Maybe this will help you: http://ths.gardenweb.com/forums/load/laundry/msg010912587741.html

I posted that a few weeks ago and we now have our new front loader set installed. We followed the suggestion only used 3/4 inch plywood just under washer. (our washer/dryer is not side by side)
We also put the mat under dryer.
It worked great...so quiet.

Now no one knows that there is laundry being done, except for a very slight hum of dryer and an occasional tiny vibration when an off-balance load spins. I'm still learning how to load it for perfect balance.....:)
If the load is perfectly balanced, we never hear or feel anything at all with the washer, other than a slight pump noise as it fills and drains, which barely lasts anytime at all. Nothing compared to the constant humming of a top loader washer. The dryer in the old set displayed an irritating hum as well, so I decided to throw some mat under the new dryer since I had so much left from purchasing a 4 by 6 stall mat. The mat is extremely heavy.
It is certainly worth $50 to insure the washer will not walk, not to mention the insulation from noise.

Monaw, thank you so much! What a great idea and really not hard to do. Will check out stall mats tomorrow.

macavity, you're welcome!
It's easy to find a tac shop in your area, just Google. I found one within less than 7 miles of my house. Most will carry the stall mats for cridders. Save the leftovers, as you never know when you might need a piece of good rubber! If it is possible for you, you can also wedge a piece or two of rubber between your washer and whatever it's next to near the top of the washer for even more vibration protection of off balanced loads. I was able to do that on the right side of my washer as it is near a cabinet. There's too much space between my w/d to do it on the left side of the washer. Even on the one side it helps for less vibration if my load isn't perfectly balanced.
I got that idea from seeing some guy use those swimming noodles wedged between his w/d and wall.

Here's the video: http://www.youtube.com/watch?v=Y91onCb7nSc&NR=1

Also, don't know if your w/d will go side by side but if so I would have the entire area reinforced and lay one big piece underneath both units. My house is 30+ years and there's a raised platform with a drain for just the washer, so I could not do that without ripping the tile platform out to make it level.

As for finishing off the bare plywood reinforcement, we just left the plywood without tiling/etc, and cut the mat to completely cover the area, and had quarter-round placed to finish the edges. The mat was cut so that it comes right up to the quarter-round, completely covering the plywood.
We can see the mat and although it's by no means a design statement, ... the look doesn't bother us. I guess you could say it has that "industrial" look. :)

Keep in mind that if you cut the rubber so it doesn't show at all to be hidden underneath the units, it might be difficult to place the washer and dryer (especially the heavy washer) perfectly on the mat so that the feet are not falling off the edge of the rubber. Those washers are heavy! Our installers had a difficult enough time getting the washer placed,...I don't see how they could have placed it on a piece of rubber that was cut even to the exact size of the washer, let alone a slightly smaller piece that wouldn't show. I hope I'm making sense here....:)

Good luck to you!

Thanks again,monaw. We were talking today about the actual install, size, etc. Using quarter-round to trim out plywood is a great idea, as well as using a generous size mat. Yes, separating the machines with something (mat,noodle, whatever) is also probably a good idea. Amazing, none of these things is hard to do BEFORE the machines go in. It's trying to fix it afterward that's the real killer.

Haven't decided for certain on washer/dryer brand. Are you pleased with Miele? Don't know why but I've never looked at them. Did you select a particular model based on previous experience? Hope you don't mind my picking your brain just a bit more. Thanks.

macavity, I feel for you as I was in your shoes about a month ago trying to decide! I was coming from a top loader but very much wanted a front loader for all the obvious reasons of energy savings, etc. However, at one point in my search I told my husband that I wasn't going to go for a front loader because I was concerned about mold/second story vibration issues.

Well I then changed my mind back to the front loader idea after doing some more research, and also talking to our Miele repairman about these concerns.

I chose Miele because I do have several other Miele appliances (ovens, dishwasher, vacuum) that are top notch. My mind was open to other brands other than Miele, but I just could not find one that I felt comfortable with. I would rather spend more for something that lasts longer. My feeling is that in the end it will have cost a lot less than "the others".

It will be three weeks next Friday since the install, and I really do love this set! The quality is outstanding. I especially love how quiet they are!
I love saving energy, both for the pocketbook, and the environment.

I don't know if you're coming from a top loader, but there's a learning curb. It is a large drum, and it does have an easier time balancing itself with a fuller load verses a smaller load. With just my husband, myself, and our two doggies, I would have gotten a smaller drum, but I wanted to be able to wash comforters, etc. So I am learning to do fewer, fuller loads than I used to do.
(at 40 plus gallons a crack, I might add...)

Here's a link from a site that answered some questions for me. It's a UK site but not so different from what's going on here in US. I posted this on another thread here but you may not have seen it.

http://www.washerhelp.co.uk/buying-advice-1.html

Monaw, thanks again for some really great information. I will definitely check out that website. Enjoy your new washer and dryer!

macavity, you're sure welcome! I think I forgot to mention that I got the Miele 4842 with the electric 9802 dryer. That's the largest model. My Miele tech advised against the extended warranty. With a certified Miele install, you get two years on the warranty. The install will run around two hundred.

I can't say enough about these machines! I adore them! I didn't get more water programmed into the washer either, and they're cleaning beautifully.

If your pocketbook will allow, I highly recommend. Really they're pretty competitive with some of the front loaders out there in price.

Some guy on one of these threads said his 26 year old Miele is still going strong! I'm hoping I'll never have to replace mine! :) (I'm 54)

Thanks monaw. Will definitely check out the Miele. The extra warranty with certified install is nice and helps a bit. This whole process of seeking the right machine/installation has been so frustrating. Only want to do it once. I had actually almost given up on the planned installation until you posted your experience! By the way, found the stall mats. Sure seems like it should work fine. It will probably be several weeks before I get everything sorted out but now am really looking forward to it! Thanks again for all your help.

Any advice on cutting stall mats? When we went to check them out, the clerk had scary tales of burning rubber and trashed skil saw blades.