Mold on dinette frame under cushions

[PNWtruckCamper]

We recently purchased a new-to-us 2020 Adventurer 89RB, used all of 6 times by the original owner. While looking in all the nooks and crannies to get to know our new truck camper, we discovered surface mold on the wooden seat base under the cushion of the left-hand dinette, along the outside wall and a little into the corner by the fridge. Unscrewing the panel uncovered mold along the top and bottom of the wood frame structure that the wooden seat base sits on, in the same areas (along the outside wall and onto the fridge wall). The cavity underneath that dinette seat holds the hot water heater and a duct from the fridge. Close inspection shows no watermarks on the window or wall above that area, nor signs of drips or pooling underneath or around the water heater. 

Could it be that the water heater itself is a source of condensation in that area? 

Has anyone else had mold in that area and know what caused it? 

The goal is to address whatever the source of it is and prevent it from recurring in the future...

[joerg68]

What do the tips of the screws look like? Less rust, more rust, or about the same as the area near the head? If there is less rust towards the tip, that may indicate that the wall itself is dry and the source of the moisture is somewhere in the camper interior.

Of course that only works if the screws are threaded into wood. But I believe there is still a lot of structural wood in the newer Adventurer campers.

[joerg68]

Suggestion, if you have not been able to localize a leak or additional damage:

Clean the affected areas. Remove mold as good as you can. Let it dry, then treat with an anti-mold agent.

Replace rusted screws with identical new ones.  Personally, I do not use stainless - the rusted screws can be a good indicator for moisture where it is not supposed to be, like in your case.

Use the camper and monitor for re-occurrence.

[PNWtruckCamper]

Great question! Less rust further in/at the tip. 

[Photomike]

When I look at your photos, it helps to narrow down the possible issues. Based on what I see, it looks like picture number one reveals what was under the seat cushions, and picture number two shows mold on both sides of your hot water tank enclosure. BUT it also seems like there's mold higher up.

If that mold is indeed higher and your hot water tank was sealed in with the plywood AND cushions, I suspect water came from above. Is there any way to use a camera or cell phone to see what's behind that wall board?

If the mold was just under the seat, it could suggest a leak in one of the lines to the hot water tank, spraying water around. But if there's no mold on the floor under the seat or signs of water, like disturbed dust with a trail, and the mold is higher up, it likely came from above. This would prompt me to inspect the roof for any damage or missing parts, like a cap for a fridge vent.

[StirCrazy]

is the area vented?  warm humid and no ventalation is a recipie for mold.  if you can find a way to add a couple vents to the area so there will be some air movment that should reduce the issue.  

[PNWtruckCamper]

Not really at all, no. And the previous owner stored the unit was stored with all doors shut, so the one hole in the under-bench storage cubby that gives access to the hot water heater was closed in quite tightly.

We plan to cut holes in the top panel to better ventilate going forward.

[Photomike]

In a new unit, used only six times, there has to be a source of moisture/water. The water heater is a sealed unit.  There should be zero moisture being introduced to that are to cause the need for ventilation.  If there is moisture in there it is better to eliminate the cause then to vent.

[nickthehunter]

In an RV in the PNW used only 6 times in 3 years the source of the moisture is the high humidity typical of the PNW. The unit likely suffers from the lack of being opened up regularly to dry out - hence, it molds.

[Grit_dog]

I’d say this is 99% likely the case. 
Ifnit sat outside uncovered for even 1 winter on the wet side of the mtns I could easily see this happening. 
I have an enclosed trailer that sits outdoors 24/7/365 uncovered and from about Oct to April I keep a box fan running in it continuously at a minimum as well as a milk house heater for a few days after we go snowmobiling until the sleds and floor all dry out 100%. 
If I don’t, the condensation is immediate and mold like this begins popping up quickly. 
Just bleach wipe everything down that’s moldy, and keep ventilation in it during the wet season. 

[PNWtruckCamper]

 
(Shot while screw removal in progress)

[MORSNOW]

Looks to be moisture from above to me.  The water heater is a sealed and insulated unit that looks dry and mold free on its bottom area, that we can see anyway.  Water can and will enter at any exterior penetration like marker lights, vents, windows, etc. and also can travel along framing members until able to run downwards.  I'd start by cleaning and resealing every exterior penetration.  

[StirCrazy]

the only issue I see with "from above" is the mold stops at the hight of the seat cushions.  it makes me think there was some sort of high humidity/storage type thing going on..  or direct moisture under the seat.  but ya it could have been leaking down the inside of the wall and just coming out at the bottom. 

[PNWtruckCamper]

What's noteworthy is that there is no mold in the joint between the frame and wall. Only surface mold in the form of black spots at the top and bottom of the panel that's the dinette seat and the same surface black spots on the top of the frame. The most severe mold (extensive, fuzzy growth) is on the "inside" lip of the frame and on the underside. 

[PNWtruckCamper]

photos to help illustrate: