Floor joists moving under entertainment center

[John]

I've recently moved into a 20-yo ranch home with a generous crawl space (more like an unfinished basement). After I moved our massive entertainment center into the living room I've noticed that the floor around the ent. ctr. has become flexible enough to where any adult can walk near the it and the entire ent. cntr. shakes. From below I can see the floor joists flexing downward slightly when my petite wife walks in the area. There are metal braces installed between the joists, but they don't seem to help in this regard.

So to conteract this I have nailed two 8' 2x4s to double the floor joists under this area, which may have helped a tiny bit, but not much. I have considered adding a series of vertical 2x4s or 4x4s under the joists that serve as load-bearing pillars under the joists, but I don't want this to look like I've cobbled together some amaturish solution to the problem. To be more specific, I don't want a potential buyer to see the posts and think that the floor is weak in that area, because I don't think it is weak. It's just holding a big load in a high traffic area.

Any advice on how to fix this without creating some sort of Rube Goldberg would be greatly appreciated!! :)

John

[James Owens]

I would use temporary jacks to re-align the existing joists, and then generously nail some 2 x 8 or 2 x 10 joists (whichever fits) onto them. The additional joists should be long enough to rest on a sill or vertical support at both ends.

As for adding posts, there is no shame in using permanent jackposts if the crawlspace is not used for anything but storage. I'd rather buy a house with those than one with a sagging structure and cracking walls. Besides, if you use metal jackposts, then if you ever move the entertainment centre you can just take them down.

-- "For it is only of the new one grows tired. Of the old one never tires."

-- Kierkegaard, _Repetition_

James Owens, Ottawa, Canada

[Edwin Pawlowski]

I'd run a cross beam and put a post under it. That will do more to support it properly than any other cobbled together solutions. Simple, neat, and will support a LOT of weight.

[Joseph Meehan]

Also make sure it is sitting on a good concrete pad.

[Jeff Wisnia]

Is that the only part of the floor which does that, or do you just notice it more because a door or something else on the entertainment center rattles when she walks by?

I don't see why just adding weight to one part of the structure should make it become more flexible. Have you tried looking at other joists down there with a similar unsupported span to see if they "give" a little too when wifey walks on top of them?

I ask that because the doors on the "highboy" dresser in the second floor master bedroom of our home rattle a little when I walk past it. That's the only indication I get that the floor isn't totally rigid.

The highboy's doors have spring catches with a little bit of free play in them and I guess the piece is so close to being level that gravity doesn't have much effect on the doors, so just a little bit of shake makes them "talk".

Someday I'm gonna screw a couple of magnetic catches in that piece of furniture to stop the rattle. (Course I've been thinking about doing that for at least 20 years now.)

Jeff

[ameijers]

What he said, but before you go to that expense, make sure the cross braces between the joists (the 'X' things) are in place, and nailed on bottom end. Makes a difference sometimes. If you dont have any, add some. I think they still sell the metal ones that can be added from below after floor is decked.

aem sends...

[John]

How about a cinderblock tightly embedded in the ground?

Thanks, John

[John]

Thanks for the response! Yes, I believe the cross braces are properly installed-- I temporarily removed one to nail up the 2x4.

John

[John]

My wife has a collection of decorative glass dinnerware in the center that rattles big time. When I walk through the area in question I can feel the floor joists sag a little. This didn't happen when we didn't have the ent. center there. I've been walking through the area for three months and not noticed a problem until we moved that thing in.

There's no other area that has anything as massive as the ent. center, so we don't know if it is a problem in other areas.

It doesn't take much to get the glass chattering in the cabinets, but I'm less concerned about that than the sagging joists I notice when I walk across the area and the sagging I saw from the crawlspace when my wife was walking over it. We're not big people so it's not a bodywieght problem. The ent. center is solid wood with a large TV in it and two solid wood and glass display cabinets on either side. It is about 7' tall and 5' wide. Our previous home sat on a slab, so we've never had this problem before.

Thanks for the reply!

John

[Joseph Meehan]

I would want a real footer of poured concrete. Cinderblock sitting on the ground is not my idea of a solid foundation and without a solid foundation, you will not get support for long. Remember to have an adjustable jack, it may need a little adjustment after a while.