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I use 1/2" (15/32") plywood underlayment in fir only.  Many years ago, the product was referred to as PTS for "plugged, touched, and sanded. or "Underlayment C." A couple of the higher quality lumber yards in my area usually carry it.  It's stable and should be fine for 24"  OC as someone mentioned above.  For those standing on the table, I suppose weight load plays a role  I'm waiting for the price to come down before I buy another four sheets for the addition to start hopefully this coming winter...my usage of this product is personal preference only.  CDX or even OSB (waferboard) should do the trick also...

It appears that we've collectively concluded that there are two choices here, Baltic birch or B-C.

Unfortunately, following the this thread from the beginning, there have been many more  suggestions that are at least worth considering.

As with most everything though, on this fine forum and in our hobby in general, there's clearly no concensus.

What I saw here was an initial question about what to use, or at least consider, in place of pricey plywood.

And in the end the answer turns out to be nothing -- suck it up and spend the money on the plywood or you'll have dire consequences.

I feel sorry for newbies in the future who end up stumbling across this thread.  Despite the best of intents it looks like we have generated more confusion than substance.

How does this happen?  And apparently so often?

Mike

Last edited by Mellow Hudson Mike

Of all the sheet products I can think of with reasonable structural value and moisture stability used in typical basement areas, plywood or OSB (waferboard) come to mind. Foam products, gypsum products, hardboard products, or other building materials available in sheets, offer little or no structural value.  It's plywood or OSB (cheaper) that take the prize.  Sorry to say that prices are up across the board on building products, but they will come down substantially, in my view, when the supply situation adjusts to normal production levels.  I recall other times in our economy when prices dropped like a rock, but yes, this time the situation is somewhat different because of lock-downs.  Most commodity plywood sold in the USA is manufactured domestically and not subject to offshore whims and container issues.

Other wood alternatives are  lower grade 1 x 6 or 1 x 8 pine boards...my first layout had them exclusively with no issue at 24" OC.   This inflation thing is a real problem, but I'm waiting it out to buy my preference...   It seems in most cases on the forum, contributors express their good will views for a reason, and  I believe most of us have benefited by the wide variety of comments and opinions.  I recall being a "newbie" here several years ago and I credit this forum for the majority of my knowledge in building my initial layout, especially, and even more so now on my second layout..

Last edited by Capetrainman

Mello Mike,

    Personally, as a newbie on certain topics, I love reading threads with many many points of view.  The reason is that depending on the circumstances of the project, such as size, weight, heat, light, moisture, expense, and product availability, there is not really a perfect solution that will fit each and every situation.

  Plus, by hearing all of the different solutions and supporting arguments, I learn a lot from you guys!

Thanks,

Mannyrock

I started a similar fire on another thread referring to this discussion. After analyzing all the opinions, I'm going with 1/2" Baltic Birch under Homasote. Please- no cautions or lectures otherwise; that is the way it will be. There is a local plywood supplier here that has what I need for the usual crazy price, and it is what it is, period, dot. Thanks again, GRJ!

Very wise decision 452Card.  I am a Journeyman carpenter who has been building custom cabinets for 44 years. There are so many variables in each application that it is best to err on the side of caution. The size of the layout, the humidity and above all the materials used in the structure that the plywood will be fastened to are all factors that affect the movement. The most stable sheeting will be apple ply and then Baltic birch but MDO with the overlay on two sides is very good also. O gauge is a very forgiving scale and as so we can get away with inferior materials that smaller scales would not accept.  One suggestion though is to use the same materials for the superstructure that you use for the decking, that way expansion and contraction is consistent throughout the layout if the humidity is not stable.      Some of us look at our benchwork as cabinetry and some just want to run trains.  No right or wrong, just whatever makes you happy.  

@452 Card posted:

I am very fortunate to have a climate-controlled second floor room for the layout, so humidity is not much of a factor in my decision for the material. Also, because the benchwork is Mianne I don't have to be concerned with sagging between girders. My main concern is noise abatement.

I'm curious why you think that Mianne benchwork makes you immune to sagging benchtop material?

452 Card.   If your main concern is noise, the homasote will make a huge difference. Then when you are done with the wiring, purchase a roll of convoluted acoustic foam. Fasten to the underside with pushpins and your layout will be whisper quiet, remember to face the convoluted side up.   The majority of the sound is created inside the benchwork just like an acoustic guitar. The foam will absorb the sound like a sponge to water. If you need to get to the wiring, just pull the pushpins and fold the foam out of the way.   In a controlled environment I have never had to seal anything and if stored properly I have yet to see  Baltic birch warp EVER.  

@452 Card posted:

How much sagging, if any, can occur with BB over 2x2' squares? I think none. The worst risk is the 2x3 sections in the middle. Again- this layout is in a climate controlled room. I plan to attach the base material using steel L-brackets. so the assembly should be as a unit that will not sag. What is your benchwork?

My benchwork is Mianne base and Baltic Birch top with Homasote over it.  No sagging with Baltic Birch, and none expected.  The Homasote makes a huge difference in the sound suppression.

My layout is 31 x 21 feet, in an L shaped configuration, with two interconected levels. It uses an inverted L girder construction. The legs, stringers, girders (16" centers) and risers are all made from 1 x 4 poplar.  The sub roadbed is made from 3/4" 13 ply Baltic Birch plywood. Nothing has moved, warped, swollen, or changed shape since I put it together in 2006.

If I had to do it over, I would build it the same way

Last edited by John Sethian

Keith-

Is convoluted acoustic foam the stuff that is on the walls in studios? If so, I would use insulation installation rods to hold it in place. Easy to remove and replace if necessary. Wait....

Ah, found it online. Also called eggcrate foam, the stuff they use in gun cases. Available in many sizes, including 4'x8'. Great idea, eliminates the fibreglass stuff and all its badness.

Last edited by 452 Card
@452 Card posted:

Keith-

Is convoluted acoustic foam the stuff that is on the walls in studios? If so, I would use insulation installation rods to hold it in place. Easy to remove and replace if necessary. Wait....

Ah, found it online. Also called eggcrate foam, the stuff they use in gun cases. Available in many sizes, including 4'x8'. Great idea, eliminates the fibreglass stuff and all its badness.

With noise, number of observations/thoughts. You are really fortunate with your train room, that is an amazing space. One problem you may have is echoes in the space, any noise the layout generates it is going to echo in that space. Things like posters on the wall, furniture, curtains on the windows would help to stop that from happening.

The other thing you might want to think of is with the hardwood floor you might want to put some sort of isolating material between the legs and the floors, because any vibrations on the table will be transmitted through the legs to the floor, and that will create noise. Something like the rubber cups they have to put under table legs, or a small square of foam rubber.

And yep, homasote or ceiling tile on top of whatever base material you use is a good idea, and as has been discussed on here when putting down track attach it to that material, not the underlying wood.

The egg crate sound deadening material under the layout might work as well, never tried that one.

Hope this was helpful, love to see how the layout comes out.

Big kid is correct about the hardwood floors, a few area rugs will help considerably.  He is also correct about some type of sound damper between the legs and the floor, this is really important and will be much easier before any additional weight is placed on the benchwork.  I purchased a couple of commercial carpet tile with a thick and dense rubber backing which I cut into 3” x 3” squares. I placed these under the legs, unfortunately after the layout was built.  Wish I would’ve done this during construction, it would have been a lot easier.

Trains running with sound turned off to determine Decibel Level of the layout construction.

6 trains and 54 cars.  Plywood, Homasote (Sound Board), Foam Roadbed, Atlas Track & Turnouts (about 40db)  Normal conversation about 65db.  Speed 25% (Legacy speed steps @ 50)

Hmmm.  This discussion has gotten very interesting.

Whenever I stand within 100 feet of a passing train, the ground rumbles, the wheels clatter and the rails sing.  It is very loud, almost deafening,  and it is what makes trains exciting.

So, for all of the folks who are high sticklers for realism, why all of the massive efforts to suppress the sounds of your the trains?   To me at least, that makes it very unrealistic. 

When a real train passes, can you hear the voices of the men inside, or all of the other dozens of little sounds or noises that may come with all of the latest computer chip command control engines?  Nope.  I lived two blocks from a trainyard in Memphis for about 3 months, and I heard all of those sounds from real engines and cars, but only when they were traveling at a crawl through the switching yard.

Foam track bed on heavily glued and screwed plywood is what I have, and it dampened the "hollow drum" sound enough to be realistic for me.

So, are you building your table top beds with highly suppressed sound for realism?  Or, to accommodate all of the sound features of the engines you are buying?  (Which kinda seems backwards to me.)

Just something to think about.

To each his own of course. 

Mannyrock

Manny-

While I kind of liked the noise of my old post war layout, which as a kid I loved to sit under it and listen to the trains go overhead, it is kind of like having the smoke unit on on the engin, comes down to personal choice. It could be people simply prefer quiet, or want to hear the engine sounds, or maybe they are one of them weirdos that has a amp  that goes to 11 instead of only 10 and they have it at 1 playing classical music *lol*. Especially with a layout upstairs in the house, maybe they don't want to disturb others.  Me I am not that worried about the noise, I kind of like the clickety clack and roar and whatnot, and if I listen to music, make sure it is beethoven with the music he wrote when he was angry and turn the amp up

Keith, BigKid et al-

Look closely at the bottom of the legs on the upstairs layout. Each leg has a 3" black floor slider to make moving the assembly easy. I still have to install the backdrop, so moving the assembly is necessary. When the plywood is installed it should make the whole unit easier to move. I hope to acquire the plywood this Thursday.

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Now, on to the noise topic. In a former life I was a locomotive engineer, so noise is nothing new to me. I have a 4x8 layout in the basement that is 1/2 AC ply with MTH RealTrax, nothing else under it. The noise is so obnoxious that everyone is yelling to each other while the postwar stuff is running. This cannot happen on the new layout, so I am endevouring to keep it to a minimum.

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Before plywood, sheeting board was used.  A lot of houses, Western Pa, have sheeting board, floors, roof, sub-siding.  Available from any lumber mill, at the time.  Today, some of the walnut, oak, chestnut, cherry used for common sheeting lumber, at the time, has become premium sought-after lumber.    Who would a thunk. 

Edit/Add: The old farm house, my home, when young was built from Chestnut, (worm-ee Chestnut), available from the Chestnut blight at the time.  Large trees, all die-ing at one time, the effort was to use as much of lumber as possible.  Current bark beetle infestation, has caused a loss of many pine/ever-green trees, nation-wide.

Last edited by Mike CT

That is really true. The house I live in is a 1950s development house. The roof and cladding is hardwood tongue and groove. One roof was an expansion, that had plywood, and when the roof was redone they had to replace like 4 sheets worth of plywood. The roof that had the tongue and groove needed nothing.

That wood from old houses when it is recycled goes for a pretty penny.

RE; the last three posts, it is the difference between old growth timber and new growth timber. Buildings and houses built 100 or more years ago have wood milled from trees that were around from before we were a nation. the wood is very strong and stable. Wood harvested today is grown as a crop and harvestsed long before it has a chance to fully mature. This includeds plywood The better plywoods have many more plys (layers held together by a layer of adhesive) which helps hold the wood and helps with the stabilization of it. There are many engineered wood products in use in construction these days that rely heavily on adhesives to structurally stabilize the wood mother nature didn't have the chance to. As a carpenter I worked on houses from many different era. Houses that were 100 years old had exterior trim that was in great shape just as strong as it was 100 years ago (unless there was an issue and water infiltrated for extended periods of time from behind it without being discovered), where as wood especially pine needed to be replaced on homes that were just 5 years old. Another thought on trees grown as crops are the trees grown for paper. Everyone trys to tell you to save a tree and go paperless, if that would happen all those trees planted for paper would NOT grow into a mighty tree. Those trees would reach the height they were bread to reach and just die. It is a crop planted to be harvested to make paper for the books we read the bills we get even the traffic tickets we get.

Sorry for the rambling it's hard to stop once I get going.

Dan

@Dan Kenny posted:

RE; the last three posts, it is the difference between old growth timber and new growth timber. Buildings and houses built 100 or more years ago have wood milled from trees that were around from before we were a nation. the wood is very strong and stable. Wood harvested today is grown as a crop and harvestsed long before it has a chance to fully mature. This includeds plywood The better plywoods have many more plys (layers held together by a layer of adhesive) which helps hold the wood and helps with the stabilization of it. There are many engineered wood products in use in construction these days that rely heavily on adhesives to structurally stabilize the wood mother nature didn't have the chance to. As a carpenter I worked on houses from many different era. Houses that were 100 years old had exterior trim that was in great shape just as strong as it was 100 years ago (unless there was an issue and water infiltrated for extended periods of time from behind it without being discovered), where as wood especially pine needed to be replaced on homes that were just 5 years old. Another thought on trees grown as crops are the trees grown for paper. Everyone trys to tell you to save a tree and go paperless, if that would happen all those trees planted for paper would NOT grow into a mighty tree. Those trees would reach the height they were bread to reach and just die. It is a crop planted to be harvested to make paper for the books we read the bills we get even the traffic tickets we get.

Sorry for the rambling it's hard to stop once I get going.

Dan

That is very true with the lumber industry, that much of what is used is specifically grown (to be replaced). Much of the old growth forest was cut down and what is left is (wisely) now regulated or outright not allowed to be cut. In colonial days they used to create the masts for the tall sailing ships from an old growth tree (it was one of the big reasons the English, with its navy, absolutely wanted the colonies and Canada). And when something becomes relatively scarce, like hardwoods, they become expensive. My house used tongue and groove (and this was a typical post war development) because it was readily available, prob a lot more than plywood was back then. Lot of the older houses, more than 100 years old, were likely made from local wood from a local mill or in some cases could have been cut down and milled on the property.

Plywood and particle board are commonly used because being manufactured, they can use whatever they have to make them. Sustainable lumber means in many ways the strength and characteristics are variable, much more so than old growth, so they had to figure out ways to work with it. Hardwoods have another big flaw, they have pine trees that grow pretty rapidly (like the stuff they use in the paper industry), can reach a pretty good size in a relatively short time (like 10 years), hardwoods grow pretty slowly and as far as I know, they haven't been able to create hybrids that grow fast with hardwoods.

bigkid said:

Hardwoods have another big flaw, they have pine trees that grow pretty rapidly (like the stuff they use in the paper industry), can reach a pretty good size in a relatively short time (like 10 years), hardwoods grow pretty slowly and as far as I know, they haven't been able to create hybrids that grow fast with hardwoods.

When you buy a bunk (500) of 2X4 SPF #2 studs for framing you can look at the ends and they will all have the heart of the tree (center ring) in them. So they can't be letting them get to a very large size. There are are great number of homes being built even with the cost of lumber these days. In my adult life I have seen the area from 30 to 50 miles west of Chicago go from open land fields, woods, farmland turn to roof tops for as far as you can see. I wonder how many of those rooftops have model train owners within and someone trying to figure out what to build that layout with.

@452 Card posted:

I started a similar fire on another thread referring to this discussion. After analyzing all the opinions, I'm going with 1/2" Baltic Birch under Homasote. Please- no cautions or lectures otherwise; that is the way it will be. There is a local plywood supplier here that has what I need for the usual crazy price, and it is what it is, period, dot. Thanks again, GRJ!

Nice choice "452'...doesn't get much better than Baltic birch!  I'm planning ahead to start my layout expansion late fall.  My go to product for the table top is 1/2" Underlayment "C" Fir...very stable, touch sanded face, and "C" core.  I'm comfortable with 24 OC.  I priced it at the local lumber yard yesterday at $84 a 4 x 8 sheet...outrageous to say the least.

I'll wait it out until commodity lumber and plywood prices come down (substantially).  It's amazing what effect increases in interest rates can have on commodity prices...so stay tuned

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