What to do with the seams between foamboards?

[videobruce]

1/2" rigid foamboard over 3/8" plywood. Seams staggered so they are not in line with the ply 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?

[3DTrains]

Bruce - using plaster cloth will avoid the tiny cracks that tend to appear as the underlying wood support shrinks and expands (I failed to do this on my first module, but never again). If you stack foam on foam, then no need to worry - simply fill with putty and sand as needed.

Cheers!
Marc - Riverside

[wm3798]

I always cover my foam with a generous coat of Sculptamold.  Covers all the joints, and gives me a more or less uniform surface for the scenery base.  Also holds fence posts and telegraph poles better...

Lee

[DKS]

I always cover my foam with a generous coat of Sculptamold.  Covers all the joints, and gives me a more or less uniform surface for the scenery base.  Also holds fence posts and telegraph poles better...

Lee

+1

[Zox]

I use glueshell/papier-mâché, with layers of 20-pound copier paper (recycled printouts) and full-strength white glue. Glueshell has the advantage of being ever-so-slightly flexible, so under pressure (like seasonal temperature/humidity shifts) it flexes rather than cracking or powdering.

[MichaelWinicki]

Agree with Lee & David.

Sculptamold... Great product.