Foam

[ndbprr]

Has anyone gone beyond using foam for the horizontal base of a layout to using foam for the vertical supports under the layout and eliminated the wood? From an engineering calculation standpoint it is quite conceivable if box beams are used instead of solid components. I'd be interested in anyones results pro or con.

[dknelson]

I was interested in the recent letter to MR from a fire expert who raised a fire safety issue using foam to cover walls (it was in reaction to a recent article advocating using foam for a wall covering). It made me wonder if there is also a fire issue with using large amounts of foam on the layout. Anyone know more about this?
Dave Nelson

[Anonymous]

Foam is rather expensive to be using as legs. I'm sure it can be done, but just taking the cost of a sheet of 2 inch foam board and making 2X4 by 4 foot "boards" from it would cost about a dollar each. So it's in the same price range of framing lumber from the volume / price standpoint, but you would need more of it. I'm using 1 and 1.5 inch PVC some and it works good, but it's still more expensive than good old wood 2X2s if you had to go out and buy them new. FRED

[ndbprr]

I wasn't thinking about solid foam - sorry. If I were to make a box beam of foam I would use 1" material cut in 4" widths which would reduce the cost and the weight considerably over wood. A brief lesson in beam construction if I may. the only purpose the vertical member serves in an I beam is to hold the two flanges in place. The combination of one flange in compression and one in tension is what gives the beam its strength. Believe it or not a solid 4"x4" is not as strong as a 4" box beam made of 1" x 4" lumber. Scrap 1" foam can be found at home consruction sites where it is a hazzardous waste material because it doesn't biodegrade. the same effect and probably not as good could possibly be done if string (rope, wire, cable) could be fastened from one end of a slab of foam to the other end with a fulcrum in the center and sufficient tension pulled into the string tooffset the sag in the foam eliminating supports in most areas. In essence an upside down truss bridge. I am planning a railroad that would run for all practical purposes diagonally accross a basement with the staging behind it. I am trying to develop the most open and easiest construction I can and just working through some thoughts.

[Anonymous]

I'm sure what you are saying would work, but around here one never sees scap foam at construction sites. If I did I would build mountains from it! That's why I use recycled pvc pipe and pallets for legs. I also use pallet planks to make a L legs with 3 or 4 screws and it's strong and cheap. Thing about foam would be price for glue to make the box structures and the what if you fall or trip into your layout or roll into a leg while underneath wiring? Or kick a leg walking by? Will the foam survive the sheer stresses sideways? How about cell collaspe during long terms of loading? Will the layout slowly sink to the floor? I am leary. FRED

[MACKINACMAC]

QUOTE: Originally posted by dknelson

I was interested in the recent letter to MR from a fire expert who raised a fire safety issue using foam to cover walls (it was in reaction to a recent article advocating using foam for a wall covering). It made me wonder if there is also a fire issue with using large amounts of foam on the layout. Anyone know more about this?
Dave Nelson

I read the same response in MR. I spoke with the building inspecter in my town and he said the only real danger in the foam is the toxic fumes it gives off when it burns.

[ndbprr]

good points on the damage. I'm getting too old to be hauling large havy modules into and out of basements following moves! guess I'll just have to make them smaller.

[Anonymous]

If weight is the factor using a 2" foam top with light wood framing and PVC pipe legs are pretty light. I estimate a 30" by 8 foot HO module weighs 50 pounds and is too long for 1 person to really carry anyway. It's easy for 2 people to carry it. FRED