# Foam base Board



## captaintom (Jun 15, 2016)

I am planning to use 3/4 inch rigid foam board for my layout. It will be on 1 x 3 railings roughly 12 inches apart. There is a slight amount of give but I don't think this is an issue. Has any one used this and did you have any problems. I like the foam because it is light and deadens the sound. I prefer it over Homesote. 

Thanks for any thoughts.

Capt Tom


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## Bwells (Mar 30, 2014)

3/4" foam over 12" on center seems a tad bit weak. Maybe at least some 1/4" ply under but I have never done that so give it a shot.


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## Lehigh74 (Sep 25, 2015)

I would use thicker foam or, like Bwells recommended, glue it to plywood. I have used ¾”, 1’ and 1-1/2” thick rigid foam to make scenery. In the 1” and ¾” thicknesses, it is not uncommon for the foam to be slightly warped. In 1-1/2” thickness it’s flat.


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## traction fan (Oct 5, 2014)

*Foam on wood, or not.*

Captaintom;

I have to agree with the prior posts. Either use much thicker foam; or put wood under it. The plywood option gives you a surface to mount switch machines, wiring and other needed stuff.
Using thicker foam, and no plywood, helps keep the layout light weight. 
Besides supporting the weight of our scale locomotives; the base of our layouts needs to be rigid enough to stay very straight. warping from temperature and humidity changes can turn a flat mainline into a near roller coaster profile. I saw this clearly when the club railroad was video taped. The video showed just how humped our line was. A good way to prevent this is by bracing the plywood table surface and especially the sub-roadbed with additional lumber. On my N scale layout all the track roadbed is built on a sub-roadbed that is designed like a deck girder bridge. With bracing all along the line, and all wood painted, I have no warping. My layout is in a garage, with plenty of temp. and humidity change.
To keep the layout light, I use thin, (1/4") luan plywood glued into L-girder, or box girder shapes. It is extremely strong and rigid; yet very light weight. Below is a photo of a box girder filled with Styrofoam. To get an L- girder shape, just use any two adjacent sides.

regards;

Traction Fan:smilie_daumenpos:


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## captaintom (Jun 15, 2016)

*Foam Base Board*

Thanks for your quick replies and suggestions. They sort of confirm my concerns.

I am going to use 1/4 plywood under the foam. It will add some additional rigidity and still maintain the sound deadening advantage of the foam.

I'll post some pictures as I move along.

Capt Tom


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## Guest (Jun 16, 2016)

I used 1" extruded styrofoam with no plywood, supports spaced about 18" apart with no problems. It is plenty strong. I used it for my N scale layout for about 10 years. I switched scales and I've used the same benchwork for heavy O gauge with no problems for about a year and a half. Total life of the benchwork is more than 10 years with no sagging.


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## captaintom (Jun 15, 2016)

*Foam Base Board*

Thanks Country Joe

I suspect that I could get away with just the foam board. I am being conservative adding the plywood.

One of my reasons is that I need more rigidity. I will have the layout (about 81/2' x 5' in one area) on floor sliders so I can get around to all sides for access. The plywood will prevent torquing/twisting when I move it. For a similar concern the legs are well cross braced. The dicey part is to still allow easy access to the underside of the layout.

Capt Tom


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## Guest (Jun 16, 2016)

You're welcome Captn. We generally build our benchwork much stronger than it needs to be but I think that's better than not building it strong enough and having problems down the road. 

Good luck with the build and please keep us posted as you make progress.


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## traction fan (Oct 5, 2014)

*Sound deadening and rigidity*



captaintom said:


> Thanks for your quick replies and suggestions. They sort of confirm my concerns.
> 
> I am going to use 1/4 plywood under the foam. It will add some additional rigidity and still maintain the sound deadening advantage of the foam.
> 
> ...


 Sound deadening depends on isolating the track from the "sounding board" of the traditional 4'x8' plywood base used on many layouts. Foam is an excellent sound insulator but, like the Homosote, traditionally used as roadbed, it can be easily, accidentally, bypassed. When we add rock-hard ballast, dirt, and other scenic material; glued together; it sometimes provides a continuous sound path from track to plywood. As long as any noise has to travel through bare, or painted, foam; there should be no complete path. 
I agree with your decision to use 1/4" ply under the foam. The sheet of ply, alone, however will not make the layout all that much more rigid than foam alone. I don't know what framing, or fascia you plan on using. To make the table really rigid, I would glue the ply to a 1"x3" grid frame that runs the full length, and width of the plywood. This creates the L-girder shape, which won't bend.
Fascia can also be used to provide rigidity. If it is firmly fastened to the plywood, and frame. You may also want to seal whatever wood you use, with paint. This can help prevent warping.
Whatever you decide to build, we'd love to see photos!
Traction Fan


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