# Plywood



## swimmer_spe (May 3, 2016)

I have 6 table legs.

I want to use a 4x8 sheet of plywood. What is the thinnest I can go without any bracing? If I were to use 2x4s for bracing, what is the thinnest plywood I can go? How do I brace it?


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## rrgrassi (May 3, 2012)

I use 1x4 every 2 feet of space. and 1x4 around the perimeter. 3/8 in ply is good.


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## raleets (Jan 2, 2011)

Call me "king of the overkill", but I used 3/4" EXTERIOR grade plywood. 
Reason? Because my layout is in a separate, heated garage which varies from 45 to 72 degrees all winter long, then pretty much stays about 75 degrees in the summer.
So far, after 6+ years, no warping or problems whatsoever. :thumbsup:


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## flyboy2610 (Jan 20, 2010)

If you are thinking of attaching the legs directly to the plywood, with no other framing, that's not a real good idea. Sooner or later it will warp and sag. Use some 1x4's to build a frame around the perimeter of the plywood, then a 1x4 cross brace every two feet. Install three legs on each side. Brace the legs to the framework with diagonal braces. It would be a good idea to run a brace from one leg on each side to the other on the opposite side. Sooner or later those legs WILL get kicked.
3/8" plywood should be fine that way.


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## swimmer_spe (May 3, 2016)

rrgrassi said:


> I use 1x4 every 2 feet of space. and 1x4 around the perimeter. 3/8 in ply is good.





raleets said:


> Call me "king of the overkill", but I used 3/4" EXTERIOR grade plywood.
> Reason? Because my layout is in a separate, heated garage which varies from 45 to 72 degrees all winter long, then pretty much stays about 75 degrees in the summer.
> So far, after 6+ years, no warping or problems whatsoever. :thumbsup:





flyboy2610 said:


> If you are thinking of attaching the legs directly to the plywood, with no other framing, that's not a real good idea. Sooner or later it will warp and sag. Use some 1x4's to build a frame around the perimeter of the plywood, then a 1x4 cross brace every two feet. Install three legs on each side. Brace the legs to the framework with diagonal braces. It would be a good idea to run a brace from one leg on each side to the other on the opposite side. Sooner or later those legs WILL get kicked.
> 3/8" plywood should be fine that way.


Mine is indoors in a heated basement.

Sounds like I am getting some 1x4s when I get my 3/8' sheet of plywood.


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## Lemonhawk (Sep 24, 2013)

1x4's. The legs need diagonal bracing even if you bolt them to the floor.


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## mesenteria (Oct 29, 2015)

I like to go as light as possible, so I use 1/2" G1S or 5/8" G1S if I can get it at a discount. It is set flush at the edges to 1X4 box framing. For either thickness of plywood, I would provide three (3) 1X4 joists equally spaced inside the box. I use 1X2 for legs, braced partway down their lengths and blocked well into the corners. 

Even better is 1X4 box open frame with some 1X2 joists set flush to the bottom edges of the outer frame members. Then, set 1.5" or 2" extruded foam board cut to measure inside the box frame.


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## CTValleyRR (Jul 26, 2014)

I'll do you one better. The minimum thickness of plywood is 0". You don't NEED it. Use of extruded foam insulation panels will allow you to have a free standing layout, self supporting, with minimal framing.

2x4 lumber is really overkill. It's very strong, but the added weight means you need to increase the rest of your structure accordingly. For strength without the weight, use a T or L girder. Glue and screw a 1x2 to a 1x3 (or 1x4) in a T or L shape so that the grain is perpendicular. Very strong, and much lighter than a 2x4.

Most people comstruct benchwork that can be used as earthquake protection. Try thinking about how light you can make it instead.


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## D&J Railroad (Oct 4, 2013)

If you want to use just the extruded foam, it may support just track and the rolling stock, but if you add scenery with buildings, wiring, plaster covering etc, it starts building up. Add to that the cuts you may be inclined to make to create rivers or indents to the land form and your foam board begins to sag. On the other hand, if you only intend to lay track down and call it done, foam board is the way to go.


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## CTValleyRR (Jul 26, 2014)

D&J Railroad said:


> If you want to use just the extruded foam, it may support just track and the rolling stock, but if you add scenery with buildings, wiring, plaster covering etc, it starts building up. Add to that the cuts you may be inclined to make to create rivers or indents to the land form and your foam board begins to sag. On the other hand, if you only intend to lay track down and call it done, foam board is the way to go.


Use 2" foamboard as the base and don't cut into it. That is your lowest level and everything else is built up on top of that. You would have to add an awful lot of stuff on that to make it sag.

Even one L girder joist in the center would be enough to support any conceivable layout weight without sagging.

I realize some of you think it's heresy not to have a bomb-proof framework, but really, it's totally possible to have a really solid layout with minimal wood. And when a 2" foam panel costs about $5 less than a comparable area of 3/8" ply, and requires less wood for support structure, it quickly becomes a cheaper alternative, too.


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## swimmer_spe (May 3, 2016)

CTValleyRR said:


> Use 2" foamboard as the base and don't cut into it. That is your lowest level and everything else is built up on top of that. You would have to add an awful lot of stuff on that to make it sag.
> 
> Even one L girder joist in the center would be enough to support any conceivable layout weight without sagging.
> 
> I realize some of you think it's heresy not to have a bomb-proof framework, but really, it's totally possible to have a really solid layout with minimal wood. And when a 2" foam panel costs about $5 less than a comparable area of 3/8" ply, and requires less wood for support structure, it quickly becomes a cheaper alternative, too.


I do not plan to live in this house forever. In fact, in about 5 years, I plan to move to a nicer house.

I know foam. I know how strong it can be for it's weight. However, I also know how durable it is.

I may lay a piece of foam as a first main layer, but it is not going to be the structure.


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## fcwilt (Sep 27, 2013)

I would not use less than 1/2" ply. 

I have used A-B or A-C depending on what they had in stock.

With a good 1x4 frame you could also use 1/2" MDF.

Frederick


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## CTValleyRR (Jul 26, 2014)

swimmer_spe said:


> I do not plan to live in this house forever. In fact, in about 5 years, I plan to move to a nicer house.
> 
> I know foam. I know how strong it can be for it's weight. However, I also know how durable it is.
> 
> I may lay a piece of foam as a first main layer, but it is not going to be the structure.


I think you misunderstand. You need a framework of wood. Your entire structure can't be foam. Make a frame of 1x3 with a couple of joists. Folks carry modules made of nothing more than that back and forth to train shows all the time. 

If you're dead set on an all wood structure, fine. I just want to make sure you've given the alternatives a fair shake, and aren't just assuming it has to be wooden construction because you've never heard of doing anything else.


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## swimmer_spe (May 3, 2016)

CTValleyRR said:


> I think you misunderstand. You need a framework of wood. Your entire structure can't be foam. Make a frame of 1x3 with a couple of joists. Folks carry modules made of nothing more than that back and forth to train shows all the time.
> 
> If you're dead set on an all wood structure, fine. I just want to make sure you've given the alternatives a fair shake, and aren't just assuming it has to be wooden construction because you've never heard of doing anything else.


When I am done, my layout will be an L that is 12 feet by 8 feet.

I would rather go with wood, and when you bump it, it is not likely to break off like foam does.


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## CTValleyRR (Jul 26, 2014)

swimmer_spe said:


> When I am done, my layout will be an L that is 12 feet by 8 feet.
> 
> I would rather go with wood, and when you bump it, it is not likely to break off like foam does.


I'm obviously not communicating the concept very well.

I can bump into my layout all day long, in fact, i can whack on it with a hammer and i won't harm the foam.

How can i do this? The foam is inside a wooden frame. Make a box of 1x4 liumber with a few joists (1 or 2 for every 2x8 foam panel will suffice). The base layer of foam nestles inside the box, with its surface level with the top of the framing boards. An L girder joist will be almost even with the frame underneath. Additional panels or sections of foam can be glued on to the top to add height; a thin hardboard or lauan plywood fascia will protect that foam as well.

This construction is rigid, light, and very portable, especially if you frame each individual foam panel and use carriage bolts and wing nuts to join them.


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## Nikola (Jun 11, 2012)

CTValleyRR said:


> This construction is rigid, light, and very portable, especially if you frame each individual foam panel and use carriage bolts and wing nuts to join them.


Or, use hinges to join adjacent sections. Remove the hinge pin to break it down.


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## swimmer_spe (May 3, 2016)

CTValleyRR said:


> I'm obviously not communicating the concept very well.
> 
> I can bump into my layout all day long, in fact, i can whack on it with a hammer and i won't harm the foam.
> 
> ...


Or, screw 1x4 around the outside, and 3 more spaced 2 feet apart. 
Which sounds easier?
Cost wise, plywood would be cheaper for me. I have priced it out.

So, in the end, yes I could do it, bt a simpler, easier, and cheaper build would be plywood and bracing.


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## Lemonhawk (Sep 24, 2013)

I'm in foam group. 1x3 (or4) outside box with a few 1x2 cross pieces. I use that thin luan plywood sometimes as the base if I can only find 1/2" foam. (difficult to find thicker foam in FL) When its all tied together its very strong, yet when broken down for transport its very light.


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## CTValleyRR (Jul 26, 2014)

swimmer_spe said:


> Or, screw 1x4 around the outside, and 3 more spaced 2 feet apart.
> Which sounds easier?
> Cost wise, plywood would be cheaper for me. I have priced it out.
> 
> So, in the end, yes I could do it, bt a simpler, easier, and cheaper build would be plywood and bracing.


The 1x4 (or whatever) frame would be a given in any case. You're not considering using unsupported plywood, are you? Even 3/4" ply is going to sag over an unsupported 8' run.

I won't argue with your "simpler, easier, and cheaper" analysis, but to me it smacks more of trying to justify an already-made decision. Whatever. Your layout, your rules. Good luck.


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## swimmer_spe (May 3, 2016)

CTValleyRR said:


> The 1x4 (or whatever) frame would be a given in any case. You're not considering using unsupported plywood, are you? Even 3/4" ply is going to sag over an unsupported 8' run.
> 
> I won't argue with your "simpler, easier, and cheaper" analysis, but to me it smacks more of trying to justify an already-made decision. Whatever. Your layout, your rules. Good luck.


Plywood with 1x4 underneath to support it. The legs will be 4 feet apart.

I want to use wood for the base for many reasons. I am trying to find out how to make it strong enough. 

If I ever plan to make a portable layout, I would consider foam, because, as you said, it is lighter.


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## rrgrassi (May 3, 2012)

When I build modules, I use 1x4 and 1 inch thick extruded foam, and a thin luan plywood for the base and I use HO size track screws for the track and cork.


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## Mr.Buchholz (Dec 30, 2011)

3/4 inch thick plywood is what to use. I wouldn't go with anything less thick than that. 

-J.


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