I don't know about quieter,

I don't know about quieter, but you can glue the foam directly to the framework.

Thanks, Rick.  My bad in the

Thanks, Rick.  My bad in the subject line - I know the foam can be glued directly to the framework, I meant which is recommended.

Foam drumhead

Foam to be self supporting should be at least 2 inches thick. The problem, however, is that even thick foam without an underlayment will act like a sounding board or drum head and be very noisy, even if you lay your track over cork. That has been my experience.

I believe either on this forum or in one of the Yahoo layout construction forums a rather substantial discussion on quieting foam occurred several months to a year ago. The conclusion as summarized was that any foam, whether 2 inches or 1 inch thick should be laid over at least 1/8 to 3/16 inch masonite or other hardboard by gluing the foam to the hardboard with Liquid Nails or similar construction glues. The interface between two different materials (foam versus compressed wood/paper in the masonite) quiets the drumming effect of the foam. I have 2 areas on my railroad in construction which illustrates well the problems, the first, where the foam is quiet when laid over masonite and the other where 1 inch foam was laid loosely over pine without glue. The latter is very loud; the former quiet.

John

EXCELLENT information

EXCELLENT information, John.  Thank you!  I'll look at putting 1/4 ply or masonite down and then gluing the foam to that.  Should the hardboard be nailed/screwed down or is it better to glue it to the benchwork?

One other consideration to

One other consideration to think about is the possible need for someone to reach in and lean on the foam when working on the layout. I have found it very easy to crush foam with out trying. Because of that I am a fan of more rigid materials like homasote, or masonite over plywood. Another item I am considering for a layout surface was used by Jim Six and that is acoustic ceiling tiles laid flat and contoured with a surform tool. I saw pictures of his method on a website or in a book and it looked very nice. I also suspect it will be much more crush resistant than Styrofoam.

If you do not think you will have issues crushing something the foam should be fine.

I made some measurements

A couple of years ago. It's written up here.

pqe

"Will using plywood on the

    I don't know if it would be significantly quieter but it would be sturdier to have some plywood under there, and it would give something to screw switch motors or blue point controllers to. I doubt that a train going 8 ' 8" is going to be going fast enough to create a noise problem anyway? .....DaveB

More Glue Surface

Hi DSteckler,

I'd go with thin plywood or masonite to increase the surface area of the foam for glueing.

I had issues with the wood and foam expanding and contracting over a five year period...breaking the glue joints where they crossed the wood braces..

I was able to reglue the joints, but there was a lot of underlayout/overhead work.

Thanks, guys!  I appreciate

Thanks, guys!  I appreciate your comments; they are very helpful.

Should the hardboard be

Should the masonite be nailed/screwed down or is it better to glue it to the benchwork?

No need

There's no need to glue the plywood to the frame. In fact it would be a PITA if you need to move a brace for some reason. Screw the ply to the outside frame, and use angles to attach internal braces.

pqe

Thank you.

Thank you.

As far as the question of

As far as the question of whether the sound level difference of open foam construction vs. foam over a solid subsurface is worth it to you, you just need to answer one question.  Do the bulk of your locomotives have sound?  If the answer is yes, then it doesn't matter how you lay your foam because you will never notice the difference.  So, why would you spend all that extra cash on plywood?

Now, if you don't run sound, and/or the noise of wheels on rails really bothers you, then the extra cost of a solid base layer to deaden sound may be worth it to you.  To me, not so much.

Some have sound and some do

Some have sound and some do not.

Foam is pretty loud

Foam without any plywood below it is pretty loud. I've heard it on a couple of layouts, and I know I wouldn't like it. I'd put plywood under it. Regardless of whether or not you're running sound. Actually I'd be more apt to do it when running sound because the sound from the foam is going to ruin the sound from the speaker. 

Randy

Been there, done that ...

I have a 14'x12' N scale layout built on open grid benchwork with 2" foam directly glued to the sides and cross braces.  I also have a 16' staging yard in another room that feeds both ends of the layout and has 1/2" plywood under it.

The sound goes from non-existent on the plywood backed foam to a fairly loud hum on the layout portion with cork and no plywood.  I made a mistake and am thinking about trying to glue some hardwood underneath the foam in a few places to see if it helps and should be done everywhere where I can fit it in.

Jerry

Ready to proceed

Picked up some 1/4" ply at Homers Depot and will be installing this week.l  Next week, foam!