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Doug Miller

In article , wrote:
We have a Whirlpool Gold Catalyst Three-Speed Electronic Washer Model
No. GSX9885JQ1, Serial No. CP4602130 installed in April 2003. On the
clothes washer's slowest spin cycle, vibration radiates out to 15'
enough to loosen drywall screws and cause moldings to separate at
seams. On the regular spin cycle, the vibration is awful.

I suspect structural conditions in the home, rather than the washer. That's a
hell of a radius. Perhaps the washer is vibrating at, or close to, the
resonant frequency of some component of the structure.

The problem was obvious immediately. The dealer returned to check the
installation and leveling and said it was OK. Then we had a Whirlpool
service call and the technician said the machine was operating
properly.

The house was completed in April 2003. The 3,000 sq ft ground floor
is supported by an 8-course block foundation and TJI's over a crawl
space. The laundry room and clothes washer is located in an area
resting on an 18' TJI span supported on the foundation at each end.

That's a pretty long span! How deep are these joints, and how far apart on
center? Is there any bridging to brace adjacent joists against each other?

To damp the vibration, we braced one of the two TJI's right under the
washer with a 4x4. There is some improvement but not enough. We are
looking for more ideas as to what can be done.

If bracing one joist helps, it stands to reason that bracing two joists would
help more.

Should we try installing additional bracing under the TJI's in the
location of the washer: more 4x4's, several permanent jacks, concrete
block columns, etc.?

That would be my first step, yes -- 4x4s spanning not only the joists under
the washer, but also one more joist to each side, with jacks underneath. See
if that helps.

If my guess about resonance is correct, you do *not* want to put the 4x4s at a
distance from the end of the joist which is any integer reciprocal (1/2, 1/3,
1/4, etc) of the joist length, because the resonant frequency of such segments
would be merely the second, third, fourth, etc. harmonics of the resonant
frequency of the entire joist.

So for an 18-foot span, don't put your supports at 9', 6', 4'6", 3'7", 3',
2'7", 2'3", or 2' from either end.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.