Black/Raised Roof Lines

John:
Thanks for the thoughts. Actually, the black spots are along RAISED areas, rather than indented areas. I realize the photos aren't high def, but wanted to keep them small for the posting. In reality, the black lines actually highlight raised areas that are only as wide as the black lines. I can see/feel the raised areas as if I'm feeling a beam underneath. Are you saying that the construction should be such that starting from outside to inside: there is the vinyl covering then deep to that should be plywood, and then deepest is a beam? Ken

I wonder if glue they used pushed up where the plywood seams are. When you step on either side of the line, can you detect a flex there? Do you think that mildew is the black substance?

I sent a post earlier but it must be lost in cyber space. I have the same thing on my Spree. Its been sitting outside for three years. I noticed it (the black lines) the first year I had it. My thoughts are the ac vents leak a lot of air into the attic space, unless you take them off, and seal them the best you can. I believe the cold ac air inside meets with the aluminum trusses and condensate. Same in the cold months. Warm air inside meets cold outside and again condensates. The black has slowed down since I sealed the duct at the vents, but has not stopped. If you find out more I would be interested to know what exactly is going on. Your are right the black is extremely hard to remove. I gave up. I was afraid I would damage the skin on the roof.

I have a 2015 spree connect with the same problem only worse because I live in N. Alabama which is more humid and more conducive to mildew growth.  Mine has it around the edges of the roof as well.  Surface mildew is easily killed and will vanish before your eyes with just chlorine bleach and water mix. I've used it to clean roofs for 30 plus years.  I have tested small areas with Chlorox Cleanup and the surface mildew goes away almost immediately but the larger round black spots remain untouched.  My guess is there is a film or skin on the membrane that the mildew has somehow managed to get under so the bleach can't get to it. The raised areas you mention appear to me to be adhesive used to stick the membrane down that was never rolled out properly.  I don't think it has anything to do with the mildew.  I have the same thing on mine with some raised areas that have no mildew.  Anyway It doesn't look to me to be anything that threatens the integrity of the roof so I live with it.  We'll see what your dealer says.

abs-
That sounds great to at least not waste the cool air! Thanks,
Ken

Hi everyone:
Thanks for all of the suggestions thus far. Here's an update: I sent the photos and description to both the dealer and KZ for comment. I just spoke to the dealer and he thought the lines might represent the junction between sections of Lauan, which he says are always 4' x 8.5'. I just measured between the lines and sure enough: the lines are EXACTLY 4 feet between. He thought it could have something to do with the taping material that joins the Lauan sections and offered to send the photos to the factory too. We'll see who gets a response first! I also just tried Chlorox Cleanup and no improvement in removing the black material. The dealer suggested denatured alcohol which I will try later. Finally, I just removed a round A/C vent to see if I could see the space between the duct and the attic space. I'm a little confused as it seemed that I could see the metal top of a vent, then 2 opposite sides but can't feel anything on the opposite sides. We also have a large square vent in the salon which shifts the flow of air from that big unit to the smaller round units. So...not sure if/where I would put the rubber to seal off the attic???
Ken

very interesting, I got the same thing on the roof of my 2016 Durango 2500.

Hi Everyone:

I've continued my research and pretty much have it solved to the best of the industry's knowledge.  First, as a review, the lines DO represent the junctions where the 4 x 8 feet Lauan boards meet along the roof such that the lines are every 4 feet.  The boards meet on top of the aluminum trusses.  I saw that the roofing material is called "Superflex" and made by Alpha Systems.  I called Alpha Systems and they were extremely helpful in discussing the issue on the phone and confirmed that they supply the material to KZ.  The representative confirmed that the company had seen the black blotches before and by testing, know that the blotches represent mold accumulating along the Lauan junction lines.  They suspect, based on cutting out sections of roof from RV's that the mold accumulates related to a waterproofing material at the edges of the Lauan boards.  However, they don't know how this is actually happening.  They suggested the following:  Paint on bleach (I used Clorox in a jug), allow to sit for 10 minutes, then remove with a rag or scrubby brush.  I did this and it worked PERFECTLY!  They said that this procedure will actually keep the mold away for sometime and she also said that the problem does not present any structural issues.  Now that I think back, I think the 'raised-ness' of these cross lines has always been there, representing the Lauan junctions over the trusses.  I don't think this is a problem but have sent a follow-up note to KZ.  Finally, I removed my A/C vent covers inside the trailer to see if cold air was escaping into the attic like someone here suggested but I saw that my duct is the typical rectangular duct that connects the other ducts in the unit and doesn't seem to leave any space for cold air to get into the attic.

If you want to see a fun video of installation of the Superflex, check this out:  www.youtube.com/watch?v=yeFDO7IVhsk

So, it seems the problem is resolved for now and just waiting to hear back from KZ to be sure the slightly raised lines are normal for the Lauan junctions.

Thanks for everyone's suggestions,

Ken
Rhode Island

Below is the link to a file:  the steps to clean the black lines from Alpha Systems.