I have a 2nd floor laundry room, and a front-loading washer. In an
unfortunate bit of engineering, my laundry room was placed over my
garage (a 20+ foot span of floor with no support underneath). In the
final spin cycle, you can feel the floor shaking throughout the second
floor, and it's pretty loud downstairs too. I wasn't real worried
about it till I started getting cracks in drywall joints, both
upstairs and down.
After some research (including Google searches of this group), I
thought of three solutions to this problem:
1) Add extra subloor under the washer & dryer
2) Put an adjustable jack post (lally column) directly under the
3) Move the washer to the garage where it can sit on concrete slab.
I have already tried #1. I cut two pieces of 3/4" plywood to fit the
area under both washer and dryer. I screwed the first piece down,
into the joists, using 3" screws. Then I screwed the second piece
over that, down into the joists. It didn't seem to help at all.
Now I'm getting ready to try my #2 solution - the jack post. Here's
where I need advice. My garage ceiling is drywall. After I determine
where to position the column, so that it's directly under the washer,
how exactly should I attach it to the ceiling? Can I just attach it
to joists, or do I have to put a beam up there, and attach to that?
And here's another (probably more important) question: Will this jack
stop my house from shaking? My #1 solution was a complete strike-out,
so now I'm not all that confident in solution #2. I'm thinking that
the (27" wide) washer is sitting on, at most, two joists. If I could
somehow get the post to support these two joists, then it seems the
spin cycle could not possibly shake the floor.
Thanks for any advice.
Use the jack to support a 2" x 12" x 4', placed directly against the garage
ceiling, beneath the washer. Crank in enough force to stop the vibration but
stop short of distorting the floor structure. This WILL stop the house from
feeling the vibration.
In designing a structure, the first consideration is the ability of the
structural members to carry the designed loads. A second consideration,
however, is deflection; although that is more of a useability consideration
as opposed to safety. Your 20' joists are obviously strong enough to carry
the impact forces from the shaking washer, but they are probably at the
limit for allowable deflection. (Relatively new house, right?)
Your adding extra subfloor did little to increase the section properties of
the floor joists, and obviously didn't have much effect as the calculations
would predict. Option 2 should work more effectively because you will not
only shorten the span, but will also move the load over a support. That
will immensely reduce the deflections (and the shaking). I am hesitant to
recommend it, however without knowing the specifics of the construction.
There are several important engineering considerations.
1. The column, if it is to truly pick up the mid span load, would end up
carrying more than half the total load of the joists affected. That's not
just the washer, but everything else in the room along those and adjacent
2. Any member transferring the joist loads to the column should be designed
for the applicable shear and bending stresses that would result.
3. The bearing surface between the joists and the new beam would need to be
adequately sized to prevent a crushing failure of the bottom flange of the
4. The garage slab may not be (and probably is not) adequate to prevent a
punching shear failure. To do it right, you'd need to cut out a part of the
slab & install a real footing. If the garage is not heated, that footing
would need to be down to the frost line.
5. Even if none of the problems above are problems, the floor is still gonna
shake, just not as badly. If you want true isolation from the washer
motion, move the washer.
From a non-engineering perspective, it seems to me an added column in the
garage would be a PITA, but that's just me. Unless convenience is a major
factor, I'd vote for option 3.
Any chance the washer is a Whirlpool built front loader (or equivalent
Sears Kenmore HE3?). I had one with a defective cabinet and it had to
be replaced due to vibration problems. Bottom of cabinet was not
attached properly to rest of it.
Extra braces and extra sub floor thinkness always helps....but one
thing we noticed is if the builder screws down the sub floor in the
main floor laundry room we get less bounce and problems than the ones
that are just nailed down.
Appliance Repair Aid
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