It is called delamination. It is caused by water intrusion into the wall. Unfortunately it is not a warrantable item. The top of the slideout must be inspected several times a year for damage.
2004 Chev Silverado Duramax optioned past the max. 2009 Jayco Eagle 308 RLS 765 watts of solar, 6-6 volt batteries (696 amp hour), 2000 watt (4000 surge) whole house inverter.
140 days boondocking in 2016
211/2015, 196/14, 247/13, 193/12