See here what "Frank" did when he built his brothers camper. He did an outstanding job on it...
Here he is doing the floor insulation
And here are the walls. See the post after it too as he sealed the gaps
Your looking for close cell foam, not the normal little round balls of Styrofoam board.
The R value will help guide you
Good luck and curious to see how yours comes out.
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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