Roof vent(condensation issue)

Hi everyone,
I recently bought a Peugeot Boxer(L2H2).
For now I’m going to leave most of it as it is.
Only I have serious roof condensation issues.
The previous owner had a water tank in the back for his mobile carwash.
That’s probably the cause of all the excess moist in the back…

I was wondering if a simple roof vent could help with this and where I’d best place it?
Also if I should fit an extra vent maybe to make circulation better?
This is a cheap solution that would probably be upgraded in the future.
Therefore I thought about placing it on the roof where there’s place for a window.
That way I can cut it out later when adding a bigger roof vent/window combination…


If there’s water in the back I don’t think just an exhaust vent will do unless you have unlimited time to wait.

Take the van somewhere, where it can be doors open for a few days and have some electric heaters run warm air thru it. Examine where the water is stored, is there some insulation or underfloor cushion that could have been soaked.

It not just the condensation but in the worst case there will be mold as a byproduct. No point building anything in that chassis, until you have sorted that problem.

All of the condensation is on the roof, right now nothing is insulated.
I my boss allows it I could park my van inside the workshop.
The shop is heated, but it’s not exactly hot in there, there’s usually a couple garage doors that are open.

I still think a small vent could be of use to allow fresh air into the back.
The only thing I don’t know is the best position for those.
Maybe the one I showed above on the roof and then one on a lower position?

Are you saying that the van is now an empty shell - all metal? The moisture has to be coming from somewhere, and you have to find where it’s coming from.

If it’s a simple issue of water from the humid air condensing on the cold metal surface, you’ll have to install insulation in addition to installing vents.

Exhaust vents are typically installed in the roof, or at least up high in the side. You also have to provide a way for fresh air to come in. In my van I installed the roof vents toward the back, and installed an air intake in the floor toward the front. There has to be a way for fresh air to come in. Can be an open window or open vents at the opposite end of the van from the exhaust vents. Exhaust vents toward the top and intake vents as low as possible, opposite end of the van.

In the winter, my heater (solid fuel heater) draws the air in through the floor vent, uses that air to burn the fuel, and exhausts through the chimney (flue). The exhaust vents stay closed to prevent drafts. This type of heater dries the air inside the van because all combustion gases are exhausted through the flue.

In the summer I leave the rooftop vents open, most of the time not powered on, and the air enters the floor vent and goes out the roof vents. This is due to the natural tendency of warm air to rise and escape through the roof vents. As long as there’s a way for outside air to come in (in my case the floor vent), outside air constantly flows through the van keeping the inside about the same temperature as the outside air. On hot days when the sun is heating the metal of the van and coming through the windows via greenhouse effect, I accelerate this flow by turning the fans on.

I am thinking about insulation, but I have to plan everything else first…
Also, I am still using the van as a utility vehicle so it won’t be a full camper build…
There used to be a water tank in the van and there’s a few holes in the floor were it was mounted.
But probably it’s just the humid air condensing like you said…

My idea was to have the simple cheap fan on the roof in the front and the inlet grate at the back(low).
This way air can circulate through the van…
Also that way I can remove it later when placing roof windows…

Okay. If it’s moisture in the air causing the condensation, then you have to dry the air while heating it. Warm air can hold a lot more water vapor than cold air, and this is the reason that you have to remove that water vapor from the air. That moisture, caused by your breathing, in the relatively warm air has to go somewhere, and that somewhere is the inside surface of the cold van body.

Use a heater that does not emit water vapor. It has to have an intake and exhaust, and the exhaust has to be vented outside. An electric heater inside the van will do this because it doesn’t burn hydrocarbons - only emits heat, but is impractical on the road unless you’re always plugged into shore power or a gas/diesel generator. That leaves heaters that run on some kind of fossil fuel or wood that have an exhaust pipe to the outside. If it doesn’t exhaust to the outside it won’t keep the air dry enough to prevent condensation.

I’m not sure if i’ll invest in a heating system…
At least not now, I’ll probably only use the van as a camper a few times a year…
When I want to start travelling more I’ll know better what I need I and what I don’t

would you consider making a hole or two behind the seats? Add couple fans (say 140mm computer fans, quiet ones) to blow warm air from the cabin to the rear while you are driving.


If you have a wall/divider between the front & back, you’re no getting enough air circulation in the back. If it has a door in it, try leaving the door open. Get some rain guards for your front windows and leave them cracked open. If it’s a solid wall, remove it or drill a bunch of holes in it, or cut portions of it out.

My portable kerosene heater dries my van out quickly and efficiently, with no holes in the van required, only ventilation.


"Beat Murphy's Law with a KISS! (Keep It Stupidly Simple)" ~ Van_Dweller

I have a closed bulkhead so there’s no connection now.
Would a simple pair of closable vents between the cabin and the back help?
Then when I install the power supply later I can change them for powered ones…
And does it matter if I place these high or low?
Probably can’t hurt to put the roof fan in as well or would you leave it out?


I’m generally opposed to adding any exterior holes in my rigs, especially in the roof.

Vents in the bulkhead might help, both high & low. I would probably add a door in the bulkhead for easy access between the cab and cabin. Mine doesn’t have a bulkhead, and one of my favorite features is being able to go between the front & back without needing to go outside, especially in foul weather.


"Beat Murphy's Law with a KISS! (Keep It Stupidly Simple)" ~ Van_Dweller

I have a three-seater so a door isn’t really an option…
Closable vents in the bulkhead seem the best option(high and low) for now.
But I will add the roof fan and maybe an extra vent.
Otherwise I’ll just blow hot air in the back and the moist won’t be able to escape from there…