Scramblur wrote:
Hello all,

I just setup a new entertainment center in my home. The home is from
the 50's and has wood floors. The ent center is big and heavy. When I
walk through the entrance way, that is about 4 feet from the ent
center, stepping on a certain area, about 2 square feet in size, causes
the entertainment center to shake. The unit is not off blanace, I
cannot shake it by hand myself, but if I was to hop in this one area,
the unit shakes a lot. Even when my 35 lb dog walks thorugh this area,
the system vibrates a lot.

Any suggestion as to what is going on here and how I can possilby fix
it?

Thanks in advance.

Steve

Steve-

This is a classic problem with larger heavier modern furniture.

Long winded answer..........

Your floor system is not infinitely stiff (no residnetial one is)

when one walks on the floor each foot fall is like a large deadhammer
blow, the floor deflects from this force, changing shape slightly

So you have a large tall piece of furniture mounted on the same floor
system, when floor deflects it also deflects under the front of the
unit. I assume the back of the unit is against the wall. Since the
unit is tall (about 3+ times taller than its shortest base dimension?)
it "amplifies" the motion that it gets at its base by this ratio.

Depending which way the joists run that can make the problem
worse.....I'm guessing that the joists run in the same direction as the
long dimension of the unit?

Making the floor system stiffer will reduce the problem.

Other have suggested shims, screws, "sistered" joists, blocking to
share load, etc.

BTDT......these all can work but they can be a lot of effort

If it was my house & the chances of reloacting the unit were small I
would:

"survey" floor....that is jump in various location to find ALL the
points that give you the undesired behavior.....hopefully only one or
two.


I'd install a jack post at each location.....very high added stifness,
quck & easy if slightly inelegant (but better than the rock idea)

II have four adjustable jack posts sitting in my garage but I cannot
find a link for them

there are close so you'll get the idea

http://www.loghelp.com/screwjacks.html

cheers
Bob