Washing the roof (with the correct products) is always a good start and using the correct protection product for the roof will prolong the life of the roof as well.
" lgray " ... is correct about " Don't skimp with the caulk"
- For what it is worth -
However, a very experienced RV teck advised me when it comes to caulking the best prep to clean prior re-caulking would be to use white gas (camping gas).
If used on the roof areas: ONLY ON The Caulking if use on the roof. Do Not Get it on the Rubber Roof .
It evaporates quickly, effectively cleans the back dirt and preps the old caulk for recoating.
>This means any volatile oils or liquids must be used with caution on the rubber roof areas. <
..IMO... Where as 'mineral spirits' is a more oily nature it leave a slight film and may interfere with adhesion.
Again, the same RV Teck advised me against using mineral spirits for prepping caulking on the sides of the RV for that very reason.
Personally I have found that a damped rag with white gas is more controllable to use for prepping or re-caulking than mineral spirits that may spread onto the rubber roof.
[The fear is that any volatile liquids that come into contact with the rubber roof may inter fear with the roof membrane itself or the cement holding it down]
Hope this helps
'07 WildCat 30 RLBS ~ West Coast Edition ~
Trail Air - Tri Glide Pin Box
2000 F350 DRW 7.3 Diesel Lariat 89k miles
Edge programmer, 4" SS exhaust turbo/back
Vancouver Island, B.C., Canada