To Build or Not Build a Frame?

[RobertInOntario]

I’ve made a small 3x5’ layout out of insulation foam board that I bought at Home Depot. The layout is simply set up on a portable table in the basement and I’ve operated the layout this way for the past 8-10 months. (It's a British 00 layout, which is similar to HO.)

Is it necessary to create a frame around (& under) the layout? I’ve been thinking of doing this but haven’t got around to it. This would obviously give the layout more support and strength. And, if so, what’s the minimum thickness of a sheet of plywood that I could get away with (for underneath the layout)?

The layout seems fairly sturdy as it is, so I’m still wondering if this extra step is necessary or not.

Thanks in advance.

Rob

[nachoman]

Question #1 - how thick is your foam, and what type of foam is it? If it is the blue or pink extruded type of foam 1.5 or 2 inches thick, you are probably okay going without a frame at only 3'x5' size. If it is the white foam, or less than 1.5 inches thick, I would recommend a frame. In my experience, thinner foam or the white foam is will sometimes bow slightly and needs support. The white foam isn't nearly as strong, and should have a frame no matter what the thickness.

I would not use plywood for a frame. Instead, I would build a frame out of 1x2 lumber. At that small of a size layout, I would simply build a rectangle with dimensions 2'x4', and glue it underneath the foam, leaving a 6" overhang on all sides. I would upgrade to poplar lumber as opposed to pine. It is straighter and has less knots. Putting an entire sheet of 3/4" plywood underneath the layout as a "frame" would be much heavier and not nearly as strong.

[RobertInOntario]

Question #1 - how thick is your foam, and what type of foam is it? If it is the blue or pink extruded type of foam 1.5 or 2 inches thick, you are probably okay going without a frame at only 3'x5' size. If it is the white foam, or less than 1.5 inches thick, I would recommend a frame. In my experience, thinner foam or the white foam is will sometimes bow slightly and needs support. The white foam isn't nearly as strong, and should have a frame no matter what the thickness.

I would not use plywood for a frame. Instead, I would build a frame out of 1x2 lumber. At that small of a size layout, I would simply build a rectangle with dimensions 2'x4', and glue it underneath the foam, leaving a 6" overhang on all sides. I would upgrade to poplar lumber as opposed to pine. It is straighter and has less knots. Putting an entire sheet of 3/4" plywood underneath the layout as a "frame" would be much heavier and not nearly as strong.

Thanks, Kevin -- all of this is helpful.

The thickness of foam is about 2" and it's green insulation foam. So it's very similar to the pink or blue kind, just the green/environmental version.

The frame you describe also sounds good although I may not need to go that route.

This leads to my next question or project! I was thinking -- that if I didn't need to create a frame -- I might extend the layout's length by 8" to 16" so I could add a sort of fiddle yard! I already have one siding at the left end of the layout where I can park one train -- I'd like to simply add another siding and improve the current siding.

This would obviously increase the layout's size to either 3x5.5 ft or 3x6 ft. I should have a little extra time in the next week or so, so I thought I'd try to sort out a few details before I started.

Thanks again,
Rob

[Russ Bellinis]

The only reason to use a frame would be to protect the edges from damage. To strengthen the foam so that is doesn't break, just glue a piece of luan door skin cut to the same size to the bottom of the foam. Foam is very strong, but if an uneven force is applied, or you fall or lean against it and it is not supported on a flat surface, it can snap in two. The 1/8 inch door skin will support it so that you could even put it on legs and it would not break. If you want to extend the sides, cut the door skin to fit the expanded size and glue pieces of foam to extend it. The added pieces will be supported by the door skin. Otherwise, without support, you will need to start over with a new larger piece of foam. You probably should use a 1x1 under the door skin to keep the luan from bending at the joint where you butt the foam pieces. A couple of pieces of 1/2 round molding full length under the door skin would make nice "skids" to support the layout, and protect the table you set it on from marring.

[RobertInOntario]

The only reason to use a frame would be to protect the edges from damage. To strengthen the foam so that is doesn't break, just glue a piece of luan door skin cut to the same size to the bottom of the foam. Foam is very strong, but if an uneven force is applied, or you fall or lean against it and it is not supported on a flat surface, it can snap in two. The 1/8 inch door skin will support it so that you could even put it on legs and it would not break. If you want to extend the sides, cut the door skin to fit the expanded size and glue pieces of foam to extend it. The added pieces will be supported by the door skin. Otherwise, without support, you will need to start over with a new larger piece of foam.

Thanks, Russ. This sounds like an excellent idea. I'll look into it at my local Home Depot (conveniently, only a 5-min. walk from my house!). Rob