Could be a mobile home, or a cheaply built or renovated house. My Uncle Kell and Aunt Julie built a house in 1965, that had Masonite panelling in most rooms, and Marlite in the baths. My uncle worked for Masonite in Laurel,MS at the time, so got a discount on the materials. Unfortunately the house was destroyed by fire in the late 80's. Went fast, as those products have little or no fire resistance.