Using Flex-Seal on my van roof?

When I bought the ex-GRM van from Tom, we discussed the rust repairs on the drip rails, and the need to seal them somehow to prevent them from rusting again(since the van will be parked outside 100%).

I was initially thinking of using white roll-on bedliner, but it doesn’t seem to exist anymore. A friend suggested Flex-Seal - he uses it on his home’s gutters & says it lasts for years, with only occasional touch-ups in areas that get worn though. 

Here’s a pic of the van showing a couple small cracks that have already developed. 

Can anyone suggest a better product to use? My intent is to keep adding thin layers until there’s no longer a lip to catch water & it can just roll straight off the roof. 

It turned a screen door into a boat... how bad could it be...

I've used it on the roof of my shipping container/storage unit. I've been very pleased. Nearly 2 years so far. But it has some tree coverage, not constant direct sun exposure. 

I suggest 3M 08307 self leveling seam sealer.  That's what it's made for.

White mobile home roof coating.

I used spray on Flex Seal on my RV, no good. Within a year it was cracked and flaking.

I would use the 3m suggested above or a Sikaflex polyurethane caulk. 3m 5200 UV could be used also.

In reply to APEowner & java230 :

Thanks, I’ll check out both of those 3M products!

Danny Shields said:

White mobile home roof coating.

I wondered about this too, but wasn’t sure it would withstand the effects on a vehicle in motion?

I have used Flex-Seal to seal up a rearend that had a small rust perforation in it.  This be easy.

java230 said:

I used spray on Flex Seal on my RV, no good. Within a year it was cracked and flaking.

 

I would use the 3m suggested above or a Sikaflex polyurethane caulk. 3m 5200 UV could be used also.

Same, used it on my cargo trailer and it lasted a year

Ok, the 3M 08307 definitely would work, though I’d need to paint it afterwards, but I have an area of about 1/2”x1/4”x40-feet to cover. At ~$30 for a 200ml applicator I’d be looking at about $750, plus the gun needed for it. 

I didn’t find anything stating the 3M 5200 is UV resistant? However I did find the 3M 3000UV that looks like it would work? 

White marine caulk was going to be my suggestion.  Looks like you found that.  

Defender can be a good place for stuff like this.  $11.99

Fast cure 4000UV for $15.99

In reply to Pete Gossett :

Sorry its the 4000UV that is UV stable. The 5200 is, but not as much. However its much much stringer than the 400/4200 line. As in not removeable. 

I have had great luck with the sikaflex products as well. The 1A+ would probably be my go to. Again will chaulk in UV a bit, but its really flexible and stick like crazy.

Dicor 502 self leveling sealant. 

Available wherever RV supplies are sold.

It works very well and is what I used on SanFord to seal all roof openings. 

Edit to add. They also make a non-self leveling version if you prefer. 

Danny Shields said:

White mobile home roof coating.

I'd go with this as it made for outdoor use and to seal out the weather. To me Flex Seal is nothing more then the common ice and water dam roofing material.

I see flex seal on roof pretty frequently. Unfortunately often within 6 months or so of someone buying a house. The prior owner or handy man applied it. 

Good as a temporary fix but direct UV exposure it cracks and flakes off. 

In reply to Greg Voth :

That’s what I needed to hear Greg, thanks!

I found 3M 4000UV at the local marine supply place, I just need to stop by one day this week & pick up a couple tubes.