Interesting Observation Of Foam Board


N

Nightwing

Member
My new setup is coming along well. I recently noticed that the long edges of 2" hard insulation foam are bowed down a bit. Enough so that track laid near the edge is distorted.

I built a frame of 1X6's sized so that the foam would drop in. The inner side of the 1X6's has 1X3's all around, with 1X3's spaced equally length wise. The foam board rests on the 1X3's and is glued to them with construction adhesive made for gluing foam board. The board sits about 1" below the frame which protects the edges of the foam.

I put two coats of gray primer down over the pink foam and two coats of grass green acrylic paint. It looks very good and will lend itself to landscaping and scenery.

I don't know if the foam had a draft angle on when purchased or this is something that has occurred since the application. Not a big deal. I can shim the track out at the edges if necessary.

So, a tip I figured out. If you have an open gondola or flat car, lay a small plastic bubble level on top of it and run your train around slowly. The level will show you the high and low spots in your track. Much easier than manually laying a level on the track every few inches to check for irregularity.
 
Nightwing said:
The inner side of the 1X6's has 1X3's all around, with 1X3's spaced equally length wise.
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What is the spacing of the cross bracing? Curious because I use a similar set up for my modular units only I use 1x2's instead of 1x3's.

I like your idea. I might make a flat car with a bulls eye bubble level on it.
 
There are two runners lengthwise in the open section. They are about 15" apart. Basically, one on each side and two in the open gives support of 4.

I used 1X3's because they are actually 2 1/2" tall and the 1X6's are actually 5 1/2" tall. Therefore, the 2" board sits 1" below the frame which prevents a train falling off the layout and it protects the edge of the foam. The whole assembly is reasonably light and sits on a ping pong tabletop. It has handles on each end, so my wife and I can easily lift it up and set it against the wall, should the urge to play ping pong becomes an issue. I will post a pic shortly.
 
Nightwing said:
Well, can't figure out how to bring pix from my computer to this forum.
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When the picture is on your computer -

Open a post.
Type your text.
Click on the picture icon - its the third from the left in the box just to the right of the smiley face, the square between the world with the X and the film strip
Click the "From Computer" tab in the pop up box
Click "Browse"
Navigate to where your picture is.
Select the file and click OPEN
Click "Upload file(s)"
 
train 004.JPGtrain 001.JPGtrain 003.JPGtrain 002.JPG
 
It must be something to do with storage....maybe not stacked well. Even 1" thick extruded foam is fairly stiff, but it will sag by about 1/8" over three feet if left unsupported. Joists on 18" centers should be good for 1" extruded foamboard. The 2" stuff is very stiff.
 
Selector said:
It must be something to do with storage....maybe not stacked well. Even 1" thick extruded foam is fairly stiff, but it will sag by about 1/8" over three feet if left unsupported. Joists on 18" centers should be good for 1" extruded foamboard. The 2" stuff is very stiff.
Click to expand...

That's almost certainly it. People tend to underestimate how much sag can occur just from the weight of the materials over time.

For minimum weight, the various specifications for mobile modular layouts are probably the best choice as they're usually the minimum possible weight that still has adequate durability. If that's too much weight, I'd probably consider just breaking the layout into two parts for half the weight per side and put some supports in for stacking.
 
I don't quite follow you. The entire setup weighs less than 40 pounds. There is no stacking and the underside of the foam is supported lengthwise by 4 1X3 stringers. It may have been the acrylic paint. Still, not too difficult to deal with. I will shim the track as necessary to keep it flat.
 
I glued and painted almost the entire surface of my first layout, on which I used 1.5" extruded foam board. I used PL300 to glue the foam board onto 5/8" plywood, so that might have made a difference. In any event, even though I painted and glued liberally to cover it all with ground foam, it never did deform for me. What I meant by incorrect stacking is that the material may have been stressed at the place where you purchased it. If you are certain it was very flat at that time, and that the changes are new, I would agree that there must be another reason.
 
Looking at your pictures, and not knowing what sizes these sheets are cut from, if it's rounded off on both the long sides and square cut across the ends, then that's how it's produced i.e. in continuous runs of that width and cut down to shorter lengths. Just a manufacturing "thing". As insulation it's not a priority to be dead flat. What was it like on the other side of the sheet?
 
I thought it was reasonably flat when I bought it at a big box store. They have them standing up in racks. They are scored on one side to make it easy to snap in half. You have to be very careful handling it or you end up with two pieces.
 
I can see quite a few dimples and imperfections in the surface, didn't get the top one off the foam block they were sliced from? Sort of the cover sheet.
 
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