Question regarding lap sealant

Westend - good and informative post - thanks. I also have a new trailer on which it was pointed out to me that there are some areas on the roof where the factory-applied sealant was "not sufficient" and that they could scrape all that off and replace it properly (at a cost of maybe $600!). After inspecting the roof with the adviser I said thanks for bringing this to my attention but I will do this myself. ;) The areas were as the OP described - joints at the roof-front and roof-back end faces.

I have Dicor self-levelling lap sealant already and my intent was, and still remains, to use this for small touch ups on existing sealant. Now that I see this thread and the comments regarding Eternabond, and after checking out their website, it is clear that I need to get some Eternabond as well.

jbres wrote:
yea sorry what I used is "self leveling sealant".. Can anyone fill me in on the difference between the "lap sealant" and "self leveling caulk"? If I don't use the eternabond, what type of sealant should I use that will seal the entire 2" span?

A lap sealant is a sealant that is used for sealing two surfaces, one of them overlapping. A self-leveling sealant is one that has low viscosity when applied so that it can spread over an area before curing.

I know at least Dicor labels their product "lap sealant" and it's primary use on RV's is to seal other areas, much like a caulk where two surfaces meet. In the traditional definition of "lap sealant" it isn't being used as one.

The OP doesn't believe Eternabond is better (I was there once) so the best sealant to use to cover a 2" mess of sealant is Dicor self-leveling sealant. To control the added mess created by spooning more sealant over the spread area, you could tape or cut the unwanted off.

FWIW, I come from a construction trades viewpoint on sealants and never saw the kind of sealing process that was done on an RV roof until recently. I've seen a lot of pictures in this Forum of vent->roof joints, around vent stacks, and on the front or back wall->roof joints. The sealants must have been applied with a machine assisted gun applicator and the excess sealant used is probably to insure adhesion to the surfaces. But what a freakin' mess. There really is no reason to have 1/2" of sealant piled on top of a joint. The usual maintenance procedure is then to get up there and spread more across the top, trying to seal small cracks or edge areas that have come loose.
I don't have a rig with these furrows of sealant but if I did, I'd be up there pulling it off and replacing with an adequate sealant, probably Eternabond because it works so well.

and I have a TPO roof. Is this eternabond good for TPO?

yea sorry what I used is "self leveling sealant".. Can anyone fill me in on the difference between the "lap sealant" and "self leveling caulk"? If I don't use the eternabond, what type of sealant should I use that will seal the entire 2" span?

Me too on Eternabond. Btw- you need to use self leveling caulk on roof penetrations and seams. Lap sealant is for vertical surfaces. Glad to see you are keeping an eye on it. The best preventative maintenance one can do with an RV.

X2 on EternaBond. Once you put this stuff on it's there for life.
EternaBond

Putting eternabond over the top of the existing "thin" factory lap sealant?
Doesn't seem it would be a smooth finish with the eternabond

Google EternaBond and use it per directions on the seams. You'll pretty much never have to use caulking again.

on front and rear seams I strongly recommend eternabond 4" seam tape, followed by another helping of dicor on top of that. You will never have to mess with it again