The choice of materials to build a module is very important to the longevity, usefulness and enjoyment of the module or layout. Unfortunately, the do-it-yourself nature of model railroading and the desire to economize on the “hidden” parts of a module can be counter-productive. The cost of the model railway frame or structural is minimal compared the value of the modelers time and effort, the monetary costs of track, scenery, rolling stock, DCC system, buildings, etc. On modules, high quality materials and precise construction become a necessity to ensure the module ends interface properly and is interchangeable with others at an exhibit.
At minimum, the poor selection of module materials will make significantly increase the effort and trouble setting up a module or sectional layout. Worst case, it can require a finished module to be discarded because of failure or the need to rebuild a module’s defective framework.
Modules and sectional layouts use manufactured panels, solid wood or lumber and foam board for their construction. The following is a general overview of each of these materials.
Manufactured Panels
Oriented Strand Board – OSB is also referred to as waferboard. OSB is made from flat chips of wood that are pressed and glued together. OSB is structural as the chips are oriented in a cross grain pattern like plywood. OSB has a smoother surface than construction grade plywood, but much rougher than cabinet plywood. OSD does not have the interior voids that are common in today’s construction grade plywood. It is not recommended for module frames, as the OSB chips tend to delaminate with handling. Some have used it for module tops with varying success. OSB will swell when exposed to many of the water based glues, paints, and plasters used in model railroading. OSB is also referred to as chipboard, beaverboard, and I believe, aspenite in the UK.
Particle Board – Particle board uses much smaller wood chips or flakes than OSB. Visually, the individual wood chips will appear to be the consistency of coarse saw dust. Particle board is not recommended for modules because it is highly susceptible to moisture damage, is very heavy and is not a structural panel. Particle board is not designed for carrying loads and sags badly in unsupported spans. Modules and layouts from particle board tend to be very, very heavy.
Medium Density Fiberboard – MDF has the finest texture of the materials discussed here. The wood chips in MDF are “fiberized” and are of a very fine grain. A lot of painted moldings is made from MDF because the fine grain makes it very machinable. Like particleboard, MDF is heavy and is not a structural panel. It use in module is not recommended.
Hardboard – Masonite is the trademarked name for this product. Hardboard has a very smooth flat surface on one side with the reverse side being textured or in a waffle pattern. Hardboard is available in tempered and un-tempered. Tempered is much harder. Hardboard is typically used for skyboards and fascia as its flat smooth surface takes paint and photo backdrops very well. Hardboard has also been cut into long strips and used for spline sub-roadbeds.
Construction grade plywood – Todays construction grade plywood can have significant interior voids. This means the outer plys have areas that are unsupported by the interior plys. Specifically, screw heads can compress and crush the outer ply through the void area until supported by another interior ply. North American plywood typically has fewer, larger plys, so this can be a significant problem. It is one reason why OSB is favored in house construction for floors and sheathing. When selecting plywood, count the number of plys or layers and look for voids that show along the edges. More plys are generally better.
Cabinet grade plywood – Baltic birch plywood is another name for this product. It is generally imported from Europe and has more plys than North American plywood. It is faced with birch veneer, making it ideal for paint or stain finishes. It typically comes in 5 foot square sheets. It is generally considered the best, and most easily available in North America.
Marine Plywood – This plywood is expensive because it has a voidless interior and two good exterior plys, usually A/B. An “A” ply meaning there are no defects. A “B” ply meaning any defects have been removed and repaired with football shaped patches. It may can difficult to find. If available and within your budget, it is highly recommended.
AraucoPly – Arauco is made from radiate pines grown on plantations in South America. It appears to be a very good product as it has more plys than typical North American plywood and the outer plys are of a higher quality. Several years ago, there were some problems with pieces warping after having been removed from the bundle and cut. There have also been some old reports of the plywood delaminating. This is a very promising product, so inquire locally and determine if these are still issues before purchasing Arauco.
Luan plywood – Laun, or sometimes luaun, is made from a tropical hardwood. It somewhat resembles true mahogany in color, but is not mahogany. It is commonly used in house construction as under vinyl sheet floors (linoleum) to provide a smooth, flat surface. Luan is typically used in grid, waffle and torsion box type modules and may be the protective perimeter in foamboard modules and sectional layouts. When purchasing laun plywood, be aware there are some very cheaply made grades on the market.
Homasote – Homasote is a compressed paper product used in home building for soundproofing and bulletin boards. Model railroaders have used these properties to build sound deadening sub-roadbeds that take rail spikes well. It can be locally difficult to find. If this is a problem, use the homasote.com website’s where-to-purchase feature to find a local vendor.
Solid Wood or Lumber
Salvaged wood – Wood salvaged from old pallets is particularly unsuitable to module building. Wood pallets are typically disposable, and made from thinner, lower quality wood that is not kiln-dried that is more likely to split, twist or warp. Salvaging used wood with nails usually loses its economy when replacing saw blades ruined by hidden nails. When thinking about salvaging wood, is the resulting material of a size and quality that would be worth purchasing? If not, your time and effort would be better spent in other areas.
Construction grade lumber – Most layout and many modules, like Ntrak, are framed with construction grade lumber. If you are able to individually select boards with minimum knots that are straight and true, lumber can work well. Usually, the boards on top of the pile have already been sorted through and rejected by others. If your vendor does not allow you to select boards, it is likely these sorted to the top materials are what you will receive. The use of construction grade lumber also creates a separate problem caused by the over-sizing of individual pieces. Larger pieces of lumber are heavier, making the module more difficult to transport or work on. The massive the lumber, the more difficult it is to control the warping and twisting that occur with temperature and humidity changes. There are several grades of construction lumber, with the higher quality materials being more expensive.
Cabinet grade hardwood – Hardwoods, like oak and maple, are usually heavier and more expensive than softwoods, like pine and fir. Because of their weight and expense, hardwoods probably most suited for trim, molding and end plates or interfaces on modules. Vertical grain or “quarter sawn” boards provide more dimensional stability than flat sawn boards.
Rigid Foam Board
Expanded Polystyrene – Expanded polystyrene is made up of thousands of beads of white foam and is also known as “beadboard”. Cheap coolers are made from expanded polystyrene. Beadboard is not typically recommended for use in layouts or modules, but seems to be used because it is cheap or remnants are available from remodeling. The beads come apart and are difficult to clean up because of they hold a static electricity charge. Beadboard is widely used by many.
Extruded Polystyrene – Also known as foamboard. It has a uniform foam consistency and usually has adequate structural and compression strength for use in layouts and modules. Typically, it is pink or blue, but other colors are available. The colors vary by the boards manufacturer, pink for Owens Corning, Blue for Dow, etc. One color is not better than another. Be aware of two potential problems with foamboard. First, it does not deaden sound, but can increase sound levels caused by the trains apparent drumming across the surface. Occasionally, you will find some foamboard that is slightly thicker than the stated dimension. Neither are huge problems, just potential issues to be aware of when building a module. Foamboard can be used as a module or layout top as well as being the material carved into mountains and other terrain.
Polyurethane and Polyisocyanurates – These are typically not used in model railroading as they are typically backed with vinyl, paper or foil. These foam boards do not have adequate structural or compression strength for use in layouts or modules.
This is an overview of some of the commonly used materials available for the construction of modules, dioramas and layouts. Because of the various grades, species and prices, it is a buyer be aware situation. Not only in pricing and product selection, but building like a cabinet maker. Cabinet makers select parts based on their intended use and structural requirements. They don’t use one product or one size to build an entire cabinet. Cabinet makers select the product most suitable to the task at hand. Frames need to be strong. Fascia and trim need to be attractive. The module or sectional layout needs to be light.
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