I use this caulk for the flat part of the roof. I go up there and touch up any areas the show cracks or where it might pull away a bit at seams. As far as the membrane goes, I clean it once a season and apply uv Protectant.

https://www.amazon.com/Dicor-501LSW-...dDbGljaz10cnVl

https://www.amazon.com/Rubber-Roof-T...s%2C108&sr=8-5

There are different materials for the roof versus the rest of your RV.

The roof requires a sealant compatible with an Alpha "TPO" roof. From Alpha's website at https://alphallc.us/products/roofing/ (click on the FAQ tab):

Q: What type of roofing membrane does Alpha currently carry? A: Alpha’s SuperFlex roofing membrane is a TPO, which stands for thermoplastic polyolefin.

The Alpha website contains a lot of related information on the proper materials, etc. Note that Camping World (or Gander RV) sell a branded version of Alpha called "Superflex". https://www.campingworld.com/super-f...ite-80294.html Also note there is a self-leveling (for horizontal surfaces) and a "Non-Sag" version for vertical surfaces.

For around windows and other places, a good exterior (clear) silicone caulk will work. Ensure all the old sealant is removed and the surface is clean prior to application.

There is a lot of information on sealants already documented here on the forum. See https://gdrvowners.com/forum/gdrv4li...hing-the-forum to learn how to search for it.

Howard

I have used Sikaflex 715 for the roof where self leveling is needed. I used a heat gun and solvent to remove the original sealant and applied the 715 in place of the old sealant. I used it on my old rig, it lasted for years and when I sold it, the sealant was still soft, pliable and not one bit powdery, unlike the Dicor which dries stiff and cracks. Also the Alpha Systems 1021 that comes stock on Grand Design, powders up quickly and also cracks.