Water on rubber Roof

Hi JK1,

Your pictures help show what you are talking about and a few things that still may need to be discussed. As I stated, I restore older water-damaged campers.  I'm not a shop for hire; I have a somewhat extreme retirement hobby in repairing campers for a host of friends and family. I am now on my 16th water-damaged camper, so I will pass along what I know to help you as a fellow camper.    I'll refrain from telling you what to do with your dealer or Keystone.

I tried to find your camper on the Dutchmen site and have yet to find it; maybe you can tell us the year and model; a new camper may be a year or two older.  Better, post a link to your camper on the website.  The larger Coleman Lantern's are here, https://www.dutchmen.com/product/coleman-lantern#standardsOptions   The smaller Coleman here, https://www.dutchmen.com/product/coleman#standardsOptions   Neither of those campers seem to line up with the roof shot you sent by the vents in the roof. 

I wanted to confirm the roof makeup; the larger Lantern uses 3/8" OSB decking.  The smaller one, well, it doesn't say what they use.   Your camper, being smaller, may or may not use 3/8" decking, which is for direct walk-on roofs.  Yours may be a non-walk-on direct roof without support, which needs a tarp placed on the membrane to protect the membrane and small pieces of plywood over the trap to span the rafters to service the roof.   If you know for sure your roof is a full walk-on roof, please confirm this. 

Now, to your picture.  I drew on it so that we could talk about it.

The depression is not in a normal ponding place.  Here is where the roof decking, need to know, comes into place.  If the deck is 3/8" OSB, well, that depression may have come from manufacturing; oops, it got crushed, and they just let it go. 3/8" decking at the edge of a camper where a lot of support does typically not sink.  But, if you have a non-walk-on roof, then they can use a thinner, lighter substrate to glue the membrane, too, and that thin substrate can be more easily damaged.  The lighter substrate non-walk-on roofs save weight and allow more cargo capacity on some brands of camper. 

Now, what do you do with it?   From my camper restoration background, I would do this, and it may be harder for you to do, but I think you can at least do the investigation to have a better place more info to talk with Keystone or the dealer.

I use a moisture meter to scan for wetness. I have used these a lot, and once I understood what the readings were telling me, they have never failed to find something wet that you cannot see from the outside.  I use the General Instruments Model #MMD7NP pinless moisture meter in "wall" mode.  It gives a 0 to 100% reading of relative wetness, not % of moisture, like a pin-type meter can.  It scans up to 3/4" deep behind the sensor for anything wet.  And there is then the learning curve of what the numbers mean. 

Here are the steps I would take. 

Clean the black mold/dirt off the area.  Mold can hold moisture in some cases.  Let the roof dry. 

Using a pinless moisture meter, scan the area where the depression is and around it. Confirm the area is dry or has a level of moisture.  If the system comes up dry, this helps take one course of action. If it comes up wet/damp in the number range, something is going on, which means there is a different course of action.   This meter inspection only takes a few minutes but tells a lot.  Let me know if you want more on the meter; they only cost ~ $45 or so if you want to buy one, the right type for non-destructive testing. 

Next is the red circle area.   This might or might not be a picture anomaly, but the membrane looks slightly puffed up.  A few light taps with the finger may show it is rock solid glued to the decking, or if it is loose, it is not glued down tight.   Do not do this test on a hot summer afternoon; do it in the morning when it is cooler.  The membrane can shrink tight when hot and be puffed up when cooler temps.   This adds another piece of info to go with the moisture meter test on what may be happening or happened.   I'll explain when we know if this is puffed up and wet, dry and puffed up, or dry and tight. What can be a course of action? Fix it or let it go? 

If we can understand there is no water damage, that helps as it creates the start of, this is not a bad thing to live with.  If it is wet, it is time to create a get-well plan.  More on this when the inspection is over,

Next is the red arrow I put on there. If you want to keep this camper for a long time, I highly recommend that the joint between the gutter rail and the roof membrane be cleaned, let dry, and then sealed with a non-sag/non-leveling lap sealant compatible with your TPO roof. Dicor and Alfa Systems make these products.  It will only take approx. 1 tube of caulk to do both sides.  Less than $10 to $20 for the caulk and some time can save you a lot of heartache in the future.  Some RV manufacturers leave that joint un-caulked.  All I can say is it's a cost-cutting measure.   That joint has been a source of water intrusion as the camper ages.  You may make it through the warranty period, but not if you want to keep the camper for many years.  I have seen it and had to repair the camper due to its absence.   Attempting to get Keystone or another RV manufacturer to agree that this needs to be caulked will not get you very far.  Just take it upon yourself to correct it. 

Oh, and I suggest you store the camper level.  The thought of storing it off-level can sooner or later create issues.   The roof draining level allows for a more even water flow off and down the siding than allowing water  to be less in one direction but flood another area.  Yes, the roof should not leak in any situation, but when you flood one area more, the odds are higher against you that a roof seam or siding joint, where any opening is, will, in time, leak.  Siding penetration leaks can be as bad if not worse than roof joint leaks. 

Hope this helps,

John

Hi JK1,

I may be able to help. I have restored many water-roof-damaged campers and can pass along some of what I have  seen and found when doing roof repairs.

A few things, you called your roof to be a rubber roof.  Sadly, the RV industry stopped using actual EPDM rubber a number of years ago.   TPO and PVC membranes are now very common for travel trailers. Both  are a plastic formulation, no rubber at all.  This link to the Coleman site states the Lantern model uses a TPO membrane on a 3/8" decked full walk on arched roof. https://www.dutchmen.com/product/coleman-lantern#constructionOption   If you have something other then the what I found, please tell us what it is you have.  

The pooling or ponding as many roofers call it, can be a long term problem depending where the ponding is occurring and if it constantly ponds in the same spot.    Repetitive ponding happens when the decking has sagged and there is a low spot when the camper is setup level or even nose up or down sometimes.  Left over dirt and mold as time goes on will create a discoloration in the ponding area.  The water evaporates and what is left is the mold/dirt etc. concentrated in that area. The actual membrane can withstand the ponding in it's virgin form, however any caulking/roof sealants that are under water during ponding can be a problem over time.

Can you post a few pics of the roof showing the discoloration and where it is located in relation to any roof seams?  It is easier to talk to what you are seeing then just generic answers. 

I hope this helps.

John

Water pooling on an RV roof would concern me simply for the risk of it finding it's way into one of the many penetrations. RV roofs should have a pitch/dome to keep this from happening. I would push the manufacturer harder. My only question to the OP is, is your RV level?

This is caused by a low spot in the roof or membrane. Water is pooling there, when it dries/ evaporates it leaves the brown spot behind. The minerals left behind can’t be good for the membrane and may well shorten its life. Definitely be bad if pooled water is allowed to freeze. 
It’s a shame that Keystone is not taking care of this issue.