I’m trying out some 2" 2X8 extruded polystyreme foamboards on plywood as a table top. On this I will be using cork roadbed.
Just like my DIY drywall, I have some edge-mating problems. For various reasons the edges are not always flush. They can be up to 1/64 to 1/16 out of level in some spots. The foam sculpts very nicely, but if i try to level the edges by sanding the high one I will end up with hollows (tried it).
So I was thinking that filling is better than sanding to get some levelling. What would you recommend.? Perhaps drywall mud? More latex caulk? I’m open to suggestions. I would like something more durable than drywall mud. Latex caulk will work, but can’t be sanded or finished properly
I just used good ole latex caulk on the seems I had with the foamboard. You can smooth it out with a putty knife. It doesn’t have to be perfectly flat. The cork roadbed will lay down fine over that. And the scenery ground cover will cover any flaws.
You need to be using a large sanding block to keep from making depressions. A 1x4 or 1x6 about as long as a full sheet of sandpaper. Then you can caulk the seams.
I have a sea of foam on my layout. There were lots of uneven edges. I used a rasp to level the terrain at the joints for my cork roadbed. It did look gouged out but I rounded off some of the edges and it soon looked like natural landscape. Railroads cut and fill and do what ever is required to get a long level roadbed.
I do use drywall Dap to fill other dips, but only under the cork directly. I will then used ballast or rip rap or other means to give the area a realistic shoring up. I think when we start up on our first layouts, we fuss to much about messing up the terrain while building. It’s nothing a little cup of dirt or a tree won’t cover up. [:)]
On a separate note if you want to take your track from the cork to the foam for a yard situation. I use a rasp and just lower the cork into the foam.
Latex caulk should work fine, but you could also consider spray foam insullation to fill in the spaces. It dries much like the rest of the foam. Also, can be used to add more shape to your terrain, whether filling gaps or any other spot. Sculpts very similar to the sheets once dry.
Where I have large gaps, between my sections, I jam in a scrap of wood, then level it off with some caulk. For smaller gaps I use scraps of foam left over from cutting pieces to size. And where it isn’t really a gap at all, just the caulk works fine.
I use drywall spackling compound (mud), shimming or caulk. The Compound did crack slightly at the joint after a full set of seasons but this had no effect on the WS roadbed. The caulk is of course the most flexible but all three work.
Roadbed (cork or Woodland Scenics style black foam) can address minor sins of difference in height, with the proviso that it is alwayws a good idea to avoid having pieces of flex track (or sectional track) meet exactly at a joint of the lower surface.
But if we are talking measurable differences then all of my instincts tell me to address those differences with shims below the pink foam rather than try shaving, filling, or applying other surface textures to the top.
I’m having a little trouble visualizing your issue. I understand the problem with the lip and what is happening with that. I’m missing why things have to be perfect, particularly in areas that will have scenery.
I’ve used extruded foam for my last two layouts. Just as is your case sometimes the edges aren’t level. I make a few passes with a rasp or sand paper and then smooth things out with joint compound. It does hold up. If you elaborate further maybe we can be of more help.
If you go to the progress photos of my site I think you’ll see some shots with the foam.
Thanks for all the info, gentlemen. I am with you on the general priciple that perfection is not what I should be looking for, and that some gouging and scenic work will assist in the problem.
Lance, my issue is that I have benchwork with several foamboard sheets where the 8 foot edge is up to 1/16 out of level with the adjoining/butting board. When I lay my cork roadbed across these, the effect is not good. However, I have had good success in the past two days with some silicone II caulking which will not shrink. I have just put it on with a wide trowel as if I were drywalling, but in several very thin layers, building it up. I did not want to create a hump as this could not be taken down with sanding like drywall compound could. So far it works well.
In the yard area I have found some wide sheet cork made by the same roadbed company expressly for yard areas.
