New washer shakes floor!

[tjbaudio]

Hello, the pluming is finally done and the new washer is here! Cleans great but there is a problem. The new washer resonates with the floor and I need to stiffen it! The joist are true 2x8 on 16” centers. with a 10 ft span. The washer and dryer sit on a raised platform made of 2x6 on edge with a layer of cabinet grade oak ply wood (very solid!) This platform is at one end of the joist over the main support beam (8x8) with a post right under the center of the pair. The floor is 1x8 pine or fur with a layer of 1x5 tung and groove pine over that. The washer shakes the floor in front of it and rocks shakes front to back (the direction you would expect with the back being on very solid floor right over the main beam.)

I was planning on adding 2x6 cross bracing between the joist right under the front of the platform and 2 diagonals to the support pillar. I was also thinking of ripping out the tung and groove, re screwing the sub floor, and putting down 1/2” or 5/8” plywood. The rest of the house needs this too I think.

Do you all think I am on the right track?

[Bob NH]

I think you would do a lot of carpentry with little effect.

I would try isolation. Alternatives include:

1. Put some foam rubber under the washer. Get some 1" to 2" foam rubber and a piece of plywood (at least 1/2") a bit bigger than the footprint of the washer. Put 12" squares of foam rubber under each corner of the plywood and set the washer on the plywood. While at it, I might do the washer and dryer together to keep the heights matched.

2. Get some fairly dense foam rubber and isolate the whole platform. Set it on isolation so there are no wood-to-wood contacts or hard fasteners to structure.

[finnegan]

Also, make sure the unit is level.

[Gary Swart]

Not only level, but be sure all 4 corners are solid on the floor. A level might show the unit to be level, but one corner could be not touching. As soon as the machine starts to spin, it will rock and roll. A badly unbalanced load can sometimes cause the machine to vibrate, but that's not an everytime problem.

[tjbaudio]

The unit has been well leveled and all four legs are in good contact with the floor. The shaking is low frequency not a real vibration. I will see what it does after some simple stiffening of the floor.

[tjbaudio]

I Finally got the time to work on the floor. We riped up the top layer of T&G pine to get to the sub floor. It needed replacing any way. The sub floor is random with 8 to 10" wide 1" thick hard wood. I also pulled up one board right in front of my platform to expose the joist. I then cut blocks out of 2x8 just a hair larger than the space so I had to tap them in with a hammer and screwed them in from the sides. This made a world of difference. The original blocks are only 8" away but they are nailed in and not full hight of the joist, only 2x4. I figure they were not helping at all. After that was done I predrilled in the sub floor and screwed down the entire sub floor. 2 or 3 3"screws in each board in each joist. Originally they were nailed about 2/3s of the joist! All in all the floor feels very solid now. We did a load of towels and sheets and even though we could see the drum working to balance the load the floor was shaking about 1/10th as much as it use to. We still have to put down the underlayment. 3/4" bcx should take care of any vibration left.