With the new SIW being made as a 24" wide L shaped switching layout I am wondering what thickness of Plywood is needed to maintain dimensional stability and avoid any warping in a climate controlled environment such as our extra bedroom where the layout will be located?
Joe Staten Island West
Half inch of good grade should do okay if supported about every 14" or so below it. I personally like the heft and strength of GIS 5/8" plywood. I built my first layout with three sheets of it placed side-by-side supported by 2X4's. I had the 2X4 joists about 2' on centers, and never had a sag. It was overkill because on top of the plywood I placed 1.5" extruded foam insulation board.
Oh well...we all have to learn.
Joe,
Lots of variables to think about, but if you don't want to worry about it use 3/4". Personally I mostly use 1/2" (open grid benchwork with 12"-15" spacing) and have never had a warping issue, but I live in SoCal and have my layout in an extra bedroom.
The reason I choose 1/2" is mostly related to weight. I am 63 with a bad back and humping that 3/4" plywood Up and down stairs is more that I can handle!
Tim
I think that we model railroaders tend to overdo things when it comes to selecting the dimensions of the material we use for our benchwork! Come on, folks, the cold war is over and Khrushchev will not be dropping the A Bomb on our layout!
1/2" plywood is more than enough! My layout base is made of 6mm plywood, that´s less than 1/4", supported every 12" with joists made of 1/2" plywood. No sagging, no warping!
I use 1/2" plywood with grid framework , joists on 16" centers, no overhang. All 4 sides screwed to the grid plus about 12" in on interior joists. This works fine in my climate controlled basement.
If you go with cheap plywood, you do have to watch the joints as you can have a little warp at the edges so they don't mate up exactly. You may need to shim one side.
Cheap 1/2" plywood has 4 plies (sometimes 3, but don't get 3). Better grades have 5 and the best stuff has 9. The more plies, the flatter and more stable the plywood - but the more expensive.
Good luck
Paul
Ulrich
I think one of the issues for many of us is stability. In a perfectly controlled environment thinner plywood would work fine, but when you are facing temperature and humidity swings that many of us do because of where the layouts are located, you are much safer to go with more plys rather than fewer. The added weight carrying capacity is not the issue. In the OP's case, I agree that he doesn't need heavy duty plywood as long as the benchwork is good.
I do think that if you are going to use 5/8" or 3/4" plywood then having the joists spaced at 16" or less is a bit of overkill. After all, you are not building a dance floor. Obviously the framework has to be designed to carry the weight over whatever total spans are involved without sagging. That's where 'L' girder style construction has its advantages.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
One side smooth 1/2'' ply...1x3/2x2..frame,16'' center's..lay a bead of yellow carpenter's glue on frame, attach ply with drywall screw's or in My case air-brad nailer. Very strong, will not shrink/expand, will break first...not probable. Going on 36yrs. for mine and I live in a four season area, 15yrs. before temp control, layout in attic.
I agree with Ulrich..people have a tendancy to over kill when building a support for a layout. Mine was 12 1/2x 40 x 12 1/2 in sections bolted together. I made it smaller by taking sections out, intact and gave to Grandkids, who have a layout in basement. Mine is now 8 1/2 x 32 x 6 1/2. I also use 1/2'' Homasote over 1/2 ply...You can't beat it for holding spikes, nails, screw's..not the junk they sell in big box stores...the real exterior Homasote, that is already treated for weather conditions. I hear this alot on the forums about it swelling....well they forgot to tell that to the stuff I've been using. Your choice....Your build.
Take Care!
Frank
Looks like the consensus is 1/2-inch plywood. I agree. Some go with 3/4-inch, which is fine but it's more expensive and a lot more unwieldy and heavy to work with. If reasonable supports are used, as mentioned above, you'll be fine.
Like Frank, I like Homasote over plywood - makes a good sandwich for installing a rail yard on. I do painted both sides to help it resist moisture and it also gives a nice base color that you can apply scenic material or ballast onto.
Rio Grande. The Action Road - Focus 1977-1983
I cut my framework from 1/2" plywood sanded 2 sides from HD. I used 2" formula 250 for my top, liquid nailed on `16" centers. No warp issues and very quiet when cork is the roadbed.
TomO
hon30critter Ulrich I think one of the issues for many of us is stability. In a perfectly controlled environment thinner plywood would work fine, but when you are facing temperature and humidity swings that many of us do because of where the layouts are located, you are much safer to go with more plys rather than fewer. The added weight carrying capacity is not the issue. In the OP's case, I agree that he doesn't need heavy duty plywood as long as the benchwork is good. I do think that if you are going to use 5/8" or 3/4" plywood then having the joists spaced at 16" or less is a bit of overkill. After all, you are not building a dance floor. Obviously the framework has to be designed to carry the weight over whatever total spans are involved without sagging. That's where 'L' girder style construction has its advantages. Dave
YOU MUST USE 16" Centers!!! You want to be able to get a drill between the supports for wire raceways, and even if you drill those in advance, you will always want more holes.
LION uses 16" centers, but him uses no plywood. Him used 1/2" Celotex, very flat very stable very smooth, easier to cut than Homasote. LION used 10 sheets of this product on the layout of him. Only drawback, as far as I know, is that this stuff has not been made in the past 60 years. Well not since the advent of fire codes. They used to make walls and ceilings out of this stuff.
LION found his in the Abbey warehouse, it must have been saved from some buildings that we have torn down or renovated.
Oh well, there are many other things that I would rather use than plywood. You know about foam, and LION has used that, but one of the nicest materials that I have used is 2" thick fiberglass roofing insulation. It is smooth, it is firm, it has a paper cover that will help hold nails, although gluing will eventually be required, but ballast will take car of that. LION got his at a worksite where contractors were replacing a roof on the local donut shop. I asked if I could salvage pieces from the dumpster, and they said it was ok. I used this material for both the risers and for the rail deck, and I was able to get away with 20" centers on the supports.
LION likes soft material for the rail deck, makes holes for wire and signals easy. Two inches is a bit thick for a Tortoise, but I can mount the tortoise on the far side of the rail deck, and mortise a ditch for the throw rod. More that one way to skin a Tortoise, ewe know.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
Lion,
I am using this:
mounted to my drill to drill holes into the supports spaced only 12" apart!
Sir Madog Lion, I am using this: mounted to my drill to drill holes into the supports spaced only 12" apart!
Hey, I never thought to use a proctoscope, Ulrich! That's brilliant!
You will never be sorry if you overbuild it. If you underbuild it and it sags or causes other problems well you probably wont like the repairs.
You have heard that there is an exception to every rule and here is is another.
My father built my layout in the late 1930's for my Lionel trains. It consisted of 4' X 4' sections made of 1" X 3" frames without any additional framing with YES 1/4" plywood. There were 3 sections that were bolted togther and laid on the floor. They were put down every Thanksgiving and and taken up mid Winter as they were in a used bedroom. They survived my abuse as well as my son's. When my son came of "age" we reserected the sections and put legs on them. When I got back into RRing in 2007 I put them back into service again but addeed two sheets of 3/4" foam on top
.
The sections have always been in a dry and steady environment. There are advatages to the thiner ply especially when dropping feeders etc. If your environment will permit go with less.
Bob
Don't Ever Give Up
post deleted
- Douglas
1930's 1/4" ply was easily as good as today's 1/2", which is probably hy that held up so well over all these years.
1/2" 9 or 12 ply hardwood ply is probably better than 3/4" AC 5 ply. There are a lot of factors, it's not just the thickness that counts, but how many plys and what they are made of, as well as the grade of the wood. I usually take a look at plywood options when in the store, still planning, not ready to buy yet but I like to see hat's available. I REALLY need to find an alternative, because neither of the big box brands around me have anything really worthwhile.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Thanks everyone. I have was in Home Depot this week and all I saw was 3 ply 1/2 inch sheets. I may have to check with a local lumberyard for multiple ply sheets.
However the gentleman who is actually building the bench work for me may know of a supplier. I am also having trouble sourcing Homosote but he may know where to get that as well.
Joe 323,
The local lumberyard will almost certainly be your best bet. I used 1/2", 5-ply, B-C plywood which has proven to be just fine. Supports are 12-16" o.c. It is topped with 1/2" Homasote for spiking (screwed, not glued) but was quite level and stable without it.
Dante