Storing your RV under a roof-type cover or within a building when the RV will not be used for an extended period of time is always a good idea when this option is available to you.
When you must store your RV outdoors during periods of non-use, you also have the option of using a temporary cover that is draped over the RV, then fastened onto the RV tightly. Many of these covers have a DuPont Tyvek top or roof panel and Polypropylene side panels.
Many RV owners prefer to cover their RVs with the drape-over style covers to protect the surfaces and finish from UV breakdown, dirt, leaves, birds and other airborne contaminants. On the other-hand, many RV owners feel that to cover an RV with the drape-over style covers may lead to chafing and that chafing can lead to rubbing of paint, decals and other finishes. This camp prefers the trade-off of the effects of a cover that may rub off their finishes to the need to work harder to restore the finish of an RV that is exposed to the elements during the period of non-use.