1/4" plywood for N scale?

[Metro Red Line]

I'm building my first N scale layout and wil use a combination of traditional plywood construction and foam. I'm planning to put a 1/4" plywood board in between the benchwork and the foam, and cookie-cut the plywood for subroadbed in the inclines. Is that thick enough to support N scale trains and track? My crossbraces are 16" apart. Will it sag or will it be sturdy enough?

[Anonymous]

You would be better off with the next thickness of plywood as 1/4" will warp faster and will not be any where near as sturdy as 3/8" or 1/2" In fact, when you measure 1/2" it will be just short of being 1/2" thick.
I used 3/8" for my current N-Scale RR and it has worked very well.
If I were to build a much larger RR, I would definitely use 1/2" framed by 1"x4"s.
Good luck,
gtirr

[pcarrell]

I had a very similar setup on my last layout, though I used 12 inch centers and my foam was only a 1/4 inch.  I've had no sag problems in three years.  I bonded the foam to the 1/4 inch luan board with latex caulk and it worked well.  I boxed the frame with 1x4's and all the cross braces are 1x3's.  With 16 inch centers you should be OK if you use thicker foam (say 1/2 inch to 3/4) and bond it to the plywood.  They gain strength off of each other that way.  I think most people way over engineer their layouts.  I wanted light weight and ease of working materials.  (It's light enough that I carried a 9x4 section out of the old house and loaded it in the van by myself)

I just happen to have moved recently and I have part of my old layout stashed in the garage.  I'll run out there and get a pic to show you what I'm talking about and give you an idea of how it's held up.  Hang on........

OK, I'm back.

Right now this is leaning up against the inside wall of my garage, so pardon the pic quality please.  This is a 9x4 section that I salvaged from the last layout.  Here it is.....(These pics can enlarge quite a bit, so beware if you have a slower connection.  They load small at first and then you can blow them up.)

http://i83.photobucket.com/albums/j319/pcarrell/Model%20Trains/Salvage/Picture026.jpg

Not this part shows a track that is crossing over other tracks below it.  It's supported every 12 inches.  Notice how thin it is (1/2 inch thick, plus the track) and yet theres no warpage in three years of Indiana heat, cold, and humidity. (Though you'll notice towards the bottom of the pic I dinged the foam when we moved it.)

http://i83.photobucket.com/albums/j319/pcarrell/Model%20Trains/Salvage/Picture030.jpg

Hope this helps!

[CascadeBob]

My last layout (N scale), used 1/2" 5 ply plywood with Homasote glued on top with yellow Elmer's carpenter's glue.  This was supported on 12" to 16" centers on "L" girder benchwork.  I never had any problem with warping or sagging.  I'm about to start work on a new N scale layout in which I'm considering using 3/8" or 1/2" BC grade pine plywood with 2"-thick extruded foam glued to it with laxtex caulk to allow for easier terrain carving along the tracks.  This may be overkill, but this will probably be my last layout so I'm going to pay the extra for the thicker plywood and do it solid the first time.

If you do decide to use the 1/4" plywood on your layout, be sure to take a tape measure with you to the lumber yard.  As pointed out above, the thicknesses listed at the lumber yard are only the nominal thickness, not the actual which is thinner.  For example, the 1/4" luan plywood sold in our Home Depot is only 5 mm thick.  Sometimes the product is incorrectly labeled on the rack where it's displayed.  I recently bought a 4' x 8' sheet of what I thought was 3/16"-thick peg board at Lowe's.  When I got it home, and compared it to a 3/16" thick piece I'd bought at Home Depot it turned out to be 1/8" thick.  Now I always take a tape measure with me when I buy plywood or lumber.

Hope this helps,

Bob

[selector]

If your foam is at least 1" thick, and you support both the plywood and foam with 16" centres, you will be fine.  In fact, you would be fine with 24" centres.  However, if just the 1/4" plywood, I would reduce it to the 16"

We overdo things in the hobby because so much of our personality and emotion brings to bear on what we create.

[jeffrey-wimberly]

Personally, I wouldn't use the 1/4" plywood. I did that once and had issues with overall strength in the layout design. I ended scrapping it and using 1/2"

[TomDiehl]

I'm building my first N scale layout and wil use a combination of traditional plywood construction and foam. I'm planning to put a 1/4" plywood board in between the benchwork and the foam, and cookie-cut the plywood for subroadbed in the inclines. Is that thick enough to support N scale trains and track? My crossbraces are 16" apart. Will it sag or will it be sturdy enough?

The weight of N scale trains and track isn't going to be much of a factor as to how much sag will occur in your benchwork. Bigger factors will be the thickness and width of your roadbed, the spacing of the supports (your crossbraces are 16 inches apart, and support will be farther apart if you go across the grid on a diagonal), the moisture and temperature fluctuations in your layout room, and whether your sandwich of foam and plywood is going to be glued together for a sort of hybred plywood/foam. By itself, 1/4 inch plywood, spanning 16 inch spaced supports will sag or warp, regardless of the scale. You need closer spaced supports (only a "might work" in this case), or thicker plywood (recommended).

[R. T. POTEET]

I, too, am an N-Scaler but I am a plywood and homasote man - I may do my next layout in foam if I can find it when I am looking for it which appears to be next to impossible - but the thinnest plywood I have ever used for roadbed is 3/8".  That was on my first HO layout after I retired from the service in 1978.  Admittedly, I did it as an economic measure but then I got cold feet and built my benchwork on a 14" grid so, in the long run, I probably didn't really save anything.  All of my subsequent layouts have been built using 1/2" ply with 18" grid on my benchwork.  I did not experience any kind of problem with my 3/8" ply but I'm not sure what the ramifications would be with that thickness of sub-roadbed and a 16" grid.  I would not, however, try it and would go to at least a 3/8" ply for my sub-roadbed.  Where I do use 1/4" is for my structures platforms.

Remember this in regards to the weight of N-Scale equipment and roadbed: in the words of the late Senator Everett Dirksen (R-Ill) - "A billion dollars here and a billion dollars there and pretty soon you are talking about real money!" - okay, so it was only a million dollars but you get the point!!! 

[tomikawaTT]

On my HOj (twice-N scale on HO track) layout, I'm using a lot of quarter-inch plywood for cookie-cut roadbed, with no foam overlay.  However, these three caveats apply:

1. In most places there are two layers of plywood glued together, so the thickness is actually 1/2 inch.  The two layers are being arranged so that warpage cancels out.
2. Where only a single layer of plywood is used, warpage is beaten into submission with a liberal application of steel angle iron and lots of risers from my L-girder frame.
3. In places where clearances dictate only one thickness of ply with no reinforcement, I keep the span as short as possible and increase the roadbed width to provide solid anchorage.

I don't expect to walk around on the roadbed, and HOj trains don't weigh much.  As long as the grades and curves remain uniform, I'm a happy camper.

Chuck (modeling Central Japan in September, 1964)

[whywaites]

I built a Swiss n scale layout from 1/4 inch ply I was given 24 4'x8' sheets of the suff, it was lightweight and stable but I laminated with wood glue so in effect I had 1/2" ply (well just under as it was metric sheets which were 5.5mm)

Shaun

[nucat78]

I'm building my first N scale layout and wil use a combination of traditional plywood construction and foam. I'm planning to put a 1/4" plywood board in between the benchwork and the foam, and cookie-cut the plywood for subroadbed in the inclines. Is that thick enough to support N scale trains and track? My crossbraces are 16" apart. Will it sag or will it be sturdy enough?

Ok, I'll be the heretic here.  I use 2-inch foam on shelf brackets screwed into my wall studs for a shelf layout and I don't use plywood at all.  Laminate a 1-inch thick foam sheet to the bottom if you want a lowest elevation datum.  Cheap, easy, quick and light if you ever have to move the beast.

But you should shield the edges of the foam with something as it will dent and ding.

 

 

[Metro Red Line]

Ok, I'll be the heretic here.  I use 2-inch foam on shelf brackets screwed into my wall studs for a shelf layout and I don't use plywood at all.  Laminate a 1-inch thick foam sheet to the bottom if you want a lowest elevation datum.  Cheap, easy, quick and light if you ever have to move the beast.

But you should shield the edges of the foam with something as it will dent and ding.

 

I've decided to go with foam (1" blue; the 2" is way expensive) over 3/8" thick plywood panels.
Should I glue or screw the foam to the plywood?

[nucat78]

Ok, I'll be the heretic here.  I use 2-inch foam on shelf brackets screwed into my wall studs for a shelf layout and I don't use plywood at all.  Laminate a 1-inch thick foam sheet to the bottom if you want a lowest elevation datum.  Cheap, easy, quick and light if you ever have to move the beast.

But you should shield the edges of the foam with something as it will dent and ding.

 

I've decided to go with foam (1" blue; the 2" is way expensive) over 3/8" thick plywood panels.
Should I glue or screw the foam to the plywood?

Glue, but make sure it's compatible with the foam like Liquid Nails for Projects or a latex based caulk or the foam will dissolve.  I wouldn't trust screws to hold.

 

[Metro Red Line]

Glue, but make sure it's compatible with the foam like Liquid Nails for Projects or a latex based caulk or the foam will dissolve.  I wouldn't trust screws to hold.

 

Thanks. My reason for wanting to glue is in case I want to dismantle the layout, I can recycle the benchwork and the plywood top. I guess I will draw a grid pattern of the adhesive (latex caulk or carpenter's glue) to make things more organized.