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Steve Hericks

I’m a former RV engineer. There are MANY issues when specifying a true 4 season camper but it has to start with an effective the envelope. Without that, no ‘options’ will make it an effective 4 season vehicle. 1) Insulation: Most manufacturers try to sell ‘4-season insulation’ but few do whats necessary. First, understand how to measure the effectiveness of ‘insulation’ by ‘R-value’. This is a combination of insulation type and thickness. The best insulation types are foams, specifically, polyurethane (spray foam) is ~R-7/inch. Poly-iso cyanurate is about R-6/inch and Extruded Polystyrene or XPS is about R- 5.5/inch (not expanded polystyrene or EPS which is also called ‘styrofoam’ which is R-4/inch). Fiberglass is about R-3.5/inch and is often used. Since RV walls are necessarily thin, you need the best insulation you can get. The best you can probably hope for is a 2″ wall with ~R-11. 2) Insulated aka double pane glass. This is usually an upgrade but it is essential. This is the only way to reduce heat loss and condensation. You need to know specifically the R-value of walls, floors, ceilings and windows to make an informed decision on the true ‘4 season’ capability. Do not rely on an opinion of what seems to work for someone else. One big neglected issue that I will not go into is condensation inside the walls. This destroys insulation. Steve