Exterior caulk question

donn0128 wrote:
Cracking is probably being caused by excessive flexing at the joint. It could be anything from loose mating parts to weak frame, to thermal expansion of disimilar materials. I think it is time you do some serious inspection to root out the cause

The cracks are not large enough for me to think it is frame issues. These are hairline cracks, but enough to concern me about water getting in. Thermal expansion, maybe.

If the caulk was not so brittle, and if it were not occurring on most all areas of the trailer (windows, door, etc) I might consider frame possibility. As with all trailers, there is flexibility involved and I'm sure that is a factor.

Unless you've had experience with it, you will never realize how good the 3M 4000 and 5000 series adhesive/sealants really are. Sure, they are expensive (and I'm a cheapskate), but it's all I will use. I've used others, and now I 'throw rocks' at everything except these 3M products. I don't have time to do a selling job on these great products, but I figure if someone is truly wanting to know which is the best, they will do their own research.

Cloud Dancer wrote:
Unless you've had experience with it, you will never realize how good the 3M 4000 and 5000 series adhesive/sealants really are. Sure, they are expensive (and I'm a cheapskate), but it's all I will use. I've used others, and now I 'throw rocks' at everything except these 3M products. I don't have time to do a selling job on these great products, but I figure if someone is truly wanting to know which is the best, they will do their own research.

thanks, I will research.

A big con for me was that 3M doesn't come in clear color. Pretty low density, too, and it takes forever to cure. Won't stay in vertical crack, will leak out. Maybe there are some additives for fast cure, don't know, but when working on my marine things with 3M 400 it was a royal pain because of white color and low density.

Over the years I have tried a number of caulking compounds. I started with Geocell but im not sure of the compound type. A roofer told me to use it. It lasts the longest with less mold. I also used latex caulks they are easier to apply and clean up but turn black with mold quicker than the Geocel. They also fill in small cracks if you applyva thin coat. If you apply a lot it will crack. The Dicor self leveling is good on the roof and resists mold better than the latex caulks. I like the 3M 4000 that Will mentioned and use it on my boat. It is more of an adhesive than the other caulks. It is is difficult to remove but the 5000 series is even a stronger bond if you want to bond something to you roof and have it water tight at the same time. I tend to make a mess when I caulk so I like the water based caulks better. But any caulk that you do yearly is better than the best stuff that you apply and forget about. At least that is my experience.

Gjac wrote:
Over the years I have tried a number of caulking compounds. I started with Geocell but im not sure of the compound type. A roofer told me to use it. It lasts the longest with less mold.

Must be Geocel ProFlex RV. This is what the OP is trying to avoid, as it's difficult to remove, and when I think of it - doesn't appear to be valid excuse.

I tried it too. It is similar to renowned Dicor, only skins a bit faster - for this reason I would prefer it to Dicor on vertical surfaces. It doesn't shrink (Dicor shrinks A LOT), and doesn't bubble. Same as Dicor, it becomes harder after a few years and is difficult to remove.

dryfly wrote:
I have previously used Geocel ProFlex caulk for the outside of my fifth wheel. I found it was very difficult to remove the old caulk when it came time to re-apply. I also found that the caulk itself is not the easiest to work with as it is oil based and is quite messy to apply, particularly when you are just trying to apply a small bead. It just dries too quickly!

Since my trailer sets outside it seems like in about 2 years after applying new ProFlex it starts to get very hard and the flexing of the trailer, as it travels down the road, causes very small cracks in the caulk bead.

Has anyone tried a common latex caulk to fill in these small cracks? If so, what are results?

You're post could have been written by me, and frame flexing is not the issue...

Has anyone tried a common latex caulk to fill in these small cracks? If so, what are results?

Latex type caulk was all we had for sealing a trailer before the new gen caulk became available in the late '60s/'70s era.
From '60 to '65 I worked in a mobilhome/rv factory mostly in frame up and metal exterior/doors/windows stations.
Latex caulk will dry hard and crack in a couple of years. I wouldn't use it on my RV as a sealant.

My '97 5th wheel trailer has most of the OEM lap sealant still left on the roof. I have no idea what brand but its still flexible.

I've used self leveling Dicor on the roof since '05 era when needed and the last time I had to reseal a vertical joint was with Dicor 551 I believe. That was in the '09 era. Its still flexy but I have't tried to remove it.

It may be that you are applying too small of a bead of sealant and that is why it is cracking. What size bead of caulk is being applied? Are you using a solvent to clean up the installation of the caulk?

Almot wrote:

Gjac wrote:
Over the years I have tried a number of caulking compounds. I started with Geocell but im not sure of the compound type. A roofer told me to use it. It lasts the longest with less mold.

Must be Geocel ProFlex RV. This is what the OP is trying to avoid, as it's difficult to remove, and when I think of it - doesn't appear to be valid excuse.

I tried it too. It is similar to renowned Dicor, only skins a bit faster - for this reason I would prefer it to Dicor on vertical surfaces. It doesn't shrink (Dicor shrinks A LOT), and doesn't bubble. Same as Dicor, it becomes harder after a few years and is difficult to remove.

It was Geocel 2300 that I used. I never tried the Profiles but probably similar.