Plywood, Homosote, plywood for train top?

Dwayne B posted:

I am ready to begin my table top for my layout.........Is it overkill to do a layer of plywood then Homosote and then another layer of plywood for the final top?

Yes, definitely "overkill". Simply plywood with Homosote on top is sufficient. When we built our 3-Rail layout, I used only 3/4" roofing plywood, then used Hobby Innovations "Vinyl-Bed" roadbed for only where the track was. End result was very strong, and quiet due to the vinyl roadbed. 

We have this discussion quite often....search can be your friend as we have many topics about this with all kinds of good and immediate information.....

Why put plywood on top of the Homasote?  The reason I used Homasote on top was to kill the noise, putting a hard surface on over it seems to defeat that purpose.

I'll be using foam roadbed and Gargraves/Ross, I'm expecting it to be decently quiet.

I just have a plywood top on my layout with cork roadbed under the track. After I ballasted I removed the screws from the track so noise doesn't get transmitted to the plywood. It's pretty quiet if I run with the sounds off on locomotives.

Most of the noise comes from running at high speeds on hollow, tubular rail. The sound gets transmitted through screws to the plywood. Running trains at slower, more realistic speeds also helps to cut down on noise. 

I'm a bit of a heretic because I use Fastrack on ¼" plywood. Noise problem? Not at 25 SMPH  which is the FRA limit on the Plywood Empire Route

I am a fan of plywood (actually I used MDF) with homasote. No regrets after 4 years.

Thanks for your advice everyone.......It does seem the 2nd layer of plywood is not necessary. I saw a layout constructed this way so I thought this was the norm.

Dwayne, what type of track are you going to use? Hopefully it's good and flat. One problem I ran into with homasote is variations in its thickness and it's inability to grip track srcrews, tight enough, to flatten out long track peices that have a hump to them. My trains looked like they were riding on ocean waves when you watched them at eye level. I ended up gluing down 1/8" MDF over the homasote. Which tiny screws bite into very well. The sound did increase though, like GRJ mentioned, but not by much. I believe if the MDF was cut out and glued down, only under the track, the sound wouldn't have the ability to spread out and amplify, like it does when the whole 4 X 8 sheet is glued down. The problem with the table top layout style most of use, is it's like the flexing skin on a big bass drum head. It amplifies the vibrations above to the sound chamber below. Sounds a bit crazy, but the only way I feel you can totally avoid the table top style from flexing, would be to use corrugated sheet metal first, then form around the edges, then fill it with a few inches of pea gravel concrete and glue everything down.  Or something a little more sane. Simply cut through the table top, along the sides  of the track, to keep the sound isolated and from spreading out into the whole table top.