Hi all,
I am getting supplies together to expand my layout footprint, once the final touches are completed in the layout room.
Now the fun part - My local lumber stores, be they local "Mom & Pop" style or big-box "lowest & home" style, can not seem to keep in stock, at any price point, 1/2" plywood in 4x8 sheets.
Has anyone successfully used 1/4"plywood in HO scale?
I won't be walking across the layout, and HO trains aren't exactly heavy, but between trains, scenery, etc... it is not light weight either.
I'm trying to figure out if the 1/4' plus support would be better than a 2" foam with support substructure. (The local "home" big-box has all kinds of 1/4" plywood, plus a good supply of straight boards for support structure, but the 2" foam is higher priced currently.)
The original layout is 1" foam scenery base on 1/2" plywood with support structure, save for a 4x4 area of only 2" foam with support structure. (Under layout shelving unit on one end plus shelf brackets along other end.)
Could I get away with 1/4" plywood? Then I could use the 1" foam scenery base like the rest of the layout has already, and still be about the same cost as the 2" foam with a support structure.
Thanks!
Ricky W.
HO scale Proto-freelancer.
My Railroad rules:
1: It's my railroad, my rules.
2: It's for having fun and enjoyment.
3: Any objections, consult above rules.
Hello All,
I use 1/4-inch plywood over a framework of 1" x 4"s, on 24-inch centered grid-work, for my HO pike.
On top of that is a base of 1-inch foam.
This sits on top of the bed in the computer/railroad/spare room.
It is both lightweight; versus 5/8-inch MDFB, and structurally sound with the right grid work.
The advantage of 1/4-inch ply is it's light and easy to drill through for track feeders and switch machine linkage.
Unfortunately, 1/4-inch ply doesn't have the "bite" to hold under layout devices (ULDs) with just screws; switch machines, circuit boards, boosters, etc.
As with everything there are trade-offs.
If I were able to expand my pike I would still use 1/4-inch ply, in the way I have described, but use 2-inch foam and add reinforcement plates to accommodate ULDs.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
I used 1/4" plywood as a backdrop on a prior layout; I would think it would work on the layout but might need more bracing support underneath than 1/2".
Did you check the other way, to see if they had 3/4" plywood sheets in stock? I know a lot of folks prefer that to 1/2" plywood.
You could also use smaller sheets. I've used 1/2" 2' x 8' and 2' x 4' sheets. Works fine, easier to fit in the car than 4' x 8' sheets too!
ricktrains4824Could I get away with 1/4" plywood? Then I could use the 1" foam scenery base like the rest of the layout has already, and still be about the same cost as the 2" foam with a support structure.
I used 1/4" plywood under 2" of pink foam, but the only reason for the plywood was to make it easy to attach things like Tortoises to the underside of the layout. I used 1x4s on 16" centers for the frame. The structure is very solid.
To me, 1" pink foam seems to be way more flexible than the 2" stuff, but adding 1/4" of plywood would certainly stiffen it up. My suggestion would be to make a test panel to see if you think the 1" foam/1/4" plywood combo is stiff enough. If you make the test panel the same size as one section of your layout you will be able to use it in the layout if it meets your expectations. If it isn't stiff enough, you could try adding another 1/4" layer of plywood on top. If the layers of foam and plywood are properly glued together that should make a very solid surface.
One of the challenges to gluing the plywood to the foam is getting enough weight on top of the assembly to push the layers tight together. I didn't get that quite right so some of the edges of the foam sheets were higher than others. It wasn't a big deal to sand the foam down. I should have used a notched trowel to spread the adhesive caulking.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Dave & JJ - Thanks. The whole reason for the plywood was indeed under-layout items like tortii, wiring runs, etc... I will indeed have to think about tring it out.
Stix - They did have 3/4, but at $82 a sheet..... Way too high still! At least the 1/4 cabinet grade was down below $30 a sheet now.
hon30critterI used 1/4" plywood under 2" of pink foam, but the only reason for the plywood was to make it easy to attach things like Tortoises to the underside of the layout. I used 1x4s on 16" centers for the frame. The structure is very solid.
Another advantage of using 2-inch foam is the ability to carve features below grade.
I'm limited to what features I can model with the 1-inch foam I used. Using 2-inch foam would have allow me more modeling options.
hon30critterOne of the challenges to gluing the plywood to the foam is getting enough weight on top of the assembly to push the layers tight together.
I didn't glue the foam to the plywood. Instead, I used "Finishing Washers" with "Dry Wall Screws" to attach the foam to the 1/4-inch ply.
Each screw set was placed approximately 12-inches apart along the perimeter and down the centerline.
An advantage of "floating" the foam sheet(s) over the sub-base; whatever material or thickness of choice is, the expansion/contraction of the two differing materials does not transfer to the other.
The plywood can expand and contract at a different rate than the foam with minimal damage to each.
Hint: Don't drive the screws too far into the foam. The tops of the washers should be just below the surface of the foam. Any deeper and you might crack the foam.
Think driving pylons to stabilize the foam to the plywood base rather than "mating" the entirety of the two surfaces.
I used 1/4" plywood for the top deck of my modules. Support is spaced at about 24"-30". I also attached a spline underneath where the track runs, to eliminate the possibility of sag. The edges (fascia) are 6" tall and are 1/2" ply. REMEMBER, these have to be able to be picked up, moved and transported. They don't have the luxury of just sitting there.
No foam, except for some scenery atop the ply. To allow for fluctuations in contour, I set the ply at various heights, with some of the ply 2" lower than the zero point.
I've had these for almost 10 years, and there have been no problems.
I would expect you would have to use "proper technique".
I expect building materials, including 1/2 ply, to become more available.
Ed
I think the 1/4 inch with a 1 inch foam topper would be fine, but I would use a 16 on center support structure. You could laminate the foam to the plywood using adhesive to provide the combo its own rigidity as well.
- Douglas
So there might be a question whether to glue the foam to the plywood to make the assembly stronger. (doughless)
Or to keep the connection loose, to allow for differential expansion. (jjdamnit)
7j43kSo there might be a question whether to glue the foam to the plywood to make the assembly stronger. (doughless) Or to keep the connection loose, to allow for differential expansion. (jjdamnit)
Hi Ed,
I guess part of the issue is whether or not the glue is capable of holding the plywood and foam together over time. The OP doesn't mention where his layout is located. If he is in a basement and uses a decent adhesive I can't imagine things coming apart.
I screwed and glued my 1/4" plywood to the 1x4 subframe hoping that that would make the plywood more stable. My layout is in an unheated but fully insulated garage so I know there will be expansion and contraction. I don't plan on using a space heater except when I'm in the garage in really cold weather (which will make the expansion and contraction worse I imagine). Time will tell if my plan doesn't work!
hon30critter I guess part of the issue is whether or not the glue is capable of holding the plywood and foam together over time. The OP doesn't mention where his layout is located. If he is in a basement and uses a decent adhesive I can't imagine things coming apart.
I guess the consequences of the glue not holding over time is that OP will then have a floating foam base that some suggest in the first place.
16 inches on center would seem appropriate.
Or glue and screw three pieces together to make 3/4 inch ply.
The hobby costs money. There are only a few options one could have to save $50 in lumber costs.
Why not just use 1/2" OSB? It's entirely adequate for this application. Mount it smooth side down and paint that side white for better visibility under the layout. Screw foam to it from the top using wood screws and washers (or NBWs). Counterbore those holes or just put enough squeeze on the screws so the washer and screw heads recess themselves. Doesn't take many screws to hold the foam down and flat and it ain't going anywhere. You can take it apart if you want to.
George
Cured foam dose not expand and contract in any measurable way, plywood dose.
rrebell Cured foam dose not expand and contract in any measurable way,...
Cured foam dose not expand and contract in any measurable way,...
Implication being that if it expands or contracts, you didn't wait long enough.
Since any expansion or contraction with foam is likely to be the same on any axis (unlike plywood), then I would recommend storing the stuff for awhile. How long? Well, you very carefully measure the length. When the length stops changing over time, it must be cured enough to use.
There seems to be two major brands of the foam we use: "pink" and "blue". It would surely be nice if someone could obtain a fresh piece of each, and chart the shrinkage over time. That SHOULD give a hint to people how long to wait.
We're talking here, by the way, of non-reversible changes. As in "shrinkage".
I figure there's also reversible changes: the foam is a closed cell foam. There is gas inside each cell. As it warms up, the pressure inside each cell rises. This stretches the cell walls, and the cell expands. ALL the cells expand. It also goes in the other direction.
This likely explains the system of cracks that developed in my scenery surface (sheetrock mud) done over foam. In fact, I noticed the size of the cracks change depending on ambient temperature. If I had done this in a shallow bowl shape, it might have made a great mud-flat.
The above is likely measurable. Or was.
S&SS of NC, a modular group, builds their modules mostly of 1/4" ply. I believe. If you are interested in using the stuff, you can learn a lot from them.
For example, they use it not only for the top, but for the internal "cross bracing" underneath the top.
My big anxiety would be glueing an edge to a sheet (bracing underneath top). They clearly have pulled THAT off, however.
Quarter inch plywood is plenty strong for this use. Frame all four sides and mid supports 24" and you'll be fine. I built shelving 30' long floor to ceiling for my basement 35 years ago with this design. It is framed with 3/4 x 2 1/2 inch furring strips. It has upported bins full of books, lps, my bowling and ski equip just fine. It can certainly support my weight of 200#. Perimeter framing spans 48" between vert supports and is still as straight as when installed.
I would probably top it with 2" foam to give me more options for carving out ditches, rivers and such. A close thread wood screw gives plenty of grip for mounting stuff underneath layout.
I use 3/8 on 1x4's. Cross piece spacing varies as I'll be using Walthers under table switch machines but not afraid to add extra cross bracing.
I have been sourcing OSB instead of plywood, since they want the price of a Kidney for good plywood.
Our club used 1/4 inch stuff and it worked well enough even though we used more support beams.
Most of my layout is 1/2" plywood on 2' centers. I experimented with 2" foam on the first town I built but undermount switch machines were problematic so I did the rest of my towns with plywood. For the short stretches between towns, I used whatever scraps I could find for the subroadbed. Mostly 3/4" tongue-and-groove paneling leftover from my home construction.