A roller coaster, and indeed any system of wheels, symbolizes your heart, circulatory system and emotions. Wheels are circular so are a pun on circulatory system.
A roof symbolizes your brain – the top of your body. For example, a roof on fire warns of a threat of stroke. Fire symbolizes your circulatory system so this dream warns of damage to your brain (roof) caused by your circulatory system (fire).
Rooms in houses and buildings signify specific things.