates. 1/8" plate steel that was 14' long by the 9.5" width of the old joists, and placed a 2 by over it, and bolted it together on 8" centers, near the top and bottom. It removed the bounce wonderfully.... Of course the fix is neither easy, nor cheap....but by worked. When someone jumped things would fall off the top of the dresser, now, the bounce is perhaps 1/10, and totally adequate.


11:18PM | 12/25/02
Member Since: 10/15/02
359 lifetime posts
Yep the steel plates work like a charm. I have to do something like that with my main beam in the basement. they are made out of 4 2x12's and some brainless boob decided to install a pocket door directly underneath it, and int eh proccess chewed out a huge chunk of at least 3 of the boards, I wont know how bad it is until I gut the basement next year, they drywalled the entire area.


06:06PM | 12/28/02
Member Since: 11/06/02
1281 lifetime posts
The steel plates will do it as will ading TJIs or LVLs but the cheapest way to improve this is to add strapping at 16"oc to the bottom of the 2x10 joists, perpendicular to them.

Adding the ply to the sides of the existing joists will do next to nothing. The strappin will do similar to adding a plywood sheet snadwhich to the bottom but more easily and less expensive.

I've also seen a couple time where engineers recoimmended adding a continuous 2x4 directly to the bottom of the joist with glue and nails to turn the joists into I-joist affairs.



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