Big Country - Walls - R9 Insulation, Roof – R23 Insulation, Floor - R35 Insulation, Slide Room Floor - R38 Insulation. Approved for full-time use I had never considered our 3450 a true 4-seasons coach but the published R factors are pretty good. NuWa publishes Roof R-14, Walls R-9, and Floor R-19 and most consider them a good 4-season rig. I do think it will depend on your location and perhaps some of the options like insulated windows etc. I would have few issues here in the Pacific Northwest as our climate is considered mild. We really like the Big Country and have been very pleased with the Heartland product and the company.
Best Wishes in your quest!