Cracks in fiberglass siding

The problem is caused by gassing of the fiberglass due to heat exposure. It happens mainly in the darker areas of the motorhome. My 1997 Imperial had it really bad although my 2005 Panther has it in a few places. Nothing can be done with it except to replace the entire side which is around $25k per side. Hardly worth it.

Gjac wrote:
This is called crazing in the composite industry which was quite common years ago on FG boats, chopped fiber polyester parts and even composite molds. It is caused by the gel coat being put on too thick which initially makes the product look good(more shiny) until the sun heats it up. Pure resin expands 40 times that of the fiber glass substrate and has little strength. The FG won't move so the resin cracks. Usually this shows up in the radius areas where the resin can pool up. As others have said there is not much that you can do this. I would try to sand the surface in one area to see if the cracks go all the way down to the FG and try to repaint. A good laminator will put no more than .020 of gel coat on. Is it on both sides of the MH or just one side?

Thanks for the info! My FG hasn't cracked yet but it's a concern to me when sitting in the Arizona sun!

I have a similar issue with crazing on the curb side of my Camelot. Mine is in the fiberglass so no inexpensive fix is available. :(

This is called crazing in the composite industry which was quite common years ago on FG boats, chopped fiber polyester parts and even composite molds. It is caused by the gel coat being put on too thick which initially makes the product look good(more shiny) until the sun heats it up. Pure resin expands 40 times that of the fiber glass substrate and has little strength. The FG won't move so the resin cracks. Usually this shows up in the radius areas where the resin can pool up. As others have said there is not much that you can do this. I would try to sand the surface in one area to see if the cracks go all the way down to the FG and try to repaint. A good laminator will put no more than .020 of gel coat on. Is it on both sides of the MH or just one side?

This is what Winnebago used to call "sidewall etching". I had it on a journey. Winnebago told me the only way to fix was to refinish and do a full body paint. BIG BUCKS. I don't believe painting is a "permanent fix. Have a Newmar product with the same problem even with full paint. My sidewalls have been replaced. The problem is with the material itself. The same thing was supplied to numerous different brands so they all can have the same problem. Supposedly the new product from about 2008 /9 does not have this problem. Good luck with a fix.

It appears that these are cracks in the gel coat, which is the first coat of colored fiberglass resin that is sprayed in to the mold. I do not know of any permanent repair that can be done.
You could sand and fill the cracks and then have the exterior painted, but I am sure that there would be no guaranty that new cracks will not appear below the paint.
This sounds like a factory defect, since everyone with a fiberglass sidewall coach does not have the same problem. On a 6 year old coach, that is long since out of warranty, I would not expect the factory to step up and acknowledge that there was a problem. Perhaps one of the decorative "wraps", that are now gaining popularity on auto's, trucks's, and RV's, may be one answer.

I have a uv issue on the white sections of my 2005 Itasca it looks similar to your second pic I don't have cracking (yet)? the only thing that cuts this is a 3M cleaner/wax for boats that I have found with a power buffer it is a lot of work and it only lasted one season and it's back.