# What to do with the seams between foamboards?



## videobruce (Jun 15, 2011)

Not really a "design" question, but using 1/2" rigid foamboard over 3/8" plywood with seams staggered so they are not in line with the plywood seams.

Can/should the seams between the foamboards be covered over like drywall seams? If not, isn't movement a issue and the resulting cracks??


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## sstlaure (Oct 12, 2010)

By the time you put dirt, ground cover, etc down, even if it does crack all you're going to end up with is a crack in the ground (pretty common in the real world.)

I've heard of some guys mixing colorant into their plaster so that when/if it cracks, you don't see white.

I plan on using drywall compound.


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## videobruce (Jun 15, 2011)

> I plan on using drywall compound.


Between the seams??


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## raleets (Jan 2, 2011)

videobruce said:


> Not really a "design" question, but using 1/2" rigid foamboard over 3/8" plywood with seams staggered so they are not in line with the plywood seams.
> 
> Can/should the seams between the foamboards be covered over like drywall seams? If not, isn't movement a issue and the resulting cracks??


I used Woodland Scenics Foam Putty, applied with a small putty knife. Allow to dry for a day, then use a sanding block to level off.
Worked great! You can then either paint over it or apply gound covers.
Bob


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## tjcruiser (Jan 10, 2010)

You can use latex caulk between the seams .. squish panels together, and let it ooze out. However, when it does, wipe up all of the excess with a warm, damp cloth before it dries.

TJ


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## sstlaure (Oct 12, 2010)

videobruce said:


> Between the seams??


Yep, I don't plan on having many truly smooth seams but rather natural contours that will hide the seams. By the time I apply the drywall compound, paint and apply grasses, ground-cover - you'll never know what's underneath.


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## videobruce (Jun 15, 2011)

This will be N scale so I am somewhat concerned about cracks.
I didn't know if I should just let it go until it comes time for ground cover.


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