Sound deadening materials

I'd like to add a question but don't want to hijack your thread so please excuse me.  Does it reduce noise by placing sound deadening material inside box cars or beneath the loads in hoppers or gondolas?  John in Lansing, ILL

IMHO, 3/4" plywood is overkill and not necessary. You should be able to use 3/8" - 1/2" with no issues, including being able to stand on it, if necessary, especially if you're building on 16" centers.

The foam sheets you are referencing are typically 3/4" or 1" thick semi-rigid 4' X 8' sheets sold at HD (pink)  or Lowes (blue/green). There are also 2" thick foam sheets which some people use as the base, itself, but that is not what you'd be in the market for.

I've never used homasote or Woodlands roadbed before so I can't answer your other questions.  I have used a 1/4" thick soft foam made for Fastrack and sold on the bay, which is fairly quiet when placed over wood and/or semi-rigid foam. 

Richie C. posted:

IMHO, 3/4" plywood is overkill and not necessary. You should be able to use 3/8" - 1/2" with no issues, including being able to stand on it, if necessary, especially if you're building on 16" centers.

The foam sheets you are referencing are typically 3/4" or 1" thick semi-rigid 4' X 8' sheets sold at HD (pink)  or Lowes (blue/green). There are also 2" thick foam sheets which some people use as the base, itself, but that is not what you'd be in the market for.

I've never used homasote or Woodlands roadbed before so I can't answer your other questions.  I have used a 1/4" thick soft foam made for Fastrack and sold on the bay, which is fairly quiet when placed over wood and/or semi-rigid foam. 

 

Richie, 

I have the plywood already left over so while overkill yes, it is available. Will allow me to reduce substructure too. I actually have urethane sealing foam in a roll from another project that I thought may make things quieter.  Would like to get opinions, as I know what tubular and fastrak sounds like on a bare sheet of ply and it is annoying to say the least. Fine for the Christmas Village, but.... want to do this right.

Sound considerations IME:

Sound is usually based in movement with vibration/friction.  Any panel which reduces or eliminated movement will attenuate the sound.  I found Advantech 4' X 8' X 3/4" is the best for sound control.  Available thru 84 Lumber and other non big box building supply stores.  Approx. $30. per sheet.

Tubular rail is louder than solid rail.

Hollow plastic built in road bed acts like a drum, loud.

2 rail trains are much quieter than three rail trains.

Signature scale 2 rail switches are quieter than Atlas 2 rail switches with wider frog clearances.

The best sound deadening I have found is to run your trains at scale speed.

Homosote likely would be more sound deadening over plywood. Some people cut the homasote into being roadbed, bevel it and then ballast the track, others will cover the entire table with homasote (which allows you to do things like, for example, cut out the homasote to 'sink' buildings down below the surface layer). On my layout growing up I had ceiling tile on the table, worked pretty well and is usually a lot more available than homasote. Sometimes people will use a sandwich of cork/rubberized roadbed over homasote, which further will reduce sound. 

The key thing is to try and isolate the track from the plywood, don't screw the track through whatever substrate you use into the table. My opinion, for what it is worth, is to glue whatever you are using to the plywood, then ballast the track using a binding agent (usually white glue in water with a tiny bit of alcohol), which will secure the track to the roadbed. This should help isolate the track from the plywood, and help deaden the sound.

With the layout I am attempting to build, I am using 4" of foam over plywood to allow me to more easily do below track features, and I'll likely use some form of roadbed, too, I have heard that foam isn't particularly good at sound deadening. 

Because I am a cabinet maker of well over 40 years and have total access to a well equipped shop with discounted materials, I have built a fair share of layouts.  I have tried acoustical sound board, acoustical caulk, polystyrene, convoluted foam and homasote on 3/8” , 1/2” and 3/4” plywood.   The bench work can act like an acoustic guitar and so can your rolling stock.  Lee Willis did an extensive study and found that sound deadening material placed in rolling stock can reduce the decibel level considerably.  The thickness of the plywood did not seem to make a huge difference although the more ply count seems to help. Sound travels along the grain, so thinner ply and higher count does seem to reduce sound transmission.  The best results that I have achieved were using 1/2” Baltic birch plywood with 1/2” homasote ( the real stuff, not the builders board) and homasote roadbed.  Yes that equals 1 inch of homasote.  Then after the wiring is finished place convoluted sound absorbing foam under the benchwork.   The only expensive part is the plywood, which is about 2 to 3 times the cost of bcx pine.   Polystyrene ( pink or blue ) does not seem to reduce the sound but it is nice for creating landforms. The type of track does make a difference with the plastic roadbed being the loudest and Atlas being the most quiet.  There is a product called resilient Chanel which stops sound transmissions dead in there tracks but it is only sold by the case and only wholesale. I have used it once in a commercial application and it is amazing.

Awsome information Gentlemen. Might see about the resiliant channel but definately will use homasote... you are not close enough to get ya to help me out with your discounts are you???😆

Definately will run scale speeds!

I have good results with plywood, foam board, and topped with ceiling tile using Fastrack. Don't know what is meant by running at scale speeds, as 60 smph sure is a lot louder than 20 smph. I run trains at 20 smph, and my db app reads 65 or 66, which is normal conversation. At 40 smph it reads high 70s, which is heavy traffic. I like to run slower because there is less repetition.