Regular birch plywood does the job as well, keep the costs down by leaving the oak out
Btw, I build my modules using 1/2" plywood at the ends and 3/8 plywood at the sides - strong enough. We model railroaders tend to overdo it a little when it comes to selecting the materials for our benchwork.
Allegheny2-6-6-6 Ken uses 3.4 plywood cantilevered directly from the buildings studs and his bench work is so strong and stable you can stand on it. Good luck and enjoy your new railroad.
Ken uses 3.4 plywood cantilevered directly from the buildings studs and his bench work is so strong and stable you can stand on it.
Good luck and enjoy your new railroad.
Excellent news. That is exactly how I have planned my layout.......3/4 inch and every piece will be attached on one side directly to a wall stud....even the pieces that are entire sheets.
I was looking over the oak and birch 3/4 in plywood just the other day. At $75 per sheet at Home Depot is is some of the most expensive building material onsite, but I am going to go for it. I need 7 full sheets but as the British say, "Start as you mean to go on"...........and I mean to have this layout outlive me.
Humidity in the 40% - 70% range may not have much effect on most forest products - but here in the dessicated desert humidity that requires two digits to describe is considered unusually high. Today it's 11%, somewhat above normal. Add another 1 and you have the present temperature (44 degrees Celsius.) Believe me, if you bake plywood in a low humidity oven, it WILL assume wierd and (not so) wonderful shapes. And, if your layout coexists with a gas-fired water heater and local code requires vents open to the outside, climate control is NOT an option.
My own layout puts thin (<3/8<) cookie-cut plywood over a steel structure, with a thin (9mm) layer of foam laminated to the plywood with latex caulk. If the plywood attempts to deform I beat it into submission with steel angle iron - screwed to the underside. Some of it has been in place, and in operation, for five years now. And, yes, it IS quiet.
I am not a big fan of gluing everything into a monolithic structure that has to be disassembled with a recip saw. Model railroads have a tendency to get physically modified to meet new situations ranging from changing interests to expansion (or contraction) of available space. I prefer being able to remove screws and salvage structural components for re-use - or simply move them a few inches if necessary to clear the pit of the new turntable.
Chuck (Modeling Central Japan in September, 1964)
I am getting the feeling that I am going to be alright with simply plywood for benchwork. I imagine that 3/4" ripped into 3 inch wide pieces might be better than 2x2s for table supports with regard to warping too....or are KD 2x2s preferred?
My 3/4" birch plywood is ripped into 4" wide lengths for bench work and I use 2x4 for legs. There is no such thing as too strong or over built bench work. For the penny's you'll save by making 2x2 legs and lighter bench work etc. It will cost you greatly in the end. Check out Ken McCorry's Conrail layout from the Allen Keller video series I believe he has a website but you can read about his magnificent 500sq. ft layout at
http://www.trainorders.com/discussion/read.php?3,1195272
Now, is marine grade plywood any superior in terms of shrinkage? I wonder if it would be worth it to spend the extra for the humidity resistant glue in the marine product?
Marine grade plywood is outrageously expensive and would be a waste of money to build a model railroad. I was told by a cabinet maker and also by a board member that you should use cabinet grade plywood either birch or oak. Cabinet grade ply has more layers of lamination therefore making it stronger and "more stable" as well as it takes screws much better then conventional plywood. Remember you will be screwing and gluing right into the edges of the cut pieces so this is an import thing to not over look. I can attest that if my bench work was not clamped and glued just the screws themselves would not hold very well. Depending on what type of bench work your planning on using L-girder or open grid or cookie cutter and plywood that will be directly on the top surface of the bench work I also recommend screwing and gluing the plywood down just like they do with sub-flooring in a house. This too will add to the strength and stability of your bench work.
Cisco KidNow, is marine grade plywood any superior in terms of shrinkage? I wonder if it would be worth it to spend the extra for the humidity resistant glue in the marine product?
Back in the bad old days, not all plywood glues were reasonably waterproof. Regular plywood would delaminate (the glue would let go) when immersed in water. Exterior grade plywood used glue similar to that of marine plywood, that would not let go in water immersion. Nowadays, virtually all plywood uses waterproof glue.
Marine plywood has to consistently meet all its specs, as it is usually used as a visible part of an engineered structure. Voids (gaps in the inner plys), knots, and the actual wood used in the plywood are tightly controlled. In almost all cases, marine plywood has to have at least one A surface and one B surface (filled knot holes are allowed in a B surface).
Contrast the quality of marine plywood with CDX, which is used in construction as a support surface where it will not be seen. Neither is wrong, both are engineered for their uses.
The more layers (plies), the less likely the plywood is to warp or change dimensions from varying moisture contents, as the plies "fight" each other. This is very similar to the way using regular lumber in an L or T girder uses the different cross grain alignments to prevent and reduce warping. Voids and knots in plywood also affect susceptibility to change from varying moisture content, as they create areas of non-uniform moisture content.
So, yes marine plywood will have a little more dimensional stability and much improved resistance to warping than the same thickness in CDX.
The worst cases I know of is plywood in variable humidity areas like the Gulf Coast. There, I have been quoted expansion figures of 1/4" for an 8ft sheet of plywood from when dry. I personally have seen 1/8" shrinkage of an 8ft sheet CDX plywood from its wet or green state at the lumberyard while in storage at my house. But I can't afford to store marine grade plywood to check! Humidity at my house runs from 40% in the winter with the humidifier on (and almost nothing outside) to 10-20% during the summer (no air conditioning at 7800ft). That is a big change from the environment of the saw mills and plywood and veneer plants, so letting wood "season" gets the changes over with.
The real issue for me is warping due to uneven drying. I have to make sure my storage and use prevents warping, especially when using grades like CDX.
Unless you live in a highly variable humidity environment, letting plywood "season" for a few weeks before using will reduce any dimensional change to negligible.
just my experiences
Fred W
I use 1x4s with just white foam on top, been in the garage for a few years now, nothing bad has happened but then I don't solder the joints of the rails.
Cisco KidSir Madog Plywood in general (in the right dimensions, of course) is much more stable than regular lumber. ....... So far, I never found it necessary to paint my plywood benchwork, although humidity in my train room varies from 30 - 40% (in winter, when the heater is going) to 80% in wet summers. Thanks for all the responses, gentlemen. I am getting the feeling that I am going to be alright with simply plywood for benchwork. I imagine that 3/4" ripped into 3 inch wide pieces might be better than 2x2s for table supports with regard to warping too....or are KD 2x2s preferred? Now, is marine grade plywood any superior in terms of shrinkage? I wonder if it would be worth it to spend the extra for the humidity resistant glue in the marine product?
Sir Madog Plywood in general (in the right dimensions, of course) is much more stable than regular lumber. ....... So far, I never found it necessary to paint my plywood benchwork, although humidity in my train room varies from 30 - 40% (in winter, when the heater is going) to 80% in wet summers.
Plywood in general (in the right dimensions, of course) is much more stable than regular lumber. .......
So far, I never found it necessary to paint my plywood benchwork, although humidity in my train room varies from 30 - 40% (in winter, when the heater is going) to 80% in wet summers.
Thanks for all the responses, gentlemen.
Ulrich
My 5' x'10 foot piece of plywood I believe came from this company. http://www.smithplywoods.com/
There was only one mill in North America that could produced that size so I was told. It was just given to me years ago by someone who had no use for it. So I gladly accepted it.
I don't know if they still make that size as I believe it was a special order for one company that used it for a special industrial application many years ago. But it is indeed 5' x 10' It weighs a ton and is a beautiful piece of wood to boot.
Edit; I just noticed on there website they still produce it. So it is the right dimensions.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
Plywood in general (in the right dimensions, of course) is much more stable than regular lumber. If your layout is in a humidity controlled environment, you won´t have much of an issue with shrinkage/expansion and warping. Sealing the plywood adds a little more stability - but: make sure to do this at a "dry" time, not to trap any moisture inside the plywood!
Are you building a boat or a model railroad? As long as the R/H (relative humidity) as low as possible and your not working in a damp dank basement warping plywood should never be an issue.The glues and the pressures involved in manufacturing of plywood is incredible.
You should always screw and glue your plywood to your bench work if you want to assure maximum strength and stability.
Thats why the building trade is now screwing and gluing sheathing and dray wall as opposed to just nailing it like they have done for so long. It makes for a much tighter stronger house and will do the same for your bench work. Rather then put a band-aid on it by treating the bench work with what ever try and cure the cause of your moisture problem if in fact you do have one.
Cisco. Working through cement board is near impossible. Think about feeders, switch machines phone poles and such. Although, it is quiet. I have a 70" stretch on my layout. Feeders on either end so I'm okay there.
I have a 5 x 10 piece of plywood in my house that use to hold my last layout. It is now used for other things but it is still like brand new. I don't think you need to paint if it's kept inside the house.
How big is you're layout going to be? I kind of look at layout building like bridge building. In both cases method and materials used to construct them depends on surroundings, environment, how big and whats the budget. One can lay a lot of miles of spline for the cost of a couple of sheets of decent plywood.
Cisco, make sure you are using the right kind of foam. The Pink or Blue builders foam is used for insulation and should be very stable. It should be on top of the plywood and not under it. painting the plywood will seal it and make it less susceptible to moisture changes. The recommendations earlier of using rail gaps will take care of most issues.
Springfield PA
I agree with the folks who say painting it probably wouldn't make any difference one way or another - just start with a reasonably flat piece of plywood and brace it well - I use 3/8" and put styrofoam building insulation on top of it.
Won't do any good sealing the plywood. as soon as you drill holes for feeders and switch machines, it isn't sealed any more.
73
Bruce in the Peg
IRONROOSTER Leave expansion gaps in your track. I didn't 2 layouts ago and track at one joint twisted out of the tie strip after about 15 years.EnjoyPaul
Leave expansion gaps in your track. I didn't 2 layouts ago and track at one joint twisted out of the tie strip after about 15 years.
Enjoy
Paul
I had the same problem and I left 1/32" gaps in the rail and did NOT solder all of them. I maintain good electrical contact by running a buss and soldering track feeders to each section of track. Rail joiners should only be used to maintain rail alignment, not for electrical contact. Although I'm sure you'll hear about all kinds of arguments against it. It's what works for me.
Marlon
See pictures of the Clinton-Golden Valley RR
As stix points out, so long as you select a reasonably flat piece of plywood and attach it to some kind of framing, it will be fine. Sealing it will make no noticeable difference and seems like a waste of time and materials. Foam is equally stable. Beware of things like chip board, Homasote, etc.
John Timm
Paint the plywood with Thompson's water seal then go over it with a good coat of enamel paint.
Dr. Frankendiesel aka Scott Running BearSpace Mouse for president!15 year veteran fire fighterCollector of Apple //e'sRunning Bear EnterprisesHistory Channel Club life member.beatus homo qui invenit sapientiam
painting or sealing the plywood on both sides and the edges will keep what is inside from changing. think about it.
3/4 plywood is probably better than 1/2" but it is like wrestling with sheet steel.
also, if you can keep the humidity between around 35 and 60% i bet you won't have much trouble with dimensional stability. humidity seems to be a bigger factor that temperature.
i picked up a little cheapy humidifyer at wally-world to run in the winter time. it keeps my basement from drying out too badly and in the summer, i run a de-humidifyer and let the water run down the floor drain. a box fan from the dollar store keeps the air moving around.
grizlump
wjstix I'm not aware of anyone putting plywood over a foam base,
I'm not aware of anyone putting plywood over a foam base,
Yeah that looked funny when I wrote it, but I realized I got the idea from another member's post linked inside the recent post on this topic.........he listed results of his testing various configurations. I don't think I would ever bother with wood over foam.
What I am worried about is not sagging, but shrinkage or expansion and warping along the butting edges. I ended up with gaps between sections of my first layout built on MDF sections.
Well, painting will only affect the surface layers, not what's inside. FWIW I've never really had a problem with plywood changing over time - if it's flat when you buy it, and you brace it properly, it will stay flat. If you're concerned about stability or possible sagging, go up to 3/4" plywood which is quite a bit firmer than 1/2".
Cisco Kid In the irreconcilable plywood vs foamboard debate, I have come to believe that foam is likely to be too noisy without a layer plywood on top, which negates the temp/humidity stability of the foam I was looking to achieve.
In the irreconcilable plywood vs foamboard debate, I have come to believe that foam is likely to be too noisy without a layer plywood on top, which negates the temp/humidity stability of the foam I was looking to achieve.
I'm not aware of anyone putting plywood over a foam base, though some people have built a plywood base and use a layer or layers of blue or pink foam over the plywood. If you have a solid plywood base with wood bracing underneath, you can use Woodland Scenics risers to support the track and raise any buildings etc. up to track level. That might be easier than laying track on the foam or plywood directly, and then cutting away areas where you want scenery to go below track level.
Therefore, I am wondering if painting 1/2" plywood would appreciably increase its dimensional stability.
I do have the layout space under temp and humidity control now, but even so, the main floor humidity at this time of year is about 68% and will be about 40% or lower in winter......so 68% is my best score.
I do have the area controlled for heat.
I imagine the edge painting will have to be done after the plywood is ripped into layout shapes and installed, as merely painting the surface will be only partially a solution.
I have been thinking that plywood with a layer of the thin form of Durock II on top might be the ideal solution. That should be absolutely sound proof and absolutely stable I am thinking. In my case most of the Durock would be scored and snapped into 2' by 6' sections which are not that heavy.....about 6 pounds each.
Any thoughts?