Thickness of benchwork plywood?

[Anonymous]

I've heard to use anthing from 3/8's all the way up to 3/4 inch plywood... I'd love to be able to use 3/8" due to it's low cost, and since I'll be laying at least a couple sheets of foam on top, would that be strong enough to support the weight of the layout? L-girder construction, joists are approximately 12-16 inch spacing depending on where they are on the layout. I do hear that 1/2 inch or thicker would be ideal, but this is a large layout that will require at least 7-10 sheets of plywood, and I'm trying to keep costs down as much as possible.

Thoughts?

[cacole]

With two sheets of foam on top, you should be able to get away with 3/8" plywood, but without the foam you would definitely need at least 1/2" thickness.

[Anonymous]

I agree with cacole. To add strength, glue the plywood to the L-girders in addition to your nails or screws.

[CP5415]

I'm using 1/2 plywood without foam & it's pleany strong.
3/8 will be strong enough for what you are planning

Gordon

[markpierce]

Never had a problem with half-inch plywood, but I don't live an area of hot humid weather.

[Anonymous]

I should probably mention that around here it's really hard to find the standard 2" foam sheets that most people use. I'll only be using probably two or three 1/2" sheets (which is what's primarily available) glued down to each other and the plywood tops of the benchwork. DIdn't know if that would affect your answers or not.

[orsonroy]

Most of my three level layout is 1/4" plywood and 2" foam. With a 2x2 box frame support on the lowest level, it's plenty strong enough for my 225 lb butt to walk around on!

[IRONROOSTER]

I use 3/8 with joists on 12" centers with no problem. After you fasten it to the benchwork you can test it for deflection, but I don't think you'll have any.
Enjoy
Paul

[TBat55]

I use 1/2" plywood (almost standard for house roofs; scrap pieces are easy to get).

Tortoise switch machines say "one inch" for the wire going up through the roadbed to the turnout points. 1/2" ply + 1/2" Homasote + cork leaves maybe 1/16" of wire to trim off. Of course you can always buy and install longer, thicker wire.

[jacon12]

I used 1/2 inch and the entire cast of Riverdance could dance on it. Well, that may be a slight exageration.
Jarrell

[Anonymous]

I used 3/8" but you have to make sure and glue and fasten it really well.
Next layout will be 3/4"

[grayfox1119]

I am using 3/4" plywood. I too have read comment after comment , and after having used plywood of every thickness for a variety of projects, and witness the warping and bending of thinner pywood, there was no doubt in my mind that I was going to use 3/4".
For small layouts, and widths of 24" or less, you can get away with thinner plywood, especially if you space supports beneith at sufficient intervals.

But considering the value of what is on top of those tables, doesn't it make sense to have the strongest surface that you can afford? I know for some of you folks, the cost of 3/4" plywood is too high at $25-$28 a sheet, but what do you pay for ONE engine?

[orsonroy]

QUOTE: Originally posted by grayfox1119

I am using 3/4" plywood. I too have read comment after comment , and after having used plywood of every thickness for a variety of projects, and witness the warping and bending of thinner pywood, there was no doubt in my mind that I was going to use 3/4".
For small layouts, and widths of 24" or less, you can get away with thinner plywood, especially if you space supports beneith at sufficient intervals.

But considering the value of what is on top of those tables, doesn't it make sense to have the strongest surface that you can afford? I know for some of you folks, the cost of 3/4" plywood is too high at $25-$28 a sheet, but what do you pay for ONE engine?

This is sort of like telling someone to use 4x4s for legs. Why bother?

I don't build layouts out of 1/4" Lauan and 2" foam because I'm a cheapskate or poor. I build that way because it's fast, an efficient use of my money, and plenty strong for shelf layouts (and my three level is basically nothing but a gigantic shelf). I could have built with 3/4" or even 1/2" ply, but it would have been a waste of my money, considering the added strength of the extra-thickness plywood isn't important on a non-load bearing shelf layout.

But if it makes you feel more secure, go ahead and use 1/2" or thicker ply. But just think of the extra goodies you could have on TOP of your foam if you didn't blow that money on wood!

[grayfox1119]

Notice I said...for smaller widths ( ie shelf layouts), thinner plywood is fine. I am taking about layouts on benches, and layouts 30" wide and wider. No one is going to need to climb on a shelf layout.

[chateauricher]

But is a plywood deck of any thickness really absolutely necessary if you are using 2" of extruded foam? Let's presume, of course, you have an adequate support frame underneath. Is the foam not rigid and strong enough to support the tracks and scenic elements without resorting to expensive plywood?

By not having a plywood deck ...

wiring would be simpler -- no holes to drill (in the wrong place), just poke a hole in the foam with a coathanger or awl;

undermounted switchmachines could be mounted closer to the surface by simply cutting a hole for it;

no worries about seasonal expansion/contraction.

[Big_Boy_4005]

QUOTE: Originally posted by chateauricher

But is a plywood deck of any thickness really absolutely necessary if you are using 2" of extruded foam? Let's presume, of course, you have an adequate support frame underneath. Is the foam not rigid and strong enough to support the tracks and scenic elements without resorting to expensive plywood?

By not having a plywood deck ...

wiring would be simpler -- no holes to drill (in the wrong place), just poke a hole in the foam with a coathanger or awl;

undermounted switchmachines could be mounted closer to the surface by simply cutting a hole for it;

no worries about seasonal expansion/contraction.

There is no way I could work with a foam only layout. There are places where I need to stand on my layout. Beside, working in O gauge, it is possible to have 10 pound locomotives. For my upper deck I'm thinking about 1/2" OSB with 1/2" foam over that. The lower level is 3/4" plywood with foam or homasote roadbed.

[chateauricher]

QUOTE: Originally posted by Big_Boy_4005
There is no way I could work with a foam only layout. There are places where I need to stand on my layout. Beside, working in O gauge, it is possible to have 10 pound locomotives. For my upper deck I'm thinking about 1/2" OSB with 1/2" foam over that. The lower level is 3/4" plywood with foam or homasote roadbed.

With the larger scales and their heavier equipment, I can see where you would need the extra support of plywood.

And if you had a layout where you needed to stand on portions of it in order to reach other sections, then, yes, plywood would be a good idea.

However, what about for smaller scale (eg: HO, N, and Z) layouts where all areas can be reached without standing or leaning on the layout ? [%-)]

[howmus]

I have used everything from 1/4" up to 1/2 inch plywood on the layout. What I use depends on where and for what purpose I am using it. I would recommend that you use 3/8" plywood and keep the supports no farther than 16" apart. Gluing the plywood is also a good idea. Much of my 3/8 inch base has been down over 20 years and has not warped at all. However! The conditions in my basement stay reasonably the same year around. If your room has wide swings of temperature or (more importantly) humidity, you may want to go 1/2". IMHO 3/4 is major overkill unless you only put supports in every 4'. Consider your total cost for the construction, not just the cost of the plywood.

Have fun!

[grayfox1119]

You are correct Ray, you use what you need depending upon what your layout needs for strength. I have tables that will be 30" wide and wider. I may need to get up on these tables at times, I weigh 185#. I also want the room underneith un cluttered for staging, so my supports are every 4 feet. I also have a well temperature controlled basement location ( as you stated also Ray). This makes a big difference. There is a correct answer for each layout, but that answer depends upon all the factors mentioned by all the guys that answered this thread, bookshelf layouts to not need 3/4", table layouts of 24" or less do not need 3/4"....the layout dictates the construction design required.

[Anonymous]

Well in my area, 2" foam isn't readily available, so I'm only going to use two layers of 1/2" foam (which is available) and my layout is around the wall but is 48" wide. The walls/ceiling of the room slope inward (bonus room over the garage) so I will need to climb on top of the layout when laying track along the walls (the hidden main loop). So it will need to support my 250lb fat butt. I think I'll go with 1/2" ply with 12" joist spacing, glued and screwed.

[Big_Boy_4005]

QUOTE: Originally posted by howmus

I have used everything from 1/4" up to 1/2 inch plywood on the layout. What I use depends on where and for what purpose I am using it. I would recommend that you use 3/8" plywood and keep the supports no farther than 16" apart. Gluing the plywood is also a good idea. Much of my 3/8 inch base has been down over 20 years and has not warped at all. However! The conditions in my basement stay reasonably the same year around. If your room has wide swings of temperature or (more importantly) humidity, you may want to go 1/2". IMHO 3/4 is major overkill unless you only put supports in every 4'. Consider your total cost for the construction, not just the cost of the plywood.

Have fun!

Actually, 3/4" plywood can get kind of springy if you don't support it about every 24". In order to cut material costs, I cut the sheet into strips. Being in O gauge, that means 4" per track. In the photos above, there was less than one full sheet used to do 30 feet of railroad. In those areas where I need to climb on the layout, I just deck it, but that's only a couple of places.

[selector]

Oh well, I'll jump in myself, and add my three Cdn cents.

My layout has three 4'X8' sheets of plywood set long side by long side to make a 12' X 8' layout. The plywood is 5/8", good on one side (GIS). I have threee two-by-four 41"-high pony walls spaced 24" apart holding up the entire layout. On top of the plywood is one layer of 1" foam. I danced on that layout many times rasping foam with a wire brush, and I got lots of movement, but it was sideways, strangely, in time with my arm movements as I brushed the foam. A few diagonal braces soon fixed that!

The 2X4 ponywalls were definitely over-kill, but not the 5/8" plywood. I believe that I would have experienced some sagging if my 'walls' had been spaced another two or three inches apart.

If you want my considered advice, I would use not less than 1/2" plywood if you will rely thereafter only on the glue holding together two layers of 1/2" foam, and then only if the joists or supports are no further than 18" apart. I say this with your claim in mind that you will have to climb up on it from time-to-time.

[howmus]

jshrade, given the fact that you will have to climb up on the layout changes my recommendation to you! You would be better off, given what you are doing to use 1/2" plywood. Also get the 5 ply stuff as it is considerably stronger than the 3 ply. 3/8" plywood can be found in both, most 1/2" is 5 ply (that is, it has 5 layers of wood used to make the plywood). Again, how you are using it makes a big difference in what you should be using. Have fun!

[tsasala]

If humidity is an issue, you might want to try OSB instead of plywood. It holds up better, but I think it's usually more expensive.

I put foam directly over my frame without any underlayment. But I'm modeling HO and have no reason to stand on my layout. In fact, my layout will be hoisted to the ceiling when not in use, so weight was a concern for me.

-Tom

[cwaldman]

All it depends on is the spacing of the supports underneath. What load it is gooing to carry, over an above the normal railroad. If you are going to walk around on it then you probably will need to do one of two things. Use thicker plywood or use more suppost under it. It is probably a trade off your making by spending more on support or more on thicker plywood.

it has been recommended before to seal the wood to prevent warping if humidy is a concern.

I wouldn't recommend walking around on styrofoam of any thickness.

Cletus

[selector]

Cletus, you raise a good point. Aboslutely, DO NOT walk, kneel, even pray up on your foam sheets without using a weight-distributing length of board, plywood, or another piece of unused foam. Otherwise, your heels, tools, or knees will leave unwanted marks and marr the surface. My preference was a piece of plywood as it was stiffer and better at holding my weight in distribution.

[Anonymous]

Well, I got to thinking more about it, I'm definitely going with 1/2" plywood (well, down here they call it 15/32 but that's basically the same stuff (5 ply), my joists are 12" apart, but considering where I'll need access in the long run, I'm certainly going to have access hatches instead of climbing on top. Only issue I really have will be the hidden double tracked mainline and part of the reverse loop section, which will be out of reach from the edge of the tables, but my plan is to have that track as bulletproof and derailment free as I possibly can, so I won't have to go back there but every so often. I have plenty of room under the layout to access the back side, just have to cut in some 'hand holes' to be able to reach things. Shouldn't be too hard if I hide the holes with buildings, instead of complete removable sections.

[bogp40]

QUOTE: Originally posted by howmus

jshrade, given the fact that you will have to climb up on the layout changes my recommendation to you! You would be better off, given what you are doing to use 1/2" plywood. Also get the 5 ply stuff as it is considerably stronger than the 3 ply. 3/8" plywood can be found in both, most 1/2" is 5 ply (that is, it has 5 layers of wood used to make the plywood). Again, how you are using it makes a big difference in what you should be using. Have fun!

I would like to add to this. Check out the ply at a local quality lumber yard first. They will carry a far better grade of ply than the big box stores. Plywood, whether 3/8 or 1/2" can be found in Douglas fir graded for underlayment (3/8, 1/2 PTS or termed plugged and sanded). This is still a relativly inexpensive ply for the quality. Most big box stores will have only pine and found to be inferior.
Last week I needed 40 sheet of 1/2" CDX, my regular supplier was $.30 less than HD for fir instead of pine. All the sheets were flat w/o the curl as most lesser grades will tend to have.
Some people love these big box stores, I personally don't have the time to deal with them and then end up w/ a lesser product. I deal with lumber on a daily basis, Pull up to the lift load it and get to the job with a good product to work with for a quality job. Not All Plywood Is Created Equal...
Bob K.

[Anonymous]

I decided on 15/32" 3 ply plywood for the layout. I took one look at what was available in 3/8 at my local lowes, and really wasn't thrilled, but the stack of 15/32 right next to it looked so much better, and was only marginally more expensive ($1 more per sheet) and marginally heavier, but considerably less flex. I would've liked to have found 4 or 5 ply, but the 15/32" they had seemed like decent quality and now that I've got it temporarily placed on the layout benchwork, I'm quite happy with it. Had to install a ceiling fan last night in the layout room, and sat on top of the plywood for nearly an hour as I hooked up the fan, with no sag, and no problems whatsoever with my benchwork wobbling or anything. Once I actually screw the plywood to the frame and joists, I think it'll stiffen things up even more. Thanks for all the advice guys!

[Anonymous]

jshrade

I have a shelf railroad that is 24" wide and in 8 foot sections and is framed with 1 X 4's with 1/8" lauan glued and screwed to the top. It has 2" foam glue to that. Its stronger than most without the heavy layup. Why most people think you have to have plywood thick enough to walk on is beyond me.

Larry