Most of the risks posed to an RV during storage are from UV light, moisture, and weathering. Knowing the dangers to watch for as well as how to avoid them is the key to safe storage.
UV and Weathering Damage
Roof membranes on the RV will suffer severe degradation over time thanks to UV and sun exposure. Weathering from rain and hail only speeds the process. The membrane may crack, peel, or begin separating at the seams. The older the RV, the more prone to these problems it becomes.
UV damage and weathering don't just affect the roof membrane, either. Seals around rooftop vents and other penetrations, such as skylights and AC units, will also begin to crack and peel from prolonged exposure. Even the seal between the roofing material and the RV siding is at risk of UV and weathering damage. Each of these spots is a possible water intrusion site.
Moisture is a concern as the roof membrane and roof seals begin to degrade. Moisture from rain or simply humidity in the air will begin to seep in around the broken seals and cracking roof membrane. Most RVs have a lightweight plywood shell beneath the membranes and siding. Once moisture gets in, mold and wood rot will destroy the main framework of the RV.
It's important to note that moisture can be a problem even if the roof and seals are in good condition. Vents that aren't properly closed can let rain into the RV, leading to water damage, trapped moisture, and mold inside the RV. Over time, leaves and other debris collected on the roof can also hold moisture longer, resulting in mildew stains or even leaks in the membrane.
Storage Protection Measures
Fortunately, these concerns and damage can be avoided through proper storage. Unless you have a sheltered place with no overhanging trees to store the RV on your property, an RV storage facility is the best option. Look for a facility that provides either enclosed or covered storage. Enclosed is preferred, as garage-style units will provide the most protection from the elements. Covered is second best as these protect from UV light, weathering, and rain.
If uncovered storage is the only option, then use a tarp or RV cover for protection. Opt for a tarp or cover with a reflective surface so that heat isn't absorbed, as this can dry out seals. Leave the ends open so air can circulate beneath the tarp. You should also leave open the end vents on the RV to allow air to circulate inside, as this cuts down on condensation without allowing rain into the RV.
Contact an RV storage facility near you to learn more about storing your RV safely.