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Foam Insulation Board Sub-Roadbed

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  • Member since
    July 2017
  • 5 posts
Posted by uemjg on Saturday, July 8, 2017 10:10 AM

markie97

I have started an expansion of my layout and was planning on using 2" and in some areas 1" thick foam insulation board, the kind you buy in Home Depot or Lowes. After reading comments in the foam core discussion thread I have some concerns about expansion and/or contraction. Should I be concerned? 

Where can i get a digital or traditional book on just setting up the basics before actually laying track...for example the proper way of setting the diffferent types of foundations, track beds, etc?

 

 

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Saturday, July 8, 2017 10:26 AM

There's two potential shrinkage problems with foam:

One is the shrinkage caused by continued chemical reaction after it is initially formed.  I would expect that, if it happens, it would have a diminishing effect over time.  Hence the pronouncements about aging for 6 months.  

Now, the reaction MAY not be diminishing.  Some don't.  Consider zinc pest, and the great sadness that it can generate years after manufacture.  

But it does "feel" like the diminishing style of reaction.  Anyway, this kind of shrinkage does happen.  I have seen the results.  Hopefully, doing the six month wait eliminates the problem.

 

 

The other is continued and continual shrinkage and expansion caused by temperature variations.  It exists, also.  I saw it happen with my module, where the widths of cracks in the scenery surface over the foam changed with temperature.  The cracks widened when it was hot.  And narrowed when it grew cooler.  The module was stored in an unconditioned space.  I observed it when the temperatures ranged from 50 degrees to 90 degrees.

It seems likely that foam on a layout in a conditioned space would have minimal problems with the above.

 

Ed

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