Hi all,
So, there's a wealth of information already in this forum about the plywood/foam/Homasote debate. I know this, I've read a lot of threads... but one thing that never gets mentioned is my question above. There's plenty of discussions about Homasote on ply, or using any of the three by themselves. But I've never seen a comparison of whether plywood or Homasote is better to put the foam on.
What I'm trying to avoid is the "drumming" effect that is known to occur with foam, which I'm going to use due to the hilly terrain cut with creeks and gullies I'll be modeling. I want to hear wheels on rails, not all manner of strange reverberations coming from "underground" (no Graboids here...). I've read several threads that say you should glue the foam to a substrate to help avoid the drumming, but I only ever see plywood mentioned. I'm wondering if it might be worth putting it over Homasote instead.
My trackwork will be Code 83 flex glued to cork roadbed, which itself will be glued to the foam. No nails. I will use a 1" and 2" layer of foam, glued together, for the topography I plan to model, and this will be set up on L-girder benchwork.
Based on a number of interesting and highly technical posts (looking at you, Hornblower), I know that a key part of the equation is using a flexible adhesive like caulk between layers. But I'm not sure if I should lay my foam onto Homasote or plywood. Both are available here and within my price range, so those aren't considerations. However, testing both would be cost-prohibitive. So what would be the recommendation? Or is it more to-may-to/to-mah-to considering how I'd be using it (under foam)?
Thanks
- Adam
When all else fails, wing it!
Frankly, I thought my last layout, which had a layer of plywood under the foam, was LOUDER than the one before, which simply had foam glued on top of an open grid frame.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I think we need a sound engineer.
Some say that the ballast glue makes a difference.
Somebody could study this, Model Railroader set Cody on this project.
Homosote is great to stick track nails or spikes into. It is miseably dusty to cut and heavy. It is what I used in the 80's for my first big layout and back then, I had no sound issues, that I recognized.
Thirty years later, my hearing is not what it used to be. 2" of foam on 1/8" plywood and I don't hear the druming. YMMV
Henry
COB Potomac & Northern
Shenandoah Valley
IMO, the drumming happens when trains vibrate the subroadbed. I think there is less drumming when the material is denser and better supported. Its harder to vibrate, theoretically.
My new layout with have half inch ply sub supporting sheet homasote attached by caulk spread evenly by a roller, then cascade products homabed on top of the homasote sheet attached by rolled caulk. Then track caulked onto the homabed.
I'm hoping with two layers of homasote and everything separated by a layer of caulk, vibration will be dampened before it can drum the plywood against the benchwork support.
- Douglas
BigDaddy Some say that the ballast glue makes a difference.
I’ve read that as well in other threads, and Matte Medium is recommended for that reason.
I’m not so much worried about mess. I can deal with that. So far, it sounds like Homasote may be the best option for a base layer.
Doughless IMO, the drumming happens when trains vibrate the subroadbed. I think there is less drumming when the material is denser and better supported, its harder to vibrate. Theoretically.... ...everything separated by a layer of caulk, vibration will be dampened before it can drum the plywood against the benchwork support.
IMO, the drumming happens when trains vibrate the subroadbed. I think there is less drumming when the material is denser and better supported, its harder to vibrate. Theoretically....
...everything separated by a layer of caulk, vibration will be dampened before it can drum the plywood against the benchwork support.
This all makes sense based on what I’ve seen elsewhere, and Homasote is supposed to be denser than ply. Perhaps that would be best then, with the layers of subroadbed, roadbed and track joined by layers of adhesive caulk...
Lonehawk Doughless IMO, the drumming happens when trains vibrate the subroadbed. I think there is less drumming when the material is denser and better supported, its harder to vibrate. Theoretically.... ...everything separated by a layer of caulk, vibration will be dampened before it can drum the plywood against the benchwork support. This all makes sense based on what I’ve seen elsewhere, and Homasote is supposed to be denser than ply. Perhaps that would be best then, with the layers of subroadbed, roadbed and track joined by layers of adhesive caulk...
And, they make concrete kitchen countertops. Why not concrete model railroad subroadbed?
Won't vibrate at all but it would be challenging to wire the layout or install switch machines....
Doughless And, they make concrete kitchen countertops. Why not concrete model railroad subroadbed? Won't vibrate at all but it would be challenging to wire the layout or install switch machines....
True that. But this is why designs in the real world are tempered by practical concerns. Actually, didn't you make a similar point in another thread?
Joking aside, I also recall something in one of those threads (perhaps a comment by Hornblower) saying that while the material density itself was important, it was more the difference in density that regulated sound transmission between materials.
If that's the case, I'd be fine with the ply base, and could use the savings to get better quality wood. If it's not, and the extra density would factor in for improved acoustic nullification, then my earlier surmise that Homasote would be better still holds.
Frak....
Maybe I'll just go to the Big Orange Box near me, grab a sheet of each, and hope my old boss doesn't yell at me for messing with the merchandise...
My instincts tell me foam over homasote should be quieter than foam over plywood, just based on rapping my knuckles on homasote versus on plywood - homasote is softer and transmits fewer vibrations, which are of course the essence of sound.
I also suspect, however, that the differences are not likely to be huge.
One thing to keep in mind is if you ever envision trying to remove the foam. With a spatula and some elbow grease you can do a pretty good job of prying foam up from plywood, even if it was well fastened with adhesive caulk, but homasote tears away in ways that plywood does not: the top layer of homasote pulls up and away from the rest of it. What's left is often too irregular a surface to be usable again, in contrast to the plywood which can be scraped and re-used.
Someone who saw my benchwork (a box like grid of 1x4s with plywood on the top) speculated that it was built like a guitar and might even amplify the sound. In other words their concern was not what the top was, but what was below the plywood or the homasote or whatever.
I have not tried this (which -- heh heh -- doesn't prevent me from urging you to give it a try) but I wonder if the strategic use of rubber washers in the construction of the benchwork would dampen the sound amplifying effects. I can't speak about guitars but know that string instruments such as violins or cellos are considerably quieted if a rubber "mute" is placed on the bridge that transmits vibrations from the strings to the wooden "box" body of the instrument.
Dave Nelson
Homasote over plywood. Foam is awful. I hate it.
Disclaimer: This post may contain humor, sarcasm, and/or flatulence.
Michael Mornard
Bringing the North Woods to South Dakota!
On my layout, I have track on cork on foam, track on spline mounted to plywood, track on spline mounted to open grid, track on cement, track directly on foam and track on a steel stud. The sound changes noticeably as it goes from one to the other.
I have found that what is on the floor under the layout is the biggest determining factor as to the noise level. I had the same 9' x 5' layout over porcelain tile, cement floor, and carpet. The noise level and sound frequency level changed dramatically over each.
DoughlessAnd, they make concrete kitchen countertops. Why not concrete model railroad subroadbed? Won't vibrate at all but it would be challenging to wire the layout or install switch machines....
Cement taught me one thing that I was not expecting, the most noise comes from steel wheels on steel track. Railroading is a loud and noisy business, on cement board all you hear are the wheels on the track, the cement board removes any other noise. You can also cut and drill through the cement board.
I think using foam over plywood is somewhat of a redundant exercise, use one or the other, it certainly makes working through it easier.
My cement roadbed and sub roadbed.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
My layout has large areas of homasote over 5/8" plywood and large areas of 3/4" foam over 5/8" plywood. The foam may be slightly louder but not significantly so. Noise wise, I was astonished how much louder trains are after the flex track is glued down to foam. When the track is just laying on the foam they are nearly silent, but MUCH louder after the track is glued.
But that doesn't answer the OP's question: I don't think homasote is nearly rigid enough to be used as a viable base under foam.
Advantages of Homasote as subroadbed: Very slghtly quieter than foam. Great for spiking track. Doesn't dent if you rest elbow/etc on it. Much tougher surface than foam. Foam is VERY easy to accidentally puncture/dent/etc.
Advantages of foam as subroadbed: Lighter and easier to cut than Homasote, Available in thicker sheets than Homasote. Easier to create negative terrain profiles (ditches, cuts, etc), Normally perfectly flat surface (However I got a couple 1" thick foam sheets that had noticeable bends/swales that were challenging to flatten).
Modeling an HO gauge freelance version of the Union Pacific Oregon Short Line and the Utah Railway around 1957 in a world where Pirates from the Great Salt Lake founded Ogden, UT.
- Photo album of layout construction -
Yeah, I do need the foam to do some negative terrain, so that part's non-negotiable.
But the rigidity factor is something I hadn't thought about. I'm not too worried because I do have a dehumidifier for the train room, but still, it's something to consider. But I wonder how big a factor it would be if I have three inches of foam above it (that's what my topography calls for to do the creeks and gullies), and it's all glued together with latex or PL-400 adhesive. Also, if it was possible for the stuff to buckle and heave in any less than a few decades (barring a flood or an unduly humid environment), I doubt it would be as popular as it is. Who would want to have to redo their trackwork (or entire layout) every few years?
Still, plywood just gained a point or two after these past few comments.
I use a homosote over plywood subroadbed and I like the way it takes nails.
I am not as convinced of it's sound deadening properties though. We laid a layer of Homosote along with other sound deadening material while remodeling the apartment that I eventually moved the layout into and the deadening effect on the downstairs apartment was somewhat marginal at best.
Joe Staten Island West
LonehawkYeah, I do need the foam to do some negative terrain
Use whatever you like, of course. Note that folks used risers with plywood cookie-cutter roadbed to create terrain below the track for decades before extruded foam existed. Including that John Allen fellow.
I would never attempt to use Homasote to add structural strength, but some worries about it getting wet are probably overblown. The company did a test leaving Homasote outside in New Jersey for nearly two years.
Again, choose whatever materials you like and good luck with your layout.
Layout Design GalleryLayout Design Special Interest Group
Wow. That's mighty impressive. So much for worrying about moisture damage.
At any rate, the concern is less about structural integrity/reinforcement and more about neutralizing non-wheel sounds. Any divots I put in the foam will just turn into landscaping opportunities. The area I'm basing on is anything but flat.
I know I should have SOMETHING under the foam to eliminate stray noise, but I've alternately heard that plywood helps or that plywood exacerbates the problem, which is what drew my curiosity to homasote, which everyone seems to swear by for noise deadening and reducing the ambient sound.
Ok, for those of you that have not studied sound, when you use 1x4 or whatever to build a box and cover it, you have basicaly built a drum, period. The only way to stop this effect is to fill in the space though you can midigate the sound by using a sound absorbing material under the layout, like carpet and putting a skirt around it to assorb sound and keep it in the space. Yes you can eliminate most sound but it is very expencive to do, I mean true sound blocking or absorbing material will make most of your engines look cheap. I did experiment once with filling in the space and it did help but not as much as carpet and skirt but this was a fast experiment done without a sound meter, just a test.
I'm going to attack a big myth! Homasote does not have to make a big dusty mess when being cut!
Our club has recently cut a lot of Homasote for our new layout and I have to say that the mess was minimal. The key is the type of blade that is being used. Most blades have a set to the teeth so that the tips of the teeth stick out sideways from the core of the blade. We used blades that were ground to a taper instead of having the teeth bent outward. The resulting mess was easily contained and easily cleaned up. The taper ground blades don't tear at the Homasote. Instead they cut the edge smoothly. There is very little airborne dust and what falls on the floor is easy to vacuum up.
https://www.boschtools.com/us/en/boschtools-ocs/t-shank-jig-saw-blades-for-wood-t234x3-30862-p/
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
My 30' X 16' layout is all L girder benchwork with 1/8" - 1/4" plywood with 1/8 clean corrugated cardboard glued to the top of the plywood with 1/2" to 2" foam glued to that. My track is glued to the top of that. The layer of cardboard acts as a vibration dampener. My layout is very quiet.
Modelling big time 1950's railroading in western Ohio.
Member of the Crooked Rails Model Railroad Club,NMRA and the TCA.
Our club layout is 1x4 framing, with two inch foam set in with caulking. Homasote on top of the foam, then caulked down cork roadbed and then track.
It worked so well in HO that the n scale guys are using the same system.
davidmurray Our club layout is 1x4 framing, with two inch foam set in with caulking. Homasote on top of the foam, then caulked down cork roadbed and then track. It worked so well in HO that the n scale guys are using the same system. Dave
Really? That’s interesting. I had read elsewhere in the forum here that that makes the drumming/ambient noise effect worse. I always thought that would be a preferable approach though. Perhaps the conventional wisdom is not so wise?
Vibration would definitely be a big cause of "drumming", especially if you have a motor hat is not quite "tuned". If it is in your budget, have you considered using neoprene? You could certainly build a test track, using different materials to test sound quality. Build a 3 foot x 1 foot section using flex-track. Use 1/4" plywood, then layer the foam on top, then neoprene, cork roadbed, track.
Wow! I've never been called out directly on this forum before. Lonehawk has again opened the can of worms regarding noise control on model railroads. I am somewhat puzzled when I read so many comments regarding "silencing" our model trains. I have performed quite a few trackside noise and vibration measurements and TRAINS ARE CRAZY LOUD! No, I don't think anyone would desire prototype noise levels on their model layout but I think there is a point where some residual level of noise is appropriate.
Opinions as to how we get to that desired level of noise are as varied as the number of MR subscribers. Hey, if it worked for you, I'm not going to argue with you!
As we don't use extruded foam insulation here in Southern California, I have no first hand experience with the stuff, either professionally or in my modeling. Thus, I can't answer to the various claims that it is noisy or quiet. Although, many here will swear by Homasote, the few times I tested it when used for noise control in multi-family construction projects were not very successful.
Would plywood or Homasote be better under foam? I don't know. However, I do know that plywood has vastly superior structural strength compared to Homasote as the Homasote product was never intended for structural use. Is Homasote less resonant than plywood? Undoubtedly. Will it still support your foam, scenery and trains? With adequate framing support, quite probably. You'd just have to be more carefull not to lean on your layout while working on it. In order for the Homasote to dampen the vibration of the foam, you will need to laminate th foam to the Homasote using some type of "non-hardening" glue (silicone caulking, automotive gasket maker, "Green Glue", etc.). Laminating your roadbed and track using a similar glue will also help. If you don't want your track ballast to "bridge" the resilient glue separation, I would suggest placing a couple layers of waxed paper strips along both sides of your tracks so that the ballast cement does not create physical contact with the foam surface. Once the ballast cement dries, carefully remove the waxed paper to create a slight air space. Any ground cover added after the ballast should use limited amounts of scenic cement so as not to fill the ballast/foam separation gap.
I hope this helps.
Hornblower
hornblower Wow! I've never been called out directly on this forum before.
Wow! I've never been called out directly on this forum before.
Wasn’t calling you out in as bad way. The way you analyze the different aspects of the whole noise issue from a technical standpoint due to your expertise is extremely enlightening.
While I know trains are crazy loud, I’d always had issues with what I consider undesirable noise like motor sounds, grinding gears, and the unrealistically loud “drumming” that makes a single caboose sound like an entire train by itself. I know some of that can be refined out of the equipment itself, the drumming was always the thing I wanted to find an answer to.
hornblower Would plywood or Homasote be better under foam? I don't know. However, I do know that plywood has vastly superior structural strength compared to Homasote as the Homasote product was never intended for structural use. Is Homasote less resonant than plywood? Undoubtedly. Will it still support your foam, scenery and trains? With adequate framing support, quite probably. You'd just have to be more carefull not to lean on your layout while working on it. In order for the Homasote to dampen the vibration of the foam, you will need to laminate th foam to the Homasote using some type of "non-hardening" glue (silicone caulking, automotive gasket maker, "Green Glue", etc.). Laminating your roadbed and track using a similar glue will also help. If you don't want your track ballast to "bridge" the resilient glue separation, I would suggest placing a couple layers of waxed paper strips along both sides of your tracks so that the ballast cement does not create physical contact with the foam surface. Once the ballast cement dries, carefully remove the waxed paper to create a slight air space. Any ground cover added after the ballast should use limited amounts of scenic cement so as not to fill the ballast/foam separation gap. I hope this helps.
Actually, it does. Especially the part about the ballast. With all that has been said here by yourself and others, I think I have the info I need to resolve the drumming/resonance issues. I’m going to use 1/2 inch Homasote under my foam, with everything glued together by adhesive caulk, and also glued to my bench work. I’ll report back on how it all works out Once I have trains running.
Thanks again, everyone. I appreciate all the information.
My layout is 2 inch foam board laid on top of 1/2 inch plywood. The plywood has a 1 by 4 inch fascia edging on all four sides. The 2 inch foamboard is stiff enough to support the trains just fine all by itself. Trouble with foam board is that fasteners won't hold in it. The plywood underneath is there to give me something solid to fasten under table switch machines and wire looms and terminal blocks and all the other things that go under the layout to. The result is quiet enough for me.
Homasote's greatest virtue is that it takes track nails easily and they hold well. It is pretty weak stuff, and it will sag over time. It needs a plywood underneath it to stiffen it up. You don't want to use Homasote to support anthing, cause it won't support diddly. Homasote will deaden sound somewhat. It is noticiable quieter than track laid right down on 1/4 inch plywood. But my two inch foamboard is at least as quiet as Homasote would be.
David Starr www.newsnorthwoods.blogspot.com
Hm. Interesting. Especially the point about warping. I had worried about that, especially as my basement is cinder block and does sometimes “sweat”. I’ll be giving it a good coat of Drylok, but it’s possible that some moisture may still appear. Although, I planned my bench work with 16” centers on the risers. I feel like that, combined with the added stiffness of the foam and a dehumidifier should be enough to prevent it. Otherwise, I’d definitely go plywood. Hm. Maybe I should use a thin ply base under the Homasote.
My benchwork is the same, open grid 1x4's with half-inch plywood on top in most places except where terrain is present.
And yes, I found the flooring surface below had a great deal to do with sound being carried. Apart from replacing stone tile or other hard flooring with 'shag carpeting' to deaden sound, try styrofoam block insulation, cut to fit, inserted into the open box structure below - where it seems noisiest. It stops the 'guitar' amplification you mention to a great extent, and it's easy to do. I also found a curtain on the lower track to quiets things too.
I'll be adding some additional benchwork soon and will give the rubber washer idea a try!
-- "I've often found that 'fixing' a problem is easier than actually 'thinking' about it at the outset. But then, no one's ever rung my phone asking how to split the atom......!"
[/quote]Dan Sanders
Lonehawk Hm. Interesting. Especially the point about warping. I had worried about that, especially as my basement is cinder block and does sometimes “sweat”. I’ll be giving it a good coat of Drylok, but it’s possible that some moisture may still appear. Although, I planned my bench work with 16” centers on the risers. I feel like that, combined with the added stiffness of the foam and a dehumidifier should be enough to prevent it. Otherwise, I’d definitely go plywood. Hm. Maybe I should use a thin ply base under the Homasote.
I would. And if you are concerned about quiet, I'd go with 1/2 inch plywood, it's stiffer and heavier and harder for an HO locomotive to get it resonating. I once did a 4 by 8 from just one sheet of Homasote laid on a framework of 1 by 4s on 16 inch centers. After a couple of years the Homasote sagged inbetween the 16 inch centered joists to the point where I could see the train bobbing up and down as it ran. I think all Homasote needs plywood underneath it.
I cannot speak to homasote. I have 1" foam over 1/2" plywood and have no complaints.
Bear "It's all about having fun."