Most of the time I found the old insulation had come loose from the doghouse. If you have ever been through the shops at the factory, you would see sawdust in the air everywhere. Some of the guys are careful and clean the surface before gluing things together, and others just slap them together. Glue will always stick to the sawdust first. Object of the story. Clean the surface before gluing anything together. I did the doghouse on my 1999 Pace arrow six years ago and the insulation is still holding.
1998 Pace Arrow 35 ft. F53 Ford V10 2012 Honda Civic toad
15 year motorhome service manager. 3 popups....2 travel trailers....5 motorhomes....loved them all.