Requesting feedback on idea for foam noise dampening on layout

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chuckfinley

New Member
I've built layouts before but it has been a very long time and I'm picking back up work on a "forever" layout. The substructure is built, and solid. I've had an idea about adhering styrofoam boards as the base of the layout, on top of 1/2" plywood then mounting the layout to this. I'm concerned that when it comes to track that this won't be stable or durable enough and lead to incessant line problems.

The next thought is to sandwich the foam between two 1/2" plywood sheets (there is the space with the backdrop to do this) and still have sound dampening yet a solid foundation for the layout. I've never seen anyone that has tried this, and am not entirely sure how to best secure the layers of the "sandwich" or if I should bag this idea and use other methods for sound insulation underneath?
 

wvg_ca

Active Member
i used a two inch layer on top of 3/8 plywood, the results were good ...
remember to use a flexible adhesive on the foam, i used DAP alex caulking ..
i also glued the track to the foam, again DAP caulking
 
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wvg_ca

Active Member
for best sound insulation, you need to use flexible caulking, but drawback is that DAP is not water soluable like white glue ..[which is very hard, and transmits noise]
 

KB02

Well-Known Member
Most of my layout is track on roadbed (various types) directly on plywood. I have one section that is foam board on a wooden frame, track on roadbed on that. The foam board section is the LOUDEST section of my layout. I don’t know if having the foam ON plywood would may it better, but I definitely don’t recommend using foam only!
 

Selector

Well-Known Member
I have some experience in this. My first layout was built using 5/8" GIS ply in three full slabs mated along their sides to form a huge layout. Yeah, I know, but I wanted exactly that, and didn't have much in the way of problems. Everything ran well, and I used EZ-Track to boot...with 3.8% grades.

I stacked and layered 1.5" carved expanses of foam to create a vast mountain. I carved out the grade on the edge of this mountain. It was a lot of of work. I had a timber scale trestle, scratchbuilt, and another German bridge. The most obviously quiet places on the whole layout were when trains crossed either bridge. You'll find that to be the case. The air surrounding the components of the bridge structure doesn't transmit vibrations well at the frequencies you'll hear from the rest of the 'terrain' you build.

Foam is very noisy. If you support it with joists, stay with 1X4 stood up on edge and wedged between parallel frame stringers, and use PL-300 (safe for foam) to keep it from squirming around on you, you'll find it quite a bit more quiet. Pl-300 eventually dries hard, so the noise will increase. Early on, it stays somewhat malleable, so it will be more quiet.

If you use hardened glue, like many do, say white or yellow glue (they'll both work fine when dry), it will be somewhat noisier because of the hardened glue. If you use a rubbery caulk, it will be quiet. If you have cork or more foam for roadbed to raise the tracks realistically, and use white or yellow, it will be noisy. If you use very thinly spread PL-300, it will eventually become noisy, as I explained above.

So, over/through the surrounding air, as on a bridge, all you can hear is the drive mechanism or the sound system built into the locomotive. Over foam, largely a single expanse, no support, it will be noisy. If you support it, even with a thin sheet of plywood glued below it for either support, or to protect the nether surface , or because you want to mount switch motors and want a harder and more durable surface, it will be more quiet, especially if you use gobs of acrylic caulking.

General rule for acoustics: sounds travel well through single materials. Through composites, not so well. Through two or more monolithic materials sandwiched, very poorly. The idea, if you want to minimize both vibrations AND sound, is to place two different densities of material against each other, flush. Celestron, the telescope manufacturer, used to sell vibration dampening 'shoes', large hockey puck-like things, to place under the legs of their heavy tripods. Users complained that, when they touched the focuser, or even tried to move the scope, it would oscillate or vibrate for many long seconds afterwards, spoiling the view. So, their engineers designed and built these dual-density polymer cups/pucks on which the customer was expected to mount the tripod. It worked surprisingly well. And the same idea applies to sound deadening on the layout. Use different materials, foam and plywood, but soft DAP Alex Plus with Silicone as a fixative between them. Gobs of it, spread a bit, then let the two adhere with some boxes placed atop the foam until the DAP sets.

Lastly, 2" foam, while expensive, will support itself over 6' expanses easily and not sag appreciably over time. If you placed a full paint can in the very middle, all 12 pounds of it, and left it, yeah, that would probably not be so great after a few days, but your structures and trains won't cause that type of deflection.
 

Selector

Well-Known Member
A second post, because if I had kept typing, nobody would read it.

Last point: hardened ballast, and who doesn't like the look of well-groomed ballast once you have taken all the trouble and time it takes to do a good job, is going to be noisy. It need NOT BE noisy if you think in terms of my previous post. Most place roadbed along their centerline, and then they cover it with track lengths, and then they ballast the whole. It is noisy because all that ballast, much of it spilled over to touch the foam or hard-shell scenery next to the tracks, is hard and transmits the vibrations really well. If you want your tracks to be quiet, figure out how to have a wider sub-roadbed, not cork or foam, maybe 1/4" plywood or MDF, and then adhere, with caulk (not any fixative that will eventually be very hard) your narrower cork of foam roadbed. When you glue the tracks, the hardened ballast will be on the sub-roadbed, but there'll be a layer of caulk between that layer and what supports it. I think you'll find that you'll only hear the sounds of the locomotive's decoder amplifier, some clicks of the metal tires running over joints, and the noisier drive mechanisms of your locomotives.
 

chuckfinley

New Member
"If you support it with joists, stay with 1X4 stood up on edge and wedged between parallel frame stringers, and use PL-300 (safe for foam) to keep it from squirming around on you, you'll find it quite a bit more quiet." .... so, when did you place a spy cam in my train room?

I appreciate everyone's help and insights very much. My plan at this time is to add to the setup, which is as described above, an additional layer of plywood above the foam, so it is a foam sandwich on plywood toast. The roadbed materials I have are, I believe, recycled rubber.

My hopes are that track laying on rubber, then plywood, then foam, then plywood will be both stable and quiet. If not.... then I guess it won't be, but I'll have made every effort at it.

An upside of a base like this will be that the main flat section could be excavated into for depth, so to help further contrast the areas of raised grade which are planned for the middle and opposite end section.
 




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