[JH1]

My floor joists are 2 x 10's spaced 16". The span is 14 feet. The joists, sill plates, beam, piers and block wall all appear to be in good condition. The crawlspace is bone dry and has been for the 4 years I have lived here.

Here's my problem/question:
I just got a new wall-sized entertainment unit with a big TV (finally got the wife to cave in). This unit is in the room in the same direction as the joists - the length of the unit is parallel to the floor joists. The problem is that the darn thing wobbles or bounces when someone walks past it. How can I stop this bouncing?

Sistering the joist is the common solution but I would like to avoid removing the crawl access well and digging a trench simply to get (1) 14' 2x10 into the crawlspace.

Would using strips of 3/4" plywood glued and screwed to the joist be an effective and easier solution for this problem? BallengerB1 offered this solution to a similar but different issue here some time ago. I'm hoping to get feedback from someone who has tried it - if it doesn't work, removing it sounds like a pain if I end up sistering anyway.

Thanks in advance!
Jim

[MOWERMAN2468]

you could sister the joist, or place two 4 x 4 beams perpendicular to the existing joist supported by blocks. But there again, you will be tunnelling.

[hkstroud]

Well, I don't think sistering a additional joist to the one now under the entertainment unit is going to solve you problem. It is the entertainment unit that is bouncing and not the TV isn't it? It might help a little but I have doubts that it will really effect the situation. The vibration is being created out in the room where the person is walking. You do not have carpet do you? It is being transmitted through the flooring and subflooring to the unit. An additional joist would mitigate that some but not much. The unit is probably not completely flat on the floor. It probably has a corner or end that is a little off the floor or at least not carrying its fair share of the weight. I would look at getting as much floor contact as I could with shims before crawling up under the house. Or find some nice area or throw rug to put under it.

[GLEIGHVAH]

Try Posting Up The Joists In The Middle .

Instead Of A 2x10x14' Use A 4x4x2' Or However Tall The Crawlspace Is .

[JH1]

Gleighvah & Mowerman -- I actually considered variations of each of your suggestions. Stacking up blocks to support a small jack and then using a short 4x4 - this would at least let me know if a similar, more permanent solution do the job.

Hkstroud - Actually the room is carpeted but you do bring up an interesting point. While the movement is worse when walking close to the unit (of course) it does sometimes occur when someone is farther away - i.e.. My 10 & 12 year olds bouncing through the middle of the room. Maybe I do need to address more than just the joist or 2 that are supporting the unit (BTW - it's roughly 6.5' tall x 9' wide x 2' deep - solid and very heavy)

Thanks all for the input! Keep it comin' please!

[GLEIGHVAH]

Can You Secure The Unit To The Wall?