I am building a new layout, I used 2" foam board in my previous layout, I am thinking of using 4" of foam board on certain sections of the layout. Anyone out there using 4" of foamboard and does it create any unforseen issues.
For reasons of inexperience and not thinking, I ended up with over 4" of foam for my layout base. I have had no structural problems with it despite lack of planning.
Acutally I see no need for more than a 2" base. In HO that gives you 14 1/2 feet of depth to the bottom of the foam, which should be plenty of clearance for most things you need. If you are having inclines and trains pass over trains, you can build up where necessary, but still on the 2" base. Should you want deeper cuts than the 2" offers, you can cut out the 2" and then attach pieces underneath for your depth.
I have some hills made with multiple layers of foam and they also have had no problems.
Good luck,
Richard
For hills and mountains you can build up layers of foam as thick as you want. After carving and forming the final landscape most folks will cover the foam with a layer of Sculptamold, plaster cloth or paper towels dipped in hydrocal.
My original plan was for a small switching layout, and one of the areas had a lot of track well above street level, so I went with 2 layers of 2" foam, expecting to cut the top layer away in places, plus even dig into the lower layer in spots.
I ended up moving and having room for a bigger layout, but since I had that section built (just benchwork), I did the rest of the layotu the same way.
DON’T DO IT
It complicates switch machine installs, pushing feeder wires through, and it’s noisier than my previous layout, which was just a single layer of foam. If you are going to build on a flat base, a single layer of foam is fine. You can use things like the Woodland Scenics Inclines and Risers for parts of the track that need to climb, and for scenery formas you cna stack as many layers of foam as you need,
Another issue is that for a given base height, with 2 layers of foam, the benchwork is at least 2" lower underneath. That does make a difference in getting underneath, and in what sort of things you can put underneath the layout for storage (couple of plastic cabinets I have fit, but only if the wheels are removed. If the top layer of foam was removed and the layout raised such that the top level was at the same height, the wheels could go back on.).
–Randy
Our portable HO scale modular layout is built on 4" foam blocks measuring 2 x 8 foot. Very light and easy to move around. One person can easily handle a module. We set it up on fold-up picnic tables.
Since all the switches are Peco, we didn’t need to mount any switch motors. Feeder wires were easy to install by drilling a hole through the foam. All of the wiring was put into grooves burned in the bottom of the foam with the tip of a Weller soldering gun, and then covered with caulking so there are no wires dangling loose anywhere.
But I would NOT try to build a permanent layout on foam that thick