Silicone and caulk

[normthenomad]

I  am on my second motorhome and in the process of removing a lot of silicone. I was a liveaboard cruiser for fourteen years on a 37' sailboat. Silicone or caulking will not stop water when applied around any fixture or seam. The only way to make it water tight is to remove moulding,vent or whatever the culprit is and re-bed it as it was originally. There should be severe punishment for anyone who runs a bead of caulk/silicone around every seam they can find no matter how neatly it's done.Water WILL find a way in.

[Rickf1985]

AMEN to that!! Silicone is the four letter word of RV sealing.

[Fearless1]

What is the best product for sealing outside seams, i.e., where the side meets the top, on an RV? I was headed out the door to go to Lowe's and get some caulk when I decided to check the Forum and saw your warning and Rick's "Caution" about silicone. Guess what I had intended to buy.  i??   D:oH! W% W% W%

[classicrockfanatic]

I believe the gentlemen before, were referring to the folly of silicone application, over its sealing properties. Silicone works great for many applications, provided you prep the seams correctly. But if you just run a seam on top of an old bead, it will fail. Its important to remove the molding, thoroughly remove any old sealant, clean the bonded surface, and apply the sealant in as continuous a length as possible.


I would suggest prepping with acetone, for unpainted, or hidden, metals. Or Isopropyl 99% ( rubbing alcohol ) for composites, synthetics, or wood.

[CapnDirk]

OSI Quad!!!!


It replaced Vulkem as an exterior sealant.  I've torn  adjoining wood trim and Hardie siding apart removing pieces.  It won't let go.  And available in a few different colors.

[Rickf1985]

Silicone is ok for in the bathroom and that is it. I never holds up on the outside of an RV and then you can never put anything over where it was. This is what I use now, Polyurethane.  http://www.loctiteproducts.com/p/17/26/pl_seal_dws/overview/Loctite-PL-S40-Polyurethane-Window-Door-and-Siding-Sealant.htm

Just keep in mind that prep is everything. And when you caulk the caulk has to go all the way into the joint, no airspaces.

[Rickf1985]

Capn, I would not want something that is permanent like that. What if you need to remove the window or door? Or the trim? What you are talking about is a adhesive/sealant.

[CapnDirk]

It was not my intent to suggest mounting a window or door (under a flange)  you would never get them apart     But for something that you can knife through.


Another problem with the silicone, is that if someone used it before, it's hard to get rid of, or put something over the top.

[khantroll]

I second the OP's thoughts, even though I have recently been guilty of using silicone. My coach was covered in the stuff, and I've been slowly cleaning it off as I've properly fixed trim and what not. However, I'm getting read to replace the last few areas of rot, and on my rig I have to do exploratory work before I do surgery. So I used acrylic on the seem I pulled loose because it will possibly be a couple of weeks before i can actually do the work.