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Topic: Caulk for roof seams (Read 720 times) previous topic - next topic

Caulk for roof seams

I'm going up on the roof to do some projects. While I'm up there I would like to re-caulk the end caps and several fixtures.

Whats the current suggested caulking type/brand?
1995 U320C SE 40'
Jeep 4x4 Commander - Limited - Hemi
"The Pack"  Yogi and Diesel our Airedales -  Charlie our Boxer/Akita mix. Gone but NEVER forgotten Jake our yellow Lab.
NRA Law Enforcement Firearms instructor - Handgun/shotgun
Regional Firearms instructor for national Armored Transp. Co.

Re: Caulk for roof seams

Reply #1 –
Dicor Self-Leveling Lap Sealant, IMO.

Not cheap but by far the best product for the application  It stays pliable, sags slightly to fill seams, and sticks to what it is supposed to.  Easy to remove a decade later.

I spent a lot of time earlier this year removing silicone caulk from my RV roof, and reapplying the correct product.
Matt B
1998 u-320

Re: Caulk for roof seams

Reply #2 –
For 20 years we use GE Silicone, usually clear. Understand some use other products. Silicone is not paintable. Prepare surface with denatured alcohol.

Re: Caulk for roof seams

Reply #3 –
Don't use silicone.  I like 3M Marine Adhesive Sealant 4000 UV for roof top stuff. Strong bond, removable if needed. Dries quick enough to not attract dirt.

The 3M 4200 Marine Adhesive Sealant Fast Cure is a different formulation, cures slightly faster especially at the surface and is a bit stronger bond and harder to get apart but possible.

I did my rear seam, remove all of the trim, clean it and the roof joint as best you can. I put down painters tape close to where the trim was fitting when reattached, gooed it up, put 4000 on every screw and screwed it back down.  Cleaned up the excess, smoothed out the roof to trim joint and pulled the tape.  Looks good.  Wear latex gloves.  WD40 works pretty well for cleanup.

And then I painted the roof with anti skid, insulating polyurethane paint right over the cap trim strips.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Caulk for roof seams

Reply #4 –
Quote from: Barry & Cindy –
For 20 years we use GE Silicone, usually clear. Understand some use other products. Silicone is not paintable. Prepare surface with denatured alcohol.
This is what I used as well, per Keith Risch's recommendation.
1987 Grand Villa ORED
2001 U320 4010

Not all that wander are lost... but I often am.

Re: Caulk for roof seams

Reply #5 –
Over the years I have found that 3M products are hard to find fault with.
1995 U320C SE 40'
Jeep 4x4 Commander - Limited - Hemi
"The Pack"  Yogi and Diesel our Airedales -  Charlie our Boxer/Akita mix. Gone but NEVER forgotten Jake our yellow Lab.
NRA Law Enforcement Firearms instructor - Handgun/shotgun
Regional Firearms instructor for national Armored Transp. Co.
 

Re: Caulk for roof seams

Reply #6 –
Ohh gosh for the love of all things please don't ever use silicone to as a flashing caulk on an RV. That is all that the caulk is, a flashing. The seal that really keeps the water out of anything is where the two surfaces come together with a mechanical force (screw, or rivet etc) and a sealant between the two surfaces. The main reason to use things like Dicor is that it is REMOVABLE. Ever tried cleaning old silicone off a surface, nightmare. Ever cleaned off old lap sealant, easy!

One other note is to always try to use the same material on top of existing. If you are unsure of what is on the joint currently the best thing to do is remove the old flashing sealant and clean thoroughly then apply new sealant.

This advice comes from years of experience repairing and rebuilding water damaged RV's. I have seen all kinds of gunk on a seam.  Also check out  James the AZ Expert and he has a ton of great videos showing how to do things. AZ Expert on Youtube