I automatically figured (and bought) 3/8" plywood for my N scale 'around the wall' layout;http://cs.trains.com/TRCCS/forums/t/193229.aspx Now I'm thinking about using foam board which I've never used before. I know it's popular as a 'fill' material for mountains or just to raise the area for a river or stream 'cutout', but I see many using it for the base itself. Ok, since this is a somewhat large, narrow and long around the wall layout in N scale, what do you guys think of using; just plywood? just foam board? foam board over plywood? Also, what thickness of foam board? Lastly, how about humidity and expansion and contraction due to temperature swings in a northern unheated basement?
My previous layout was just foam, 2" think. Worked great. No issues in the basement because the extruded foam does not appreciably change due to changes in humidity. This time I went with a layer of 1/2" plywood underneath the foam. It's in a spare bedroom this time but the same thing would hold true if I had a basement, it's not going to move, shrink, or expand. I had no problem with the wood benchwork on the precious layout expanding or contracting and pulling loose from the foam. It's more the humidity thant he temperature, temperature generally stayed fairly consistent sicne the basement was almost entirely below ground, but the humidty varied greatly, in summer even with a dehumidifier runnign 24/7 it got quite humid, in the winter is was VERY dry down there.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
It's really up to you and depends on what you are going to model. If your layout is in a city setting, you can just use the plywood as a base. If your layout is going to be a country setting, I would use a layer of foam. That way you can carve down for some rivers and shallow valleys. One half inch thick should work for N scale. If you are going to model a mountain setting, go for thicker foam. (I glue the foam on top of the plywood.)With a flat surface, you can always build up, but you can't cut down easily unless there is some foam there. And if you are going to use foam, get a good quality hot wire cutter. I use the Tippi foam tool.http://www.sceneryexpress.com/prodinfo.asp?number=PC4774
And I also have the WS hot wire cutting tool.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
If you're going for grades, and want smooth transitions, an underlayer of plywood (which I refer to as subgrade) will allow you to form them with ease when cookie-cut to shape. I'm a bit hesitant about trying to make vertical curves in foam board. Also, having a plywood `cookie' gives something solid to screw into when installing risers Westcott fashion (screwing up from below.)
My own right-of-way consists of a layer of cookie-cut 1/4>3/8 inch plywood supported by risers, a layer of thin extruded foam (sold as fan-fold underlayment) and a full-size cardstock track template, all fastened together with latex caulk. Flex track or wooden ties for handlaid specialwork is secured atop the cardboard template with grey caulk, which will hide `holidays' in the future ballast.
Since the foam I use is thin, and sculpted to roadbed shape, I mark sheet stock with that cardstock track template and cut it with a utility knife. It has no problem conforming to vertical curves when secured to the plywood subroadbed. I'm sure that, left to its own devices, the foam would break at the maximum stress point of the vertical curve.
Chuck (Modeling Central Japan in September, 1964)
Just foam as a base, and for elevations Woodland Scenics makes elevations easy with foam incline starter pieces. Would not go back to ply for anything except I use little pieces as bases for my ground throws as I like to attach them with screws, others though just glue them to the foam.
I built my ost recent layout with just extruded foam over open grid 12" on center. No problems.
But if I had it to do over again {and I will when we move and I have space to build bigger} I will put the foam over 1/4 luan plywood, to have something to "bite into" for things like undertable switching machines, or table top ground throws from caboose industries.
I also choose just 1" extruded foam and built it up with WS risers/incline systems, but would use TWO layers of 1" foam to get even further "depths" than I can get with the 1" {can only carve so deep as is so thin!}. Two inch thick I think would be a bit overkill, but one inch parts glued on top of the base whole one inch should work, and then on top that have the WS risers/inclines.
I would STILL stick with only 1 or 2% inclines maximum as I learned the hard way and tore up two layouts learning that 3 and 4% grades DO NOT WORK!!! DO NOT be fooled!!!
Just my experiences, hints and advice.
-G .
Just my thoughts, ideas, opinions and experiences. Others may vary.
HO and N Scale.
After long and careful thought, they have convinced me. I have come to the conclusion that they are right. The aliens did it.