Hello, I am constructing my first real layout. My current plan is two 2x6 foot modules joined around an 18 inch curve in N Scale. I was planning to use Extruded Polystyrene Insulation Board for the top of the layout either 1/2 inch or 1 inch. What sort of support structure do I need. I don’t plan on using much if any plaster products for the scenery. I do however to use lots of scratch-built styrene structures with total thickness in some areas possibly reaching 0.1 inch. I had considered L-Girder construction but after some reading have started to think L-Girder would be overkill for simple foam. My current thinking is to space 1x2 girders every 24 inches underneath the foam and screw them together 12 inches from the edge to 1x2 stringers. I would attack the 2x2 legs to the 1x2 girders. Any suggestions?
http://www.railwaybob.com/Modules/ModConstr/ModConstr01.htm has about the best module assembly instructions I have seen. The 6" nominal sides (5.5" actual) provide room under the 2" foam for wiring and switch machines, and are sturdy enough to be moved to displays.
I would put the stringers on the outside instead of in from the edge. For my layout, I used 1x4 for the outer framework, and 1x3 for the rafters going across. The bottom edges of all the pieces line up, so the rafters are depressed 1 inch. The foam goes inside the frame, which protects the edge of the foam and gives the outside a more finished look. I spaced my rafters at 16 inches, but I’m using 2-inch foam, I’ve got more plaster scenery and the total layout size is 5x12 feet.
For this layout, which is a free-standing table on legs with casters, I also added diagonal cross-bracing to keep the corners square. Overall, though, it remains very light and it’s still easy to push around, even on carpet.
This topic has been the subject of a number of threads in this forum over the last month or so. I’d suggest you do a search of the forum under this subject matter. I am about to start on a new N scale layout in my basement and have considered Homasote over plywood vs. extruded foam insulation for my bench-top base. My last layout was Homasote glued to 1/2" plywood with yellow carpenter’s glue. This worked well with the cookie-cutter method to get different track elevations.
If you want to use extruded foam insulation as your base I’d suggest building your module frames from at least 1x3" or 1x4" lumber to get sufficient strength and stiffness in the frame. You might want to consider putting the cross members of the frame on 16" centers rather than 24". I would attach at least 1/4" or 3/8" thick plywood to the frame as a base to which you’ll glue the extruded foam. This will give you a solid base for the foam especially if you are going to use only 1/2" or 1" thick foam.
From what I’ve read earlier in other threads in this forum it is that unsupported extruded foam tends to be very noisy. This may or may not be a problem in N scale.
Thanks for the replies. Looks like I’ll be doin something similar to what you’re talkin about MisterBeasly. I drew up plans to incorporate what I had talked about minus the stringers, plus 1x4s that sit under the foam. A thin plywood or other substance will A. Provide protection and B. Provide a great control panel surface for my DC later DCC layout.
Thanks
Foam is a great way to go! The box girder style of benchwork works fine. There really is no need for the L-girder system, unless you want to support you trackwork on risers. On the other hand building track elevations with foam and securing trackwork directly to the foam or with roadbed is simple and very straight forward. The remaining landscaping is really nothing more than building up and down from your base foam.
Two warnings that I will pass on (I’ve made this mistake)
1)) Place your girders on 16" centers as opposed to 24" to give better rigidity / strength.
2)) Use at least 1" foam (build up from there with the 1/2"), again for better rigidity / strength. And…The additional initial depth of the foam will also give you the ability to do some landscaping into that layer.
Thanks, I was intending to reduce the 24" to 18" just to make the math easier. I will start with 1/2" foram, but will end up putting another layer underneath. A 4x8 sheet of 1/2" extruded foam in my area is $9 USD kinda high considering I’d need 2 sheets. My design allows me to use only 1 half-inch sheet. for the entire layout. I plan to use the 1/2" sheet to get me started and up and running, then pull it off the wood, and glue down a 1" sheet.
I’m doing a similar structure as this except I’m putting 1x4 flat on the bottom flush with the side stringers and using 2" foam topped with 3/32" birch plywood to give any surface mouting screws something to grab onto for HO track.
